1 2 Previous Next 45 Replies Latest reply on Jul 9, 2009 7:24 AM by Dag Norum

    Hilights Clipping Problem with Premiere CS3 Media Encoder

    MarkWeiss Level 1

      I've just discovered a pretty serious problem with the way Premiere CS3 processes video to the Media Encoder.

       

      Many of you are familiar with the term "super whites", the ability of modern cameras to capture and record levels above 100 IRE. With HDV and newer technology, recording to 109 IRE is quite common.

       

      I was aware for some time that importing this footage into Premiere results in a hard truncation of whites above 100 IRE. However, I discovered last month that the Fast Color Corrector has a Output Levels adjustment that can rescale all the levels to fit down in the 0-100 IRE range. I verified this using the scopes in Premiere and by observing recovered details in my footage. I was even able to export frames to TIFF files and show the recovered highlights in the exported TIFFs. The difference is substantial and not subtle--it's the difference between a sky completely blown to white and one where you can see the sky is blue with clouds in it.

       

      Last night, I discovered that the Unsharp Mask filter doesn't handle footage above 100 IRE, either. Even if I use Levels to set 0-235 RGB range, somehow, Unsharp Mask is processing the un-level-adjusted signal, regardless of stacking order of the filters.

       

      I rendered two Blu-ray discs, one with Unsharp and the other without. To my astonishment, BOTH discs lacked any detail in the highlights--the whites were clipped at 100 IRE!

       

      Now I turned attention to the Media Encoder. Pausing on a frame where I can see the difference between 100 IRE and 109 IRE and shades in between, I fire up the Media Encoder and note that even in ME's previews screens, the whites are already clipped. There is more highlight detail in the program monitor, whereas it's all gone in the Media Encoder's display.

       

      It is obvious that highlight information, even scaled back to 0-235, is being treated as if it were 0-255 and clipped at 235 before passing to the encoder. This is a real disappointment, because there is another half f-stop of detail up there that I was trying to pull into the useable range of 100 IRE for the Blu-ray disc. Since it is very difficult to shoot footage and limit the peak whites in-camera to no more than 100 IRE, nearly all of us are losing valuable picture information.

       

      Even if you can recover the highlights on the timeline through a Levels filter, it gets thrown away again on the way to the Media Encoder. Short of exporting a few hundred thousand frames as .TGA files and then loading those back in and rendering out to whatever motion CODEC, I am at a loss as to how to get Premiere to leave the whites intact.

       

      I haven't seen this issue discussed in any detail here. Has anyone found a way around it, besides reshooting all your footage of one-time events to sub 100 IRE levels?

        • 1. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
          MarkWeiss Level 1

          There is a whole discussion about this on DVinfo.net:

           

          http://www.dvinfo.net/conf/attend-world-premiere/122522-restore-clipped-highlight-detail-p remiere-pro-cs3-superwhites-2.html

           

           

          These folks discovered the same problem with Media Encoder:

           

          "Exporting via Media Encoder always results in the original superwhites being clipped, even if the superwhites were brought down to legal values with the "good" filters. It appears that Media Encoder first clips superwhites and only then applies the filters. "

           

           

           

           

          Presently, I am exporting a segment to an uncompressed AVI, thanking myself that I just installed a 2-terabyte RAID array in the editing workstation, because it's going to fill most of that space at 1920x1080 per frame. Short tests show that exporting as movie (AVI) doesn't clip the highlights that were corrected with the Fast Color Corrector and imported short AVI segments could be re encoded to Media Encoder without losing highlights, because the exported AVI had the levels adjusted to video-legal levels.

           

          Now my only concern is this double rendering may degrade my footage by adding an extra rendering step to the process.

          • 2. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
            MarkWeiss Level 1

            I just finished rendering out the h.264 file from the uncompressed AVI that I exported. The hilights look okay, but the whole file looks like it was upscaled from DV, not a true HD file. I couldn't notice it in Premiere's preview window, as that only displays 1/2 of the 1080 lines, but upon careful investigation, I discovered that the export movie mode defaults to FIELD RENDERING (ie. INTERLACED). Ackkk! That was 3 hours down the drain.

             

            Now I'm starting the process all over again, this time with the export keyframing menu set to Progressive. Then 2.5 hours encoding to h.264 and then we replace file in Encore, render and burn a Blu-ray.... seems like that will be six hours away, if nothing else goes wrong!

