31 Replies Latest reply on Oct 16, 2011 10:06 AM by Noel Carboni

    ACR Feature request: RAW Histogram

    sbv242

      Hello,

       

      I'd like to suggest a new feature for Camera Raw plugin: the ability to switch between "standard" and RAW histogram (which covers the full data range present in RAW file).

       

      Thank you.

        • 1. Re: ACR Feature request: RAW Histogram
          ssprengel Adobe Community Professional & MVP

          If you mean a histogram in terms of the 12-bit or 14-bit or whatever-bit binary numbers for each of the sensor’s photosites without any camera profile or working colorspace applied, then it would always be very skewed left and, in my opinion, relatively useless.

           

           

           

          If you are asking for something else then please clarify.

          • 2. Re: ACR Feature request: RAW Histogram
            Noel Carboni Level 7

            There is simply no absolute definition for a "standard" histogram.

             

            If you're referring to what's displayed on the back of a camera, it's just another interpretation of the data, optimized for use while shooting.  If you're talking about some kind of reading of what's in the actual sensor readings, that would actually be too geeky to be useful.

             

            Perhaps it would be helpful if you would list what goal it is you're trying to accomplish.  I'm sure folks will be happy to discuss how to help you reach it.

             

            -Noel

            • 3. Re: ACR Feature request: RAW Histogram
              Level 4

              sbv242 wrote:

               

              …I'd like to suggest a new feature for Camera Raw plugin: the ability to switch between "standard" and RAW histogram (which covers the full data range present in RAW file)…

               

              You need to do quite a bit of reading to begin to understand raw capture.

               

              A raw capture would be a very, very, VERY dark grayscale image containing nothing that the human eye could discern as color.  A "histogram" of that would be of absolutely no value to anyone, including you.

               

              Color is introduced at the time of demosaicing in the raw converter, and that will always be according to what the developer of the conversion program designed to render.

               

              What you see in the LCD in the back of your camera when "chimping" is a representation of the JPEG conversion performed by the camera's own software, not a representation of your raw image.

               

              This would be a good place to start learning:

               

              http://www.amazon.com/Real-World-Camera-Adobe-Photoshop/dp/0321713095/ref=dp_ob_title_bk

               

               

              ____________

              Wo Tai Lao Le

              我太老了

              • 4. Re: ACR Feature request: RAW Histogram
                Vit Novak Level 3

                Well, some programs have raw histogram, like Canon DPP for instance. It is B/W (although it could be in color I suppose) and x axis is logarithmic (range about -9 EV .. +3.5 EV), so it's not skewed left

                 

                Also, there seems to be real tone curve over it in DPP, while ACR doesn't show real tone curve (you can see it only in dng pe)

                • 5. Re: ACR Feature request: RAW Histogram
                  Level 4

                  Vit Novak wrote:

                   

                  Well, some programs have raw histogram, like Canon DPP for instance. It is B/W (although it could be in color I suppose) and x axis is logarithmic (range about -9 EV .. +3.5 EV), so it's not skewed left

                   

                  Sounds about as useful as the Pope's gonads or the guardian angels of the Kennedy family.   It also sounds not very close to the raw capture already.

                  • 6. Re: ACR Feature request: RAW Histogram
                    Vit Novak Level 3

                    Don't know, as I don't use DPP anyway ... but obviously someone in Canon thought it was usefull

                     

                    However, --sometimes-- it would be usefull to know which parts of the photo are actually blown on raw, as ACR doesn't offer this information

                    • 7. Re: ACR Feature request: RAW Histogram
                      Level 4

                      Vit Novak wrote:

                       

                      …--sometimes-- it would be usefull to know which parts of the photo are actually blown on raw, as ACR doesn't offer this information

                       

                      Give me a break… if you tell me Vit Novak can't tell that with the info provided by ACR now, I'll just not believe you. 

                      • 8. Re: ACR Feature request: RAW Histogram
                        Yammer Level 4

                        I wish there was such a thing on my camera, with a logarithmic x-axis of course. Camera manufacturers seem to always give you a processed histogram, which is a bit misleading if you shoot raw, and doesn't make ETTR as easy as it could be. Raw RGB histograms would be great for letting you know how much headroom you have left, although they will probably be less useful with the newer generation of sensors producing less read noise.

                         

                        I'm not sure how useful it would be in ACR, but I often wonder which channels of a bright image are actually blown. The existing indicators only show which channels are blown with the current develop settings. So raw clipping indicators would definitely get my vote.

