29 Replies Latest reply on Nov 21, 2012 10:41 PM by Jeff Schewe

    ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?

    Andrew_Hart Level 2

      If I open one of my Canon 5D Mark II CR2 raw files (several in different folders and taken at different times were tested) in ACR (7.2) and save it as a DNG file (with no ACR edits) Bridge shows the DNG as being a 14-bit file whereas if I save it as a PSD file it has a 16-bit depth. Exactly the same thing happens if I convert the CR2 file to DNG using the Adobe DNG Converter (7.2 version). You might answer that as a raw file, it does not yet have a bit depth because it has not been rendered, and the 14-bit description really has no meaning. But if that is the case then Bridge's reporting that all my original CR2 files are 16-bit is also meaningless.

       

      Why is there a difference in the reported, and presumeably actual, bit depths?

       

      Interestingly, if I then open the "Bridge reported"14-bit DNG file in Ps (CS6) and save it as a PSD, the new PSD is shown, presumeably correctly, as being 16-bit.

       

      Please help a poor confused soul.

        • 1. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
          areohbee Level 5

          14 bits of raw recorded by your camera, may be saved in 16-bit rgb file format.

           

          Summary: the bit counts are referring to two different things.

           

          ( you can also save a 12-bit raw in a 16-bit psd file...)

           

          Rob

          • 2. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
            Andrew_Hart Level 2

            Thanks Rob,

             

            But I'm not sure that I fully understand your answer.

            Yes, I do have the 5D2 set to record in 14 bits, but shouldn't that be reflected in the same way by Bridge for both the CR2 and the DNG, which are, after all, both raw files? Why does it draw the distinction?

            • 3. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
              areohbee Level 5

              It's no surprise that the PSD says 16 bits, and I would expect the DNG, assuming it's a raw DNG, to say 14-bits, not 16, which if I read right, it is. The only thing that seems odd is Bridge claiming your CR2s are 16-bits: that I don't understand. Maybe somebody else can explain.

              • 4. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
                ssprengel Adobe Community Professional & MVP

                I can’t explain the 16-bit DNG in Bridge unless it is a linear DNG already demosaiced to a 16-bit RGB TIF, but the PSD is 16-bits because you have ACR set to output 16-bits on the way into Photoshop.

                 

                If you set ACR to 8-bits, then you’ll have 8-bit PSDs from your 14-bit CR2 files which is not want you want.  Perhaps if you set ACR to output 8-bits then your DNGs will be reported as 8-bits in Bridge?

                • 5. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
                  Andrew_Hart Level 2

                  Yes, of course the PSD is 16 bits because I have, as you rightly assumed, ACR set to output at 16 bits.

                   

                  There has never been any mystery about that for me, and I'm sorry if I may have given that impression in my first post.

                   

                  The mystery lies in why Bridge shows my original, unprocessed CR2 files as 16-bit but a DNG conversion directly from the CR2, which is not a linear DNG but rather a full raw DNG, as 14-bits.

                   

                  Once you put the 14-bit DNG through Ps and save it as a PSD it shows up as 16-bit and not 14-bit. That must be because Ps only plays with either 8-bit or 16-bit files and so it pads the 14-bit file to 16 bits and Bridge rightly records it as such.

                   

                  My initial concern was why Bridge distinguishes between the CR2 and the DNG derived/converted from it in terms of bit depth.

                   

                  As a further matter, and something I hinted at in my first post, I can't see how Bridge is able to give any estimate at all of the bit depth of either the CR2 or the DNG. Since they are both raw files and until they have been converted to an RGB file of some sort with a specifically designated bit-depth (either 8 or 16) then they simply exist as data, albeit recorded by the camera at 14 bits, but none of Bridge, ACR or Ps can know in advance at what bit depth you intend to develop either the CR2 or the DNG.

                   

                  Message was edited by: Andrew_Hart

                  • 6. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
                    Noel Carboni Level 7

                    Think about it...

                     

                    At some level the Adobe software knows intimately how many bits have been recorded in the raw file by each and every camera it supports.

                     

                    It sounds as if it's simply trying to give you that information as best it can in several different places, some of which have more accurate information than others.  It's not really surprising that it generates several different but somewhat related status readouts; this is true all across the system.  It may not be presenting as perfectly consistent a story as it could be, but all that info is indeed useful - you just need to get to know what is what, as you are doing here..

                     

                    Oh, and one more thing, and the real reason I posted... 

                     

                    It's important to understand that a raw file containing 14 bit light level measurements for individual photosites isn't directly comparable to a 16 bit RGB file (e.g., a .PSD).  It's more than just 14 vs. 16.  The conversion process does all kinds of complex things, such as de-Bayering to derive color, application of tone curves, deconvolution, ... the list goes on.  It's entirely possible that a 14 bit raw file could be converted into two different 16 bit PSDs that could not be derived from one another, or within which tone curves are applied such there is still data loss - even though there are more bits.  It's just the nature of the beast.

                     

                    I'm not intimately familiar with the DNG standard, but is it possible the bit depth is a value overtly stored by the converter, and which could be easily read out? It's not hard to imagine that once having done that the engineers then had to decide what to display in that place for non-DNG files.  I agree with Andrew that while 14 bits might be an accurate reading of the recorded data, it's hard to justify showing 16.

