31 Replies Latest reply: Mar 10, 2013 3:53 PM by trshaner RSS

    In which order is the raw file rendered?

    radeldudel Community Member

      As far as I understand (and can measure), in the develop module Lightroom renders the picture in stages and can cache the image state of a stage so future changes can be rendered faster.

       

      This sounds confusing, lets start simpler:

       

      When I have an image with a lot of local corrections and I change some basic setting light brightness, dynamics, saturation, Lightroom will render the change quite fast, usually in about half a second.

       

      If, on the very same picture, I change the noise reduction setting it will take Lightroom several seconds to render and update the image on the screen!

       

      So it seems Lightroom caches the result of the noise reduction and when I change a basic setting it does not need to render the noise reduction anew, it just can take a cached image and work from there.

       

      And I would like to know which cached stages exist in the current version of Lightroom and in what order they are rendered.

       

      Is this information available somewhere? Or at least some hint about the order in which an image is rendered internally, this would help me a lot!

       

      Thanks!

      Sam

        • 1. Re: In which order is the raw file rendered?
          Jeff Schewe Community Member

          radeldudel wrote:

           

          Is this information available somewhere? Or at least some hint about the order in which an image is rendered internally, this would help me a lot!

           

          No, and it's actually a lot more complicated than you think and exactly how the ACR/LR pipeline works is proprietary info and unlikely to be disclosed.

          • 2. Re: In which order is the raw file rendered?
            DdeGannes CommunityMVP

            The official position is as Jeff describes, this question has been asked many times and details have not been made public.

             

            All the producers of software for the processing of RAW data from digital cameras adopt the same approach, the camera manafacturer, other third party providers like Adobe, DxO, Capture One, Silkypix, DCRAW, ACDC Pro, AfterShot Pro etc.etc.etc. all have proprietory processes that they will not disclose, period.

             

            That said, I have used Lightroom since the Beta of version one and afaik

            1. Lightroom has a specific order for applying the rendering of development adjustments, irrespective to the order they are applied by you.

            2. On import of images Lightroom applies the import defaults and presets (if selected) and creates Preview data files which are used by Lightroom to display the images in modules other than the Develop Module. Lightroom also creates info in the ACR Cache folder which is used to assist the develop module in rendering and displaying the image.

            3. When you are working on an image in the develop module the original image is rerendered each and every time you make a change, re-applying all the process in the prescribed order. This is why moving between files in this module takes more time than the Library Module.

            4. There are a number of edits that take longer to process by the very complex nature and how they affect other processes. e.g. Lens correction, Noise reduction, and are better done in the latter part of your editing.

            I have tried to make this simple an short, just to get to the point. Get the simple processes out of the way first, then work on the complex finesse issues last.

            Just an opinion.

             

            One other point, do not think Photoshop, Lightroom is not Photoshop and requires a completely different thought process. Photoshop makes the change in the order you choose, Lightroom makes their own choice.

            • 3. Re: In which order is the raw file rendered?
              areohbee Community Member

              DdeGannes wrote:

               

              3. When you are working on an image in the develop module the original image is rerendered each and every time you make a change, re-applying all the process in the prescribed order.

              This statement may need some editing in order to be correct as worded.

              • 4. Re: In which order is the raw file rendered?
                DdeGannes CommunityMVP

                OK, how do you think it should be worded. "in the designed order"?

                • 5. Re: In which order is the raw file rendered?
                  areohbee Community Member

                  It takes multiple seconds to do what you describe (rerender entirely, from scratch, re-applying all the process in the prescribed order), so I don't see how it could (or why it would) do that for every little tweak you make.

                   

                  I'm drawing my conclusion based on observation and limited understanding - I could be wrong.

                  • 6. Re: In which order is the raw file rendered?
                    DdeGannes CommunityMVP

                    Its just my understanding of how it works. Somehow the ACR cache assists in the process. The other option would be to update and use the preview.

                    • 7. Re: In which order is the raw file rendered?
                      radeldudel Community Member

                      Jeff Schewe schrieb:

                       

                       

                      No, and it's actually a lot more complicated than you think and exactly how the ACR/LR pipeline works is proprietary info and unlikely to be disclosed.