            • 3. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
              Dan Isaacs Level 2

              Interesting. That's a messed-up problem. I have not verified it myself, but it seems to indicate that the clips are being converted from YUV to RGB prior to appying filters when outputting via Adobe Media Encoder. CS3 is kind of flaky in its handling of different color systems, so this really comes as no surprise to me.

               

              I always use intermediary AVI files for encoding anyway (never, in practice, do I directly output from AME). In truth, depending on the complexity of your project, outputting a intermediary can greatly speed up encoding; particularly with HD material and much more so on 2-pass encodes.

               

              One suggestion, however: consider using a lossless codec, such as Lagarith, instead of uncompressed. Lagarith has an option for multithreading, which can greatly improve rendering speed from Premeire (compared to uncompressed) on multicore / multiprocessor machines.

               

              Usually, I output via DebugMode FrameServer and then use Virtual Dub to compress the AVI, and/or some other encoder for MPEG, etc.

              • 4. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                Jeff Bellune Adobe Community Professional

                Try this (I have not tested it here):

                 

                Set the sequence to use I-frame only MPEG files as the preview file format.  Render a portion of the sequence that contains the corrected super whites.  After rendering, play back the rendered portion and verify that the corrected super whites appear as you expect in the Program Monitor.

                 

                If so, render the entire sequence and set the AME to use the rendered preview files for export.

                 

                -Jeff

                • 5. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                  Dag Norum Level 2
                  set the AME to use the rendered preview files for export

                   

                  Jeff, for once I shall be nice

                   

                  I wonder if you maybe will think a little about when the "use preview files" was introduced. Not to make any fun of it at all, but this is the CS3 forum....

                   

                  Dag

                   

                   

                  EDIT: Nice "work around / get the job done" thinking though!

                  • 6. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                    Dag Norum Level 2

                    Mark,

                     

                    Thanks for the finding!

                     

                    One to keep in mind.

                     

                    Dag

                    • 7. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                      Jeff Bellune Adobe Community Professional

                      Dag Norum wrote:

                       

                      set the AME to use the rendered preview files for export

                       

                      Jeff, for once I shall be nice

                       

                      I wonder if you maybe will think a little about when the "use preview files" was introduced. Not to make any fun of it at all, but this is the CS3 forum....

                       

                      Dag


                      Not necessary to be nice.  When I make stupid statements I deserve to be treated like an idiot, same as everyone else!

                       

                       

                       

                      -Jeff

                       

                      PS - Just to clarify for everyone, "use preview files" was introduced in CS4, not CS3.

                      • 8. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                        Dan Isaacs Level 2

                        On that note, Jeff: Would you care to verify whether this problem has been fixed in CS4 (with or without the "use preview files" option)?

                        • 9. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                          Jim_Simon Level 8

                          Not necessary to be nice.  When I make stupid statements I deserve to be treated like an idiot, same as everyone else!

                           

                          Does that mean I can finally say to those deserving noobs;

                           

                          "Dude, you're an idiot.  You have no idea what you're doing, and no business using this software.  So just get the [bleep] out of here!"

                          • 10. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                            Jeff Bellune Adobe Community Professional

                            JSS1138 wrote:

                             

                            Not necessary to be nice.  When I make stupid statements I deserve to be treated like an idiot, same as everyone else!

                             

                            Does that mean I can finally say to those deserving noobs;

                             

                            "Dude, you're an idiot.  You have no idea what you're doing, and no business using this software.  So just get the [bleep] out of here!"

                            No.  What that means is that you can abuse those who you know for sure should know better.  FYI, that's a very short list of members.

                             

                            "Noobs", by definition, do not know any better and you must still treat them with proper dignity and respect.

                             

                            Nice try, Jim. 

                             

                            -Jeff

                            • 11. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                              Jim_Simon Level 8

                              On a more serious note, I found another disturbing aspect to this issue.  Magic Bullet Looks.

                               

                              Here's the original, unaltered levels.  (I really wish my camera would shoot proper video, instead of out of range video.)

                              Original.png  Original_v.png

                               

                              Here's the Fast Color Corrected clip.  As you can see, my blue skies came back.

                               

                              FCC.png  FCC_v.png

                               

                              Now here's the same FCC clip with a blank MB Looks effect applied.  Notice the crushed skies?  They went from a range of 70-100 down to 80-90 and lost most of the color.