                        • 9. Re: ACR Feature request: RAW Histogram
                          Vit Novak Level 3

                          Tai Lao wrote:

                           

                          Vit Novak wrote:

                           

                          …--sometimes-- it would be usefull to know which parts of the photo are actually blown on raw, as ACR doesn't offer this information

                           

                          Give me a break… if you tell me Vit Novak can't tell that with the info provided by ACR now, I'll just not believe you. 

                           

                          Well, I suppose I could make a profile to show me that, but I didn't try

                           

                          Highlight clipping warning in ACR seems to be showing areas where at least one of channels reached saturation in selected output color space. So what is shown as clipped isn't necessary clipped in raw. And what isn't shown as clipped can be clipped in raw with some profiles (at least Canon camera profiles)

                           

                          This information can be obtained for instance using dcraw utility, with some switches ...

                          • 10. Re: ACR Feature request: RAW Histogram
                            Noel Carboni Level 7

                            Vit Novak wrote:

                             


                            it would be usefull to know which parts of the photo are actually blown on raw, as ACR doesn't offer this information

                             

                            Sure it does, albeit indirectly.  Drag the Exposure Compensation all the way to the left.  If the image is still blank those parts are completely blown in the raw file.  Partial saturation is a little more tricky, but we all know what to look for (color shifts, unnatural desaturation).

                             

                            I think the point is that you're not supposed to have to see it in advance, but rather the recovery process is supposed to give you all you can get.

                             

                            You have to admit, bringing up the image in Camera Raw and looking at a hypothetical new raw histogram vs. bringing up the image in Camera Raw, dragging the EV slider to the left and looking at the image itself and today's histogram aren't worlds apart...

                             

                            That said, if at least one user thinks it could be useful, maybe such a histogram should be provided as a feature or option.  But without further clarification of the request we're all still only guessing at what sbv242 really wants to accomplish.  Maybe he has something entirely different in mind.

                             

                            -Noel

                            • 11. Re: ACR Feature request: RAW Histogram
                              Vit Novak Level 3

                              Agree with that. That's why I added some dashes before and after   --sometimes--

                              • 12. Re: ACR Feature request: RAW Histogram
                                Yammer Level 4

                                Noel Carboni wrote:

                                 

                                Sure it does, albeit indirectly.  Drag the Exposure Compensation all the way to the left.  If the image is still blank those parts are completely blown in the raw file.  Partial saturation is a little more tricky, but we all know what to look for (color shifts, unnatural desaturation).

                                I have noticed that some photos have solid blocks of highlight at any Exposure setting, and suspected that this might be an indication of clipping, but have never accepted this as fact. Now it has been mentioned, I just tried this on a photo which I suspected is partially blown, and I got this. It appears that some patches of sky might be blown, but it's far from clear, and much of the photo is clearly visible. If I hold down the Alt key, I get a few very small highlight warnings at minimum exposure.

                                _KN32343.jpg

                                _KN32343acr.jpg

                                • 13. Re: ACR Feature request: RAW Histogram
                                  Vit Novak Level 3

                                  Yes, negative exposure correction doesn't alter areas with brightness = 1. So what is clipped before applying exposure correction  curve (but after whitebalancing raw data) remains clipped after it.

                                  • 14. Re: ACR Feature request: RAW Histogram
                                    Bill_Janes Level 2

                                    ssprengel wrote:

                                     

                                    If you mean a histogram in terms of the 12-bit or 14-bit or whatever-bit binary numbers for each of the sensor’s photosites without any camera profile or working colorspace applied, then it would always be very skewed left and, in my opinion, relatively useless.

                                     

                                     

                                    I don't agree. Raw histograms are quite useful, and I frequently use the freeware program, Rawnalyze to check my raw files for channel clipping. The green channel usually clips first, but clipping in the red and blue channel may take place in the raw file or with white balance. The appearance of the x-axis of the histogram is determined by the scaling, and log base 2 scaling is useful since it related to f/stops.

                                     

                                    Here is the raw histogram as shown by Rawnalyze. There is no white balance or demosaicing.

                                     

                                    RawnalzeHistogram029.png

                                     

                                    One can also convert the raw file in DCRaw or Iris without white balance or gamma encoding and look at the histogram. I used Histogrammar to se the linear histogram and the log histogram.

                                     

                                    LinearHisto029.png

                                     

                                    LogHistogram029.png

                                     

                                    One can get a good idea of the status of the raw file histogram after white balance and gamma encoding with ACR by setting the controls to linear (sliders on the main tab all set to zero and the tone curve set to linear). It is necessary to adjust for the baseline exposure offset. For the Nikon D3, the value is +0.5 EV, so the image may apper overexposed without this correction.