                       

                      A pity. For speed it matters if I work with or against some kind of order and information about this would be helpful.

                      • 8. Re: In which order is the raw file rendered?
                        radeldudel Community Member

                        DdeGannes schrieb:

                         


                        4. There are a number of edits that take longer to process by the very complex nature and how they affect other processes. e.g. Lens correction, Noise reduction, and are better done in the latter part of your editing.

                        I have tried to make this simple an short, just to get to the point. Get the simple processes out of the way first, then work on the complex finesse issues last.

                        Just an opinion.

                         

                        My opinion differs: For example when I change noise reduction on a fresh image Lightroom will refresh the image quite fast in under a second.

                        The more other "simple" adjustments the image has, the slower noise reduction will become.

                         

                        But it does not work the other way round: The speed of the simple adjustments does not slow down as much as the noise reduction.

                         

                        So if I follow your advice and do the simple adjustments first, then the complex like noise reduction Lightroom will be slow when doing the complex stuff. But if I do noise reduction first, then the simple adjustments it will be fast enough through the whole process, since there seems to be some kind of cache for the "first stages" (or whatever Lightroom does here).

                         

                        Thats why I'm looking for more information about the intended workflow.

                        • 9. Re: In which order is the raw file rendered?
                          radeldudel Community Member

                          Rob Cole schrieb:

                           

                          It takes multiple seconds to do what you describe (rerender entirely, from scratch, re-applying all the process in the prescribed order), so I don't see how it could (or why it would) do that for every little tweak you make.

                           

                          I'm drawing my conclusion based on observation and limited understanding - I could be wrong.

                           

                          Same here. Some adjustments are faster than a complete recomputation of the image, so there must be some kind of caching at work.

                           

                          It would be nice if Adobe gave us some advice how to use this to our advantage instead of working against it.

                          • 10. Re: In which order is the raw file rendered?
                            areohbee Community Member

                            radeldudel wrote:

                             

                            Some adjustments are faster than a complete recomputation of the image, so there must be some kind of caching at work.

                            Most definitely.

                             

                             

                            However, I suspect Jeff Schewe is right on both counts:

                            * More complicated than we might imagine.

                            * Adobe shan't try to elaborate.

                             

                            Sometimes said algorithm is tweaked on a per dot-release basis, in the quest for improved performance and reliability/stability, which is probably one of the reasons new dot releases perform better for some folk (or in some ways), and worse for others (or in some ways).

                             

                            Anyway, there have been user recommendations when things were noted about how one adjustment affects speed in general, or speed of other adjustments in particular, but I've never followed nor scrutinized, so I don't know...

                             

                            Good luck,

                            Rob

                            • 11. Re: In which order is the raw file rendered?
                              radeldudel Community Member

                              Rob Cole schrieb:

                              Most definitely.

                               

                              However, I suspect Jeff Schewe is right on both counts:

                              * More complicated than we might imagine.

                              * Adobe shan't try to elaborate.

                               

                              Yep! And performance varies between starts, too. I've had runs when a defined action on a specific picture took more than 2s to compute (10 times in a row) and times when it took about 1s to compute (also 10 times in a row).

                              So it seems Lightroom has a very human quality: Off-Days

                               

                              But it's a pain to wait whopping 10s for Lightroom to switch (and fully load) from one image to the next in develop mode. I wonder what kind of computer is fast enough to really fly in LR4.

                               

                              Thanks,
                              Sam

                              • 12. Re: In which order is the raw file rendered?
                                Jeff Schewe Community Member

                                radeldudel wrote:

                                 

                                A pity. For speed it matters if I work with or against some kind of order and information about this would be helpful.

                                 

                                As it relates to the order a user does something, there are general rules...if you are going to do lens corrections, it's better to do them before doing tones of spot healing or local adjustments because if done first, the local brush masks and spot healing must them be warped the same as the lens corrections-which can slow down ACR/LR considerably...

                                 

                                Noise reduction–depending on the preview size can also have an impact of screen refresh of adjustments made after the noise reduction has been set because ACR/LR is previewing the noise reduction (to the size of the preview) and then trying to update the additional adjustments...you can, in LR, turn off the Detail panel adjustments by sliding the preview slider to off–this will speed up refresh of additional adjustments, but you'll need to remember to turn the Detail panel back on after making the other adjustments...