                               

                              Looks1.png  Looks1_v.png

                               

                              No matter what I tried, I could not get Looks applied to an FCC clip within Premiere.  Seems Looks always goes back to the original and clips the levels.  The only thing that worked was exporting an FCC clip, adding that to the project and applying Looks to that.  (See Below.)

                               

                              Looks2.png Looks2_v.png

                               

                              This is a serious problem.  Though I'm not sure who to be the more angry with, Magic Bullet for the way their plug-in works, or Panasonic for shooting out of spec video in the first place.

                              • 12. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                Jim_Simon Level 8
                                you can abuse those who you know for sure should know better.

                                 

                                Ah, but there's the rub.  Anyone using software at this level should know better before they use it.

                                • 13. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                  Jeff Bellune Adobe Community Professional

                                  Dan Isaacs wrote:

                                   

                                  On that note, Jeff: Would you care to verify whether this problem has been fixed in CS4 (with or without the "use preview files" option)?

                                  You mean I gotta go find a superwhite clip that's usable for testing, and then do some more tests?  Ugh!  Don't hold your breath...

                                   

                                  -Jeff

                                  • 14. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                    Jim_Simon Level 8

                                    I'll post the sample I used above so anyone can download.

                                    • 15. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                      Jeff Bellune Adobe Community Professional

                                      Thanks, Jim.  That'll help a lot.

                                      • 16. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                        Dan Isaacs Level 2
                                        Though I'm not sure who to be the more angry with, Magic Bullet for the way their plug-in works, or Panasonic for shooting out of spec video in the first place.


                                        Jim – there is nothing wrong with the way your camera shoots video. The DV luma spec is 16-255. The extra range (235-255) is there by design to give a little bit of latitude for adjustment (and other, more techy reasons like Nyquist limit, etc.). This is analogous to pro audio, which has long been recorded in 48kHz despite the fact that CDs are only 44.1kHz.

                                        • 18. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                          Jim_Simon Level 8

                                          there is nothing wrong with the way your camera shoots video.

                                           

                                          I guess the more important issue is that there is something wrong with the way it looks on the final TV when edited in Premiere.  Where the error lies is of somewhat lesser concern than getting it corrected, not on a clip by clip basis, but easily corrected across an entire program.  Having all cameras shoot strictly within the Rec. 601 range of 16-235 seems the easiest fix.  (At least from a user standpoint.  Actually implementing that fix would be somewhat of a challenge, which is why I hope this thread yields another.)

                                          • 19. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                            MarkWeiss Level 1

                                            Dan,

                                            I tried Lagarith, but it only produced black frames when rendering to it, plus the presence of Lagarith on the system disabled Premiere's ability to export movie in ANY uncompressed format. I uninstalled it and regained those abilities.

                                            I do have HuffYUV, but I've had some crashes in the past, using it.

                                            Other option is Apple Photo JPEG at quality level of 100, which is said to be lossless 4:4:4.

                                            For now, the uncompressed 10-bit YUY is working okay.

                                            • 20. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                              MarkWeiss Level 1

                                              Jeff,

                                               

                                              The render codec is greyed out in that menu, but IS set to I-frame only MPEG.

                                               

                                              When I render ANY preview on the timeline, my video gets replaced with "Media Pending", so I can't render any previews.

                                              • 21. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                                MarkWeiss Level 1

                                                Jim,

                                                 

                                                There is nothing wrong with your camera. In fact, what you've got hidden up there is almost an extra f-stop of dynamic range. That means, if we can use it, we can push the noise floor down a bit. Cleaner footage is a good thing, yes?

                                                 

                                                FWIW, XDCam has a CINE2 gamma that is hard-limited at 100 IRE for just this sort of thing. Only problem is that the pictures are so low-key that I am not convinced I'd be taking advantage of the camera's full dynamic range.

                                                 

                                                An example from a project I'm working on:

                                                 

                                                Here is the original image, as interpreted by Adobe Premiere with it's arbitrary clipping at 100 IRE.
                                                Frame (clipped hilights).jpg

                                                 

                                                Here is that same frame, with RGB Curves applied so as to bring all portions of the image to within 100 IRE. There is substantial detail in the clouds that is whited out in the uncompensated image. Almost an f-stop of additional detail found above Premiere's normal working limit!
                                                Frame (recovered hilights).jpg

                                                 

                                                Pretty dramatic, eh?