                                     

                                    ACR_Histo_029.png

                                    • 15. Re: ACR Feature request: RAW Histogram
                                      ssprengel Adobe Community Professional & MVP

                                      Lightroom is a mass-production tool giving feedback about how the output will look.  Lightroom is not a scientific investigative tool to analyze the RAW input data.  

                                       

                                      To the more scientific among us, it is interesting to have all sorts of RAW analysis data at hand, but it really doesn’t help that much in cranking out 100s or 1000s of event photos in a short amount of time.  I enjoy playing with the sorts of programs you mention, but it is beyond the scope of Lightroom to expose this level of RAWness, so-to-speak, so the photographer or photo-processor.

                                      • 16. Re: ACR Feature request: RAW Histogram
                                        areohbee Level 6

                                        Good idea.

                                         

                                        I've noticed the histogram in Lightroom does not accurately show brightest channel, which I've now identified as a problem when auto-toning, which sets tone based on brightest channel, but often makes things too dark as a result. I haven't checked, but darkest channel (not represented on histogram) may be reponsible for Lightroom's auto-toning being too bright sometimes as well.

                                         

                                        Anyway, maybe we'll see the truer histogram along with an RGB curves tool.

                                         

                                        Lightroom is geared toward mass processing large batches of photos, but it needs to have robust single-photo editing tools too... As the saying goes: "if you don't do it, somebody else will..."...

                                        I often fear Adobe's dependence on Photoshop for advanced editing features may be a nail in their Lightroom coffin. As we speak, some powerful company may be working to exploit this achilles-heal. When I'm feeling especially irked about Lightroom's limited develop tools, I often imagine Google buying Bibble and polishing up the UI, improving the quality, and beating Lightroom with a "doesn't require a pixel editor for advanced editing" product. Or PhaseOne getting increasingly serious about the non-PhaseOne-backs market for CaptureOne.

                                         

                                        In the mean time, a hook to open the file in an app that does show a truer histogram may be next best thing. I keep NX2 open when working in Lightroom, for this purpose and others, using the NxToo plugin to launch photos.

                                         

                                        Rob

                                        • 17. Re: ACR Feature request: RAW Histogram
                                          Bill_Janes Level 2

                                          ssprengel wrote:

                                           

                                          Lightroom is a mass-production tool giving feedback about how the output will look.  Lightroom is not a scientific investigative tool to analyze the RAW input data.  

                                           

                                          To the more scientific among us, it is interesting to have all sorts of RAW analysis data at hand, but it really doesn’t help that much in cranking out 100s or 1000s of event photos in a short amount of time.  I enjoy playing with the sorts of programs you mention, but it is beyond the scope of Lightroom to expose this level of RAWness, so-to-speak, so the photographer or photo-processor.

                                           

                                          Quite true, but this is an ACR forum, and ACR/Photoshop is less of a mass production tool. One can use the raw file analysis tools to see how ACR (or Lightroom) handles the raw file. One important point for those who practice ETTR (exposure to the right) is to determine the baseline exposure offset. For my Nikon D3 the value is +0.5 EV. One can use a default esposure of -0.5 EV in ACR.  Otherwise one would think that he is overexposing and might reduce exposure in the camera and not obtain optimal signal to noise.

                                          • 18. Re: ACR Feature request: RAW Histogram
                                            Noel Carboni Level 7

                                            Hey!  Not to go off topic, but I recognize the Carillon at the Chicago Botanical Gardens, Bill. 

                                             

                                            BellTower.jpg

                                             

                                            Butz.jpg

                                             

                                            -Noel

                                            • 19. Re: ACR Feature request: RAW Histogram
                                              ssprengel Adobe Community Professional & MVP

                                              Yeah, I forget which forum I am in, sometimes.  ACR’s histogram is the output colorspace, so I see why you’d also like a histogram of the input colorspace; however, I do think ACR is as much of a production tool as Lightroom is, just more primitive and technical, but not scientific, still.  It is more closely tied to Photoshop, so its histogram is related directly to things Photoshop deals with.

                                              • 20. Re: ACR Feature request: RAW Histogram
                                                Vit Novak Level 3

                                                Ok, added a few lines of code to my program, so if I didn't make any mistakes, here is experimental RAW emulation profile for Canon 40D, so Noel can experiment with it. It does similar thing like "-o 0" switch in dcraw, effectively disabling the color management in ACR.