                                 

                                There are factors that impact performance...obviously, multiple real cores helps, so does ram (up to a point) and really fast drives. The size of the LR display window impact performance too. Using LR full screen on a 30" display is going to slow down refresh because more screen pixels must be calculated than with say a 24" display.

                                 

                                Everything seems to impact everything...but I wouldn't worry too much about the exact order of the raw processing pipeline because, well, you can't change it and Adobe is unlikely to disclose what it's doing when and why.

                                • 13. Re: In which order is the raw file rendered?
                                  radeldudel Community Member

                                  Jeff Schewe schrieb:

                                   

                                  if you are going to do lens corrections, it's better to do them before doing tones of spot healing or local adjustments because if done first, the local brush masks and spot healing must them be warped the same as the lens corrections

                                  Uh, this is interesting! So there is a difference between first doing local adjustments, then lens correction or the other way around? Or, in other words: Does the order of corrections matter in this case because it will lend to different results (and speed)?

                                   

                                  As for the rest. Lightroom is slow since I got a D800e and an Eizo CG303w - both high in pixel count. The computer is a core i7 with 16GB Ram, two SSDs for system, Lightroom catalogue and temp files. I'll swap it for a Xeon in the next days, hope this helps...

                                   

                                  The hint about doing detail adjustment, then switching it off is a nice one, thanks!

                                  • 14. Re: In which order is the raw file rendered?
                                    D Fosse Community Member

                                    Have you tried the 4.4 release candidate? I'm curious.

                                     

                                    4.4 RC seems much snappier than 4.3 on one of my two machines, to the point where it now really feels hardware-limited, as it should, instead of "something else" getting in the way. (Also D800, but smaller monitor).

                                    • 15. Re: In which order is the raw file rendered?
                                      Jeff Schewe Community Member

                                      radeldudel wrote:

                                       

                                      Uh, this is interesting! So there is a difference between first doing local adjustments, then lens correction or the other way around? Or, in other words: Does the order of corrections matter in this case because it will lend to different results (and speed)?

                                       

                                      Different speeds, yes...but the rendered results should be the same. If the adjustment brush masks and spot healing is done before distortion correction, LR must render the masks and spot healing as placed in the uncorrected image and then transform them to correct for the lens corrections. This has an impact on the speed because of the difference in pre and post lens corrections.

                                       

                                      The pipeline is the pipeline and the results should always be the same no mater what order you do them in, but the order the user makes adjustments can have an impact on performance...but...

                                       

                                      The ONLY thing I can think of that is literally order dependent is the order you put spot healing points down...if you place one down and then do another point with a slight overlap, the order that you place them will change the results...

                                      • 16. Re: In which order is the raw file rendered?
                                        Lee Jay Community Member

                                        Red eye detection is also dependent on the current state.

                                        • 17. Re: In which order is the raw file rendered?
                                          radeldudel Community Member

                                          Jeff,

                                          thanks for the information!

                                           

                                          One related question, though: When you switch to some other image in Develop, the display will update three times: After ~0,5s it will show the preview, after ~2-3s it will show some blurry version of the final image and after 6-10s it will show the final image (and in develop it seems to have no impact if you have 1:1 previews).

                                           

                                          Why is the blurry image shown? And why is it blurred?

                                          • 18. Re: In which order is the raw file rendered?
                                            trshaner CommunityMVP

                                            I can't tell you why, but I did run a few tests here:

                                             

                                            http://forums.adobe.com/message/5094278#5094278

                                             

                                            Using LR defaults with no NR etc. browsing images takes about .5 sec. on my system to reach maximum sharpness. Add Luminance NR and that goes up to 1.0 sec. Add Luminance NR and Defringe and it goes up to 1.5 sec. My guess is that you are seeing different image building stages onscreen.

                                             

                                            Another interesting rendering order I would like to point out is that LR applies the Local Tone controls prior to the Global Tone controls:

                                             

                                            http://forums.adobe.com/message/4612100#4612100

                                             

                                            This has ramifications to the image dynamic range. Any Local control setting that increases image highlights runs the risk of creating unrecoverable clipped highlight areas. Try the test outlined at the above link and read the other comments further down.