                                                I wish Adobe would handle the full dynamic range through it's Media Encoder. For now, I'm using terabytes of disc for all those uncompressed HD clips.

                                                • 22. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                                  Jeff Bellune Adobe Community Professional

                                                  Here's a brief summary of what I discovered:

                                                   

                                                  1. The Unsharp Mask effect problem is fixed in CS4.
                                                  2. The AME source and output preview images are not accurate in CS4.  They do not display the results of the FCC Output level change.
                                                  3. The actual output from the AME in CS4 is perfect.  Tested for both H.264 and MPEG2 DVD.
                                                  4. I-frame MPEG preview files used for an SD sequence in CS4 have a unique set of issues on my system.  That's a topic for another day.

                                                   

                                                  Jim's clip in the Pr CS4 timeline after the FCC effect applied:

                                                   

                                                  FCC-Timeline.jpg

                                                   

                                                  The AME preview of that same timeline:

                                                   

                                                  FCC-AME.jpg

                                                   

                                                  The output of the AME after it has been exported, imported into Pr CS4, and placed on the timeline:

                                                   

                                                  ExportedAME-Timeline.jpg

                                                  @Mark:

                                                   

                                                  Could the same be true for CS3?  Is it only the preview in the AME that is smurfed?  Is the actual output OK?

                                                   

                                                  -Jeff

                                                  • 23. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                                    MarkWeiss Level 1

                                                    No, it's definately not just preview (in CS3) that exhibits the clipped whites, it's the rendered h.264 footage as well. I have two different Blu-ray discs, one in which I rendered direct from the timeline with the FCC filter, and the latest one, where I rendered to movie (AVI) uncompressed with the FCC filter and then imported that into the project, applied my unsharp mask and rendered to AME's h.264. The latter BD-R disc has highlight detail that is clearly missing on the former BD-R disc.

                                                     

                                                    If this is fixed in CS4, that's nice, but our 3.5GHz quad core PCs with 4GB RAM and nVidia Quadro 4600 are not up to running it. It's like running CS3 on a '486, if you can imagine how poorly it runs. We rolled back to CS3 in February after a two month concerted effort to make it run smoothly.

                                                    • 24. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                                      Jim_Simon Level 8
                                                      what you've got hidden up there is almost an extra f-stop of dynamic range. That means, if we can use it, we can push the noise floor down a bit. Cleaner footage is a good thing, yes?

                                                       

                                                      If done easily, yes.  As it is, it looks like such adjustments will need to be done on a clip by clip basis.  That's just too much damn work.  I'd rather the camera added that extra lattitide within the appropriate 0 to 100 IRE range.

                                                      • 25. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                                        Dan Isaacs Level 2
                                                        I'd rather the camera added that extra lattitide within the appropriate 0 to 100 IRE range.

                                                         

                                                        That's a lot like saying you want 10 gallons of water in an 9-gallon jug.

                                                         

                                                        As it is, it looks like such adjustments will need to be done on a clip by clip basis.

                                                         

                                                        Or, you can do it the "Dan" way in AviSynth. I wrote a script function called SoftLimiter: It applies photoshop-style curves on the Y + U + V channels to bring the maximums within legal range… using a sort-of "soft-knee" approach to reducing extreme highlights and/or oversaturated areas.

                                                         

                                                        It causes a tiny bit of posterization in the highlights, just like all 8-bit per channel color adjustments do… but it is hardly noticeable on a computer screen and even less on TVs.

                                                         

                                                        SoftLimiter for AviSynth 2.5

                                                         

                                                        Create a folder C:\SoftLimiterCurves\ and place the .amp curves files in that folder.

                                                        Place the other files in your AviSynth 2.5 / plugins folder.

                                                         

                                                        The example below assumes DV avi files and requires a DV codec (such as Cecocida DV, MainConcept, Canopus) that can read / write in YUV formats.

                                                         

                                                        1. Create a script like this:

                                                          AviSource("dv.avi", pixel_type="YUY2")
                                                          SoftLimiter()


                                                        2. Open the script in VirtualDub, use Video / Fast Recompress, Select Cedocida DV codec. File / Save as .avi

                                                         

                                                         

                                                         

                                                        Before:

                                                        softlimiter_before.png

                                                         

                                                        After:

                                                        softlimiter_after.png

                                                         

                                                        And, Jim… you can place your dv2film() command at the end of this script if that's what you're trying to accomplish.