                                                 

                                                Use the same settings as for my DPP standard profiles for 40D (note that exposure should be -0.24 for 40D and blacks 0). It is intended to be used with output color space sRGB. Histogram will be in raw mode, although scale would not be nor linear nor logarithmic, but using sRGB encoding (gamma) curve. What is clipped in raw after whitebalancing will be clipped here and correctly shown by ACR

                                                 

                                                You will note that image appears flat and desaturated, compared to output in sRGB using various camera profiles

                                                 

                                                http://www.megaupload.com/?d=S5DLHV0Q

                                                 

                                                Profile can be modified for usage with other cameras, by replacing camera name in the profile (whether with dcpTool or exiftool). I also suggest replacing color matrices with matrices for particular camera for proper whitebalancing, although even without that, result will be correct if as shot WB selected in ACR

                                                • 21. Re: ACR Feature request: RAW Histogram
                                                  Bill_Janes Level 2

                                                  Noel Carboni wrote:

                                                   

                                                  Hey!  Not to go off topic, but I recognize the Carillon at the Chicago Botanical Gardens, Bill. 

                                                    

                                                  -Noel

                                                   

                                                  Noel,

                                                   

                                                  It's a small world! Do you live in the Chicago area?

                                                   

                                                  Bill

                                                  • 22. Re: ACR Feature request: RAW Histogram
                                                    Noel Carboni Level 7

                                                    No, but I made sure to visit the Botanical Gardens (several times) when I was there on a business trip a few years ago.  The place is a big, beautiful photo op for sure!

                                                     

                                                    It's an interesting feeling to see a photo of a place you've been.

                                                     

                                                    CBG.jpg

                                                     

                                                    -Noel

                                                    • 23. Re: ACR Feature request: RAW Histogram
                                                      deejjjaaaa Level 2

                                                      one can also use rawconverters like rawtherapee (win / mac / linux) = http://rawtherapee.com/blog/features or rpp (mac / hackintosh / vmware) = http://www.raw-photo-processor.com/RPP/Overview.html, they display raw histogram too...

                                                      • 24. Re: ACR Feature request: RAW Histogram
                                                        w3jxp

                                                        Interesting discussion. In my case I rarely look at the histogram while I'm processing an image. I adjust until it looks right to me on the screen, softproof to see if it will print what's on the screen and then print. I look at the histogram at the start to see if there is any clipping but other wise I adjust until it looks right to me. I trust my eyes and judgment. I do use the histogram on the camera as a tool to help me expose to the right, but it's because it's easer to see on the LCD in the daylight than the image is.

                                                        To get that right I had to test to find out how close to the right I can go without bad things happening. I could adjust the exposure off set I guess but why do it, as I rarely use auto exposure anyway. If I shot birds or sports I might do it differently but my method works for me. In end  there is no one right way to do something, experiment to find what works for you.

                                                         

                                                        John Passaneau

                                                        • 25. Re: ACR Feature request: RAW Histogram
                                                          Bill_Janes Level 2

                                                          Rob Cole wrote:

                                                           

                                                          In the mean time, a hook to open the file in an app that does show a truer histogram may be next best thing. I keep NX2 open when working in Lightroom, for this purpose and others, using the NxToo plugin to launch photos.

                                                           

                                                          Rob

                                                           

                                                          I'm not sure what you mean by "true histogram", but NX2 applies a tone curve to the rendererd raw file, and this curve varies according to the camera control setting. The camera standard setting applies a hot tone curve as can be shown by exposing a uniformly lit surface according to the camera light meter reading. For the D3, this gives 12% saturation, corresponding to an sRGB value of approximately 100 as shown in this Rawnalize analysis of the green channel (which has a white balance multiplier of 1).

                                                           

                                                          Rawnalize01.png

                                                           

                                                          NX2 gives a pixel value of 149 for the green channel, which is much too hot (high).

                                                           

                                                          NX2_CamStd.png

                                                          If you want to get a true value for the status of the raw file, you can also use ACR with a linear tone curve and use an exposure of -0.5 EV to account for the baseline offset that ACR uses for this camera.

                                                           

                                                          ACR_001_Linear_ExpMinus0.5.png

                                                          • 26. Re: ACR Feature request: RAW Histogram
                                                            Bill_Janes Level 2

                                                            w3jxp wrote:

                                                             

                                                            Interesting discussion. In my case I rarely look at the histogram while I'm processing an image. I adjust until it looks right to me on the screen...