                                             

                                            The takeaway here is to use the Local controls in the direction of reducing highlights and increasing shadow areas. This has no impact that I am aware of concerning LR's speed, but it is something you should be aware of when making Local adjustments.

                                            • 19. Re: In which order is the raw file rendered?
                                              radeldudel Community Member

                                              Using LR defaults with no NR etc. browsing images takes about .5 sec. on my system to reach maximum sharpness. Add Luminance NR and that goes up to 1.0 sec. Add Luminance NR and Defringe and it goes up to 1.5 sec. My guess is that you are seeing different image building stages onscreen.

                                               

                                              When I reduce the size of the LR window (or the screen resolution) the process will speed up a whole lot!

                                              My main speed bump seems to be my screen size of 2560x1600 - in smaller resolution the three-step-update-process can't be seen as good as in this resolution.

                                               

                                              I wonder how Lightroom fares on Retina-displays.

                                              • 20. Re: In which order is the raw file rendered?
                                                Lee Jay Community Member

                                                Try 1:4 size.

                                                • 21. Re: In which order is the raw file rendered?
                                                  trshaner CommunityMVP

                                                  radeldudel wrote:

                                                   

                                                  I wonder how Lightroom fares on Retina-displays.

                                                   

                                                  The higher the display resolution the longer it will take to render the screen preview. It's should be proportional to the screen Megapixels:

                                                   

                                                  1280x1024 =  1.3 Mp

                                                  1920x1080 = 2.1 Mp

                                                  1920x1200 = 2.3 Mp

                                                  2560x1440 = 3.7 Mp

                                                  2560x1600 = 4.1 Mp (Retina 13" Display)

                                                  2880x1800 = 5.2 Mp (Retina 15" Display)

                                                   

                                                  Based on these numbers I would expect the Retina 13"  to be 2x slower than a 1920x1080 display resolution and the Retina 15" about 2.5x slower.

                                                   

                                                  You can easily control this by pulling in the right, left and bottom film strip panels to make the center preview image smaller. Unfortunately on a 13" or 15" Retina screen the preview image is going to be fairly small, which is not too helpful.

                                                   

                                                  Until Adobe adds GPU acceleration to LR to speed up preview rendering there isn't much else we can do. A faster processor helps, but as we well know some systems with fast processors are still slow.

                                                  • 22. Re: In which order is the raw file rendered?
                                                    radeldudel Community Member

                                                    Lee Jay schrieb:

                                                     

                                                    Try 1:4 size.

                                                     

                                                    1:4 makes a small difference: 8.3s instead of 8.7s. Fits, since the image is a bit smaller.

                                                     

                                                    When I use smaller resolution I only get two update phases. But at 2560x1600 I get the same update process as if I would be using the 1:1 view.

                                                    • 23. Re: In which order is the raw file rendered?
                                                      radeldudel Community Member

                                                      trshaner schrieb:

                                                       

                                                      It's should be proportional to the screen Megapixels:

                                                       

                                                      Yep, it should - and I'd love to know if it is in practice with retina displays or if in these cases there is some other magic at work.

                                                       

                                                      Funny side note about fast computers: In develop (fit view) My Xeon 1620 takes 8s to show an image, while my subnotebook (Low-Voltage Intel Core2Duo L9300 1,6Ghz) just needs 4s to achieve this, since it's resolution is way smaller.

                                                      • 24. Re: In which order is the raw file rendered?
                                                        trshaner CommunityMVP

                                                        The MacBook Pro with Retina display uses two graphics processors:

                                                         

                                                        1) Integrated Intel HD 4000 using system memory

                                                        2) High-Performance NVIDA GeForce GT 650M with 1GB of GRAM

                                                         

                                                        It automatically switches between them depending on the application being run, I assume to save power. Since LR currently does NOT support any type of GPU acceleration its performance is the same regardless of which graphics processor is being used.

                                                         

                                                        See test here:

                                                         

                                                        http://forums.adobe.com/message/5094278#5094278

                                                         

                                                        You can "scale" Retina displays to reduce the resolution by 1/2 (1/4 Mp). This would increase LR's performance considerably at the expense of losing the Retina fine resolution capability.