                                                        • 26. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                                          Jim_Simon Level 8

                                                          Or, you can do it the "Dan" way in AviSynth.

                                                           

                                                          I like that idea, but I notice the blue sky isn't quite as blue in the "Dan" clip as it is in the FCC corrected versions.

                                                           

                                                          When working on the clips in Premiere, I did notice that to get the chroma levels into the proper range (and hence all available detail), I had to adjust the FCC output down to 210 for this particular clip, considerably lower than the norm of 235.  This amount of reduction also seemed to vary by clip.  Some clips worked fine using a 235 output, but many needed a lower output.  One clip I had to reduce down below 200 to get a proper 100IRE limit.  What the [bleep] is going on here!?

                                                          • 27. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                                            Dan Isaacs Level 2
                                                            I like that idea, but I notice the blue sky isn't quite as blue in the "Dan" clip as it is in the FCC corrected versions.

                                                             

                                                            That's because the Dan method is correct (I had to say that). With SoftLimiter, only the extreme values are touched: the rest of the image is intact (see the histograms at the bottom of the frames).

                                                             

                                                            Instead of simply scaling 0-255 -> 0-235 (like FCC), my function only scales ~210-255 -> ~210-235. The only purpose is to bring the extremities into range. You can then use another filter (like Looks or whatever) to make your skies as blue as you want.

                                                             

                                                            Some clips worked fine using a 235 output, but many needed a lower output.  One clip I had to reduce down below 200 to get a proper 100IRE limit.  What the [bleep] is going on here!?

                                                             

                                                            Exactly. Thus, you'll be inadvertently adjusting the midtones as well instead of simply compressing the highlights.

                                                             

                                                            You don't need to worry about "proper IRE limits" in Premiere. If you export via AME to DVD, your video will be converted to RGB using Rec.601 coefficients – and then back to YUV again, which will effectively clip all out-of-range values.

                                                             

                                                            Your only concern, really, when making color adjustments in Premiere is that it looks, artistically, the way you want it to look. Contrarily, there is nothing "artistic" about my SoftLimiter function. It is utilitarian all the way. It tweaks the levels just enough so that the upper range is unaffected during YUV->RGB conversion.

                                                             

                                                            I trust the scopes in Premeire as much as I trust the realiability of its filters, which is as much as I trust its handling of different color systems, which is to say: I don't trust it at all.

                                                             

                                                            If you are outputting using HC Encoder, you'll necessarily need an AviSYnth script to feed your video to HC. So, it's easy enough to ensure legal values there:

                                                             

                                                            AviSource("myvideo.avi")

                                                            ConvertToYV12(interlaced=true)

                                                            Limiter(16, 235, 16, 240)

                                                            • 28. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                                              Jim_Simon Level 8

                                                              That's because the Dan method is correct

                                                               

                                                              Hmm.  Being the one who shot the video, I have to say the FCC clips are a more accurate representation of the actual day.

                                                               

                                                              Thus, you'll be inadvertently adjusting the midtones as well instead of simply compressing the highlights.

                                                               

                                                              That's actually what I want, for the whole image to be properly scaled back into the correct 0 to 100 IRE range.  It's sort of like adjusting a finished music/effects/dialogue mix that just happens to be clipping.  I'd want to bring all the levels down to keep the same "mix", rather than just adjusting the sounds that are too loud.

                                                               

                                                              If you export via AME to DVD

                                                               

                                                              I don't, instead preferring the frameserved HC Encoder method.  It gives better results.  I'd also have to find a way to do this during the dv2Film conversion, as Looks seems to always affect the original clip with hard clipping.

                                                              • 29. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                                                Dan Isaacs Level 2
                                                                I have to say the FCC clips are a more accurate representation of the actual day

                                                                 

                                                                That has nothing to do with it. This would simply mean that the shot was overexposed… but it is not: It's just that the "brights" exceeded the dynamic range of video standards.

                                                                 

                                                                It's sort of like adjusting a finished music/effects/dialogue mix that just happens to be clipping.  I'd want to bring all the levels down to keep the same "mix", rather than just adjusting the sounds that are too loud.

                                                                 

                                                                Umm… this is exactly why compressors and limiters are used in audio mastering. But now we're getting entirely off-topic.

                                                                 

                                                                I'd also have to find a way to do this during the dv2Film conversion,
                                                                as Looks seems to always affect the original clip with hard clipping.