                                                             

                                                            John Passaneau

                                                             

                                                            That may work well enough for you, but by ignoring the histogram you may be working with an underexposed image that requires a postive exposure value in ACR. In that case, the signal to noise will be suboptimal. See exposing to the right my Michael Reichman. His rationale of levels in the highlights is incorrect, but his basic thesis is correct.

                                                             

                                                            http://www.luminous-landscape.com/tutorials/expose-right.shtml

                                                            • 27. Re: ACR Feature request: RAW Histogram
                                                              Bill_Janes Level 2

                                                              Noel Carboni wrote:

                                                               

                                                              No, but I made sure to visit the Botanical Gardens (several times) when I was there on a business trip a few years ago.  The place is a big, beautiful photo op for sure!

                                                               

                                                              It's an interesting feeling to see a photo of a place you've been.

                                                               

                                                               

                                                              -Noel

                                                               

                                                              A very nice composition of the Japanese garden. Thanks for posting it.

                                                              • 28. Re: ACR Feature request: RAW Histogram
                                                                areohbee Level 6

                                                                Bill_Janes wrote:

                                                                 

                                                                I'm not sure what you mean by "true histogram"

                                                                Perhaps I should have just said "a different and also useful histogram".

                                                                 

                                                                Sometimes when auto-toning in Lightroom it produces a very dim view. I believe it's due to one channel extending very far right-ward. This can't be seen in Lightroom's version of the histogram for reasons I don't understand, but can be seen looking at the raw in NX2, or looking at the cooked jpeg in ACDSee after exporting from Lightroom... I use the histogram in NX2 sometimes to see things I can't see with Lightroom's histogram.

                                                                 

                                                                I meant no disrespect to Lightroom's histogram - its a very fine and useful histogram...

                                                                 

                                                                Rob

                                                                • 29. Re: ACR Feature request: RAW Histogram
                                                                  areohbee Level 6

                                                                  http://www.luminous-landscape.com/tutorials/expose-right.shtml

                                                                   

                                                                  In theory there is no difference between theory and practice, but in practice, there is...

                                                                   

                                                                  My experience has been that if what's most important in the photo is the lighter tones, then its better to expose to the left, and vice versa.

                                                                   

                                                                  It seems to me that the middle is the "fat" part of the spectrum, lightest *and* darkest tones get slighted (even if they don't appear clipped in camera and/or Lightroom histogram)...

                                                                   

                                                                  On the other hand, I may have arrived at this conclusion erroneously by looking at "untrue" histograms, er I meant "different" histograms - some histograms just don't show everything at the endpoints like others do - I have no technical understanding nor theory to support the observed phenomenon.

                                                                   

                                                                  Rob

                                                                  • 30. Re: ACR Feature request: RAW Histogram
                                                                    w3jxp Level 1

                                                                    I do expose to the right. And I tested to see just how close I could get to the right without overexposing. I've been photographing for a long time and I believe testing more than web articles. One of the great things about digital is that I can test and tryout things to my hearts content with it costing me nothing but my time. When I shot film (slides) there was a little voice in the back of my head that said "21 1/2 cents" every time I pushed the shutter button. And guess what I'm getting better results much more often than with film.

                                                                     

                                                                    John Passaneau

                                                                    "testing beats theory every time"

                                                                    • 31. Re: ACR Feature request: RAW Histogram
                                                                      Noel Carboni Level 7

                                                                      Exposing just up to (but not into) the right edge of the on-camera histogram seems to have worked out for me to be my best practice philosophy (given my gear and my knowledge of what I can do in image processing).  I have, that way, measurement equipment in-hand that stays within its working range.  Something that kisses the right edge of the on-camera histogram may not be under the covers overexposed, but if I simply try to avoid that during shooting I find I get the greatest number of keepers.

                                                                       

                                                                      There are specular highlights in many images, and to have a cloud or a little reflection or something that's bright red come out looking nasty instead of my just being able to dial in some recovery during conversion (taking advantage of the built-in "headroom") seems to me to outweigh the image quality improvement when everything happens to work out right with ETTR off scale.  And when I say "nasty" I am thinking of the stuff I listed in my thread on how the various Camera Raw profiles handle the transition into partial or full overexposure.

                                                                       

                                                                      With relatively modern hardware it's not like image noise is so rampant that I'd cross a threshold from "throw away" to "image perfection" by practicing extreme ETTR anyway.

                                                                       

                                                                      But to each his own.  If you can trust your camera metering to allow you to "overexpose" (per the on-camera measurements) consistently without TRULY overexposing the raw file, then more power to you!

                                                                       

                                                                      -Noel