                                                         

                                                        IMHO using Retina's 2x display resolution with LR isn't going to help you make better image adjustments, so scaling makes good since. For image "viewing" you can use the multitude of applications already provided and/or supported on Retina based Mac products.

                                                         

                                                        Anyone here care to comment on their MacBook Pro with Retina display performance using LR 4.3/4.4?

                                                        • 25. Re: In which order is the raw file rendered?
                                                          Lee Jay Community Member

                                                          radeldudel wrote:

                                                           

                                                          trshaner schrieb:

                                                           

                                                          It's should be proportional to the screen Megapixels:

                                                           

                                                          Yep, it should

                                                          No, it shouldn't.  There are discrete rendering sizes - 1:1, 1:2, 1:4, 1:8 etc.  If you're in between two of those, it renders at the next higher one.  Each one should be 4 times as fast as the previous.

                                                          • 26. Re: In which order is the raw file rendered?
                                                            radeldudel Community Member

                                                            Lee Jay wrote:

                                                             

                                                            radeldudel wrote:

                                                             

                                                            trshaner schrieb:

                                                             

                                                            It's should be proportional to the screen Megapixels:

                                                             

                                                            Yep, it should

                                                            No, it shouldn't.  There are discrete rendering sizes - 1:1, 1:2, 1:4, 1:8 etc.  If you're in between two of those, it renders at the next higher one.  Each one should be 4 times as fast as the previous.

                                                             

                                                            The surprising thing: It's none of both - the speed gain is neither proportional to size nor to next render size (if there is something like this).

                                                            At least not when I measure it.

                                                            • 27. Re: In which order is the raw file rendered?
                                                              trshaner CommunityMVP

                                                              Lee Jay is correct. The speed difference should be in 4x steps proportional to the standard pyramid view sizes (1:1, 1:2, etc.).

                                                               

                                                              For 5D MKII files these are the display image sizes:

                                                               

                                                              1:1  5616x3744

                                                              1:2  2808x1872

                                                              1:4  1404x936

                                                              1:8  702x468

                                                              1:16 351x234

                                                               

                                                              On my 1920x1080 display based system 1:16 views (351x234) take just as long as the 1:2 view size (2808x1872) when browsing in full-screen mode in the Develop module. It isn't until 1:1 view size (5616x3744) that I see a difference and it is 4x. Why it's not proportional to the actual pyramid view size steps I have no idea.

                                                               

                                                              So you can improve the browsing speed by reducing the image size. Once you hit the "speed bump" display size you should see a 4x speed up in screen rendering.

                                                               

                                                              Cheers,

                                                               

                                                              Todd

                                                              • 28. Re: In which order is the raw file rendered?
                                                                Lee Jay Community Member

                                                                I was talking about frame rate when moving sliders, not image to image time.

                                                                • 29. Re: In which order is the raw file rendered?
                                                                  trshaner CommunityMVP

                                                                  I just tried the effect of image size on moving sliders using the worst case with Luminace NR and Defringe tool applied and I'm only seeing a 2x difference between 1:16 and 1:1 views (i.e. four pyramid steps).

                                                                   

                                                                  I'm sure this has to do with how the Camera Raw Cache file speeds up image building in the Develop module during real-time image adjustments. In the case of "browsing" in the Develop module it doesn't appear to help as much since I'm seeing a 4x difference.

                                                                   

                                                                  Try it for yourself and let me know what you see. These things tend to be system specific so all bets are off that your Develop module behavior will match mine (i.e 2x sliders and 4x browsing at 1:16 vs 1:1 views).

                                                                  • 30. Re: In which order is the raw file rendered?
                                                                    Lee Jay Community Member

                                                                    I'm talking about global sliders like exposure.  Things like CA may have to work on the full size, I'm not sure.

                                                                    • 31. Re: In which order is the raw file rendered?
                                                                      trshaner CommunityMVP

                                                                      Sorry. I was referring to the White Balance slidersTemp and Tint slider response, which is worst case with Luminnce NR and Defringe settings. I guess you can find many variations as to what slows things down and which controls are affected. The point I was trying to make is that none of the controls exhibit a 4x response increase for each pyramid step. Agreed?