                                                                 

                                                                AviSource("dv.avi")

                                                                Levels(0, 1.0, 255, 0, 235, coring=false)

                                                                dv2film()

                                                                 

                                                                … which will scale the 0-255 -> 0-235, but it will reduce the overall brightness of the image. Furthermore, by virtue of the fact that nearly all frequencies are being adjusted, you run greater risk of banding if you apply color correction later on.

                                                                 

                                                                This is why I wrote SoftLimiter()… to increase the apparent dynamic range of the image when it is converted to RGB as non-destructively as possible given the constraints of 8-bit/channel video - and to better facilitate secondary RGB color correction.

                                                                • 30. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                                                  MarkWeiss Level 1

                                                                  If only the highlights get compressed, that will introduce nonlinearities into the picture. I prefer to scale the whole image to the new boundaries. It also deepens the color and makes a more theatrical look to the clip.

                                                                   

                                                                  I'd say it is prudent to beware of the highlights in Premiere, since Premiere's export to AME is going to clip the heck out of the highlights. And that looks bad to my eyes, although it doesn't seem to look bad to major Hollywood directors who clip the heck out of their highlights, crush their blacks and overall just make the picture too contrasty. Me, I like the look of a hi-fi picture. What I've tweaked and put onto Blu-ray looks amazing--like you were looking at the scene with 20/20 vision and hyper-vivid colors.

                                                                  • 31. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                                                    Dan Isaacs Level 2
                                                                    that will introduce nonlinearities into the picture

                                                                    So what? So will any curve or gamma adjustment. Are you saying that one should never apply curves for fear of destroying such linearity? Does the same logic apply to digital photography? It seems to me that is more or less impossible to do nice color correction of photos without curves. And why would it be different for video?

                                                                     

                                                                    Furthermore, "linear" adjustment is only linear in terms of numbers and has little relation to how we perceive color or brightness in real life.

                                                                     

                                                                    Of course, you are free to darken your clip if you like the "look" of that: But this does not apply when you have a clip that is already properly exposed and you simply want to recover a little lost detail from the highlights.

                                                                    • 32. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                                                      MarkWeiss Level 1

                                                                      The issue I see with applying a curve to a limited region of an image's luminance is that it deviates from the way the rest of the tone range is handled.

                                                                      The highlights character will be altered and look odd if only that range is adjusted. Spreading adjustment over the whole range provides a smooth transition over the whole tone range and won't make the brights look odd. The slight darkening in the mid tones can be lifted a bit with the middle slider in the Levels adjustment, and done over a broad range to reduce abrubt changes in tone.

                                                                      • 33. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                                                        Dan Isaacs Level 2
                                                                        The issue I see with applying a curve to a limited region of an image's luminance is that it deviates from the way the rest of the tone range is handled.

                                                                         

                                                                        Again, that's what curves do.

                                                                         

                                                                        The slight darkening in the mid tones can be lifted a bit with the middle slider in the Levels adjustment


                                                                        That's gamma. It is non-linear. It is a curve also. If you scale the highlights and then tweak the middle, you are basically doing the same thing that I suggest but will less precision and you're unecessarily scaling the whole thing down just to scale it back up again. And, when working at only 8-bits/channel, you causing some damage by these repeated adjustments.

                                                                         

                                                                        Also note that, when working in RGB, adjusting the gamma also affects the overall saturation of the clip.

                                                                         

                                                                        Spreading adjustment over the whole range provides a smooth transition over the whole tone range and won't make the brights look odd

                                                                         

                                                                        To date, I have never really witnessed odd-looking brights as a result of process.

                                                                         

                                                                        and done over a broad range to reduce abrubt changes in tone

                                                                         

                                                                        Not abrupt at all. This is the curve that I use on the luminance channel:

                                                                         

                                                                        curve.png

                                                                        • 34. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                                                          MarkWeiss Level 1

                                                                          That is the same curve I have also tried with the Luma Curve filter, which also works. However, without richening the mid tones, I find that in shots like the aircraft above in this thread, the details on the reflections get muted too much. I like the results with the Levels adjustment better for this reason.

                                                                          • 35. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                                                            Jim_Simon Level 8

                                                                            If only the highlights get compressed, that will introduce nonlinearities into the picture. I prefer to scale the whole image to the new boundaries. It also deepens the color and makes a more theatrical look to the clip.

                                                                             

                                                                            My thinking exactly.

                                                                            • 36. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                                                              Jim_Simon Level 8

                                                                              The highlights character will be altered and look odd if only that range is adjusted. Spreading adjustment over the whole range provides a smooth transition over the whole tone range and won't make the brights look odd.

                                                                               

                                                                              Again, ditto.  The look of the FCC clip is a better representation of reality than the 'Dan' clip.  (Don't mistake that for criticism.  It's just an effort to get the best picture.)

                                                                              • 37. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                                                                Dan Isaacs Level 2
                                                                                The look of the FCC clip is a better representation of reality…

                                                                                 

                                                                                You are clearly missing the point: My method is intended to facilitate better secondary color correction. If you are going to use RGB Curves or some other 3rd party RGB color correction tool or whatever to get the clip to look as you like ("reality" or otherwise), compression of the highlights will make it possible for you to do this without clipping.

                                                                                 

                                                                                There is nothing unrealistic about compressed highlights. This si very much the way our eyes see things; rather, our eyes adjust so quickly when moving for dark subjects to bright ones that compressing the range is the best way to simulate this.

                                                                                 

                                                                                Example: Imagine a filiment inside of a brightly illuminated lightbulb. If you look very closely at the lightbulb, you can see the filiment inside. And, despite the overall brightness, you can see shading and reflections due to the curvature of the lightbulb. It is possible to see all of this detail and, at the same time, to be able to see the area surrounding the lightbulb in "normal" contrast because your eyes adjust quickly – and your brain "composites" the bright/dark images faster than you are able to realize what's going on.

                                                                                 

                                                                                Now, try to photograph what you've seen: It is very hard to preserve the filiment and highlight details on the lightbulb without making the surrounding area appear extremely dark. This is why photographers use things like graduated neutral density filters.

                                                                                 

                                                                                However, without richening the mid tones, I find that in shots like the
                                                                                aircraft above in this thread, the details on the reflections get muted
                                                                                too much.

                                                                                 

                                                                                If you want to preserve more details in the highlights while having richer midtones, my best advice would be to reshoot and underexpose by a half-stop or so (or maybe you can try using a graduated neutral density filter???).

                                                                                • 38. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                                                                  Jim_Simon Level 8
                                                                                  If you are going to use RGB Curves or some other 3rd party RGB color correction tool or whatever to get the clip to look as you like

                                                                                   

                                                                                  That's actually part of the point, to not have to use such things to make the clip look as it did when shot.  Correcting every single clip in a video is just not practical - at least not for the money I'm making.  Maybe in Hollywood...

                                                                                   

                                                                                  This is why I wish the camera would shoot only in-range video.  That makes things very easy and correct.  (And I notice that OnLocation will clip to the proper 100 IRE limit, despite the idea of 255 being legal for DV.)

                                                                                   

                                                                                  maybe you can try using a graduated neutral density filter???

                                                                                   

                                                                                  Now that is good advice for outdoor shots that include sky.

                                                                                  • 39. Re: Hilights Clipping Problem with Premiere CS3 Media Encoder
                                                                                    Dan Isaacs Level 2

                                                                                    OK, Jim. I realize that this argument can go around and around forever…

                                                                                     

                                                                                    That's actually part of the point, to not have to use such things to make the clip look as it did when shot.

                                                                                     

                                                                                    You don't really have to at all… It is only in certain cases.

                                                                                     

                                                                                    My SoftLimiter function is something that can (safely) be applied to all clips… shots that do not contain bright highlights (such as underexposed shots) will not be affected at all. Shots with "normal" highlights will only be minimally affected, and probably with little discernable difference from the original… while shots with lots of bright highlights will get squeezed into range without affecting the overall contrast of the original – and the final result will always be "broadcast-legal".

                                                                                     

                                                                                    So, in a sense, you could say that my method simulates a graduated neutral density filter.

                                                                                     

                                                                                    And I notice that OnLocation will clip to the proper 100 IRE limit

                                                                                     

                                                                                    That's not a good thing. I am assuming this means that OnLocation does not directly transfer the DV stream but, instead, does 4:1:1 -> RGB -> 4:1:1, which may be sacrificing a lot more than just the highlights. But, this is off-topic and pure speculation on my part, as I have never used OnLocation.

                                                                                     

                                                                                    Clipping is the easy part: Performing a perceptually accurate conversion from a larger range to a smaller one is a bit more complicated.

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