                     

                    -Noel

                    • 7. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
                      Jeff Schewe Level 5

                      Andrew_Hart wrote:

                       

                      Why is there a difference in the reported, and presumeably actual, bit depths?

                       

                      I think it's the way that Bridge parses the file's metadata...I've got some Canon files that show up as 14 bit, I've got some cameras that show up as 12 bit and others that show as 16 bit. The native raws from these cameras tend to display as 16 bit. Converting them to DNG changes the flag for bit depth (and I think improves the accuracy) and that's when they show up as 12, 14 or 16 bit.

                       

                      Also note that "16 bit" in Photoshop is a misnomer...it's actually 15 bit plus one level for a total rang of 0-32768 for a total of 32769 levels–which is enough precision to contain all cameras' bit depth that I'm aware of. Even my Phase One back doesn't really capture a full and complete 16 bits...it may be slightly more that 14 bit, but it's not a full 16 bit. No camera sensor I'm aware of can...

                       

                      Bottom line is I don't think you really need to worry about the reported bit depth in Bridge for raw files. They are what they are untill you process them in Camera Raw.

                      • 8. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
                        Andrew_Hart Level 2

                        Jeff,

                         

                        What you say makes a lot of sense, and I can now see that there does not seem to be any point in worrying about Bridge's apparently inconsistent reporting on bit depth for raw files.

                         

                        I had forgotten about the 15-bit precision limit of Photoshop. Makes you wonder how much code revision will be necessary for the  Ps engineers when camera sensors start delivering 16-bit capture capability. Perhaps they will elect to throw away the last bit for awhile to give them some breathing space   . In the short time I have been using digital cameras we have gone from 12-bit to 14-bit capture. Surely 16 bits can't be too far off ?

                        • 9. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
                          Andrew_Hart Level 2

                          Noel,

                           

                          This bit of what you wrote I find intriguing:

                           

                          "The conversion process does all kinds of complex things, such as de-Bayering to derive color, application of tone curves, deconvolution, ... the list goes on.  It's entirely possible that a 14 bit raw file could be converted into two different 16 bit PSDs that could not be derived from one another, or within which tone curves are applied such there is still data loss - even though there are more bits.  It's just the nature of the beast."

                           

                          If you are correct, it necessarily implies, I think, that you can get different results each time you convert the same raw file. What's the betting that the Ps engineers, and more particularly the Adobe PR people, would rather we did not start an in-depth discussion of that topic?

                          • 10. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
                            Noel Carboni Level 7

                            Actually, they would love to talk about it - they worked extra hard to ensure it's possible. 

                             

                            I didn't mean to imply it's random, but rather that the many controls can change the results of the conversion quite significantly.  It's far from a trivial process, and the results can be such that data is lost even when converting to a 16 bits/channel image.

                             

                            It's possible that future systems may use 32 bit floating point data for higher accuracy.  I doubt whether Photoshop will ever change its 15 bit +1 implementation to a true 16 bits/channel.

                             

                            -Noel

                            • 11. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
                              Jeff Schewe Level 5

                              Andrew_Hart wrote:

                               

                              If you are correct, it necessarily implies, I think, that you can get different results each time you convert the same raw file.

                               

                              That would be an incorrect implication...the image adaptive nature of Process Version 2012 means that different raw files will have different ranges because of the image adaptive nature of the processing algorithms.

                               

                              However, the same image with the same settings processed multiple times will result in identical processing for that image.

                              • 12. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
                                Andrew_Hart Level 2

                                Jeff Schewe wrote:

                                 

                                  However, the same image with the same settings processed multiple times will result in identical processing for that image.

                                Very glad to have that confirmed, Jeff.

                                • 13. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
                                  MadManChan2000 Adobe Employee

                                  The original raw mosaic data is 14 bits per component, so when you save it as a DNG raw mosaic file, that is what is preserved.

                                   

                                  When you save as a PSD or TIFF, the image has to be converted or rendered, and the choices for bit depth of this output image are 8 bits or 16 bits. 

                                   

                                  So, in one case you are talking about an input (un-rendered) image, and in another case you are talking about an output (rendered) image.  These are two different things, with two different bit depths.

                                  • 14. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
                                    ssprengel Adobe Community Professional & MVP

                                    MMC:  Bridge is reporting 16-bits for some CR2 files when the camera, itself, was set to 14 bits.  This is not obvious from the first post, but is clarified, further down.

                                    • 15. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
                                      Noel Carboni Level 7

                                      "14 bits Per component"...

                                       

                                      I wonder if it might help make things more clear to users if you were to display the actual "bits per pixel" as 14, 24, 48, 96.  This accurately shows, for example, that 8 bits/channel is really 24 bits/pixel, 16 bits/channel is 48 bits/pixel, etc.

                                       

                                      Nah, probably not.  As you point out, the readings from the photosites on an imager aren't really pixels in the strictest sense, so using that terminology would get people into trouble another way.

                                       

                                      There really is no easy way to simplify what you do with Camera Raw into layman's lingo.

                                       

                                      -Noel

                                      • 16. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
                                        Andrew_Hart Level 2

                                        Eric,

                                         

                                        Perusing your post #13 suggests the you've not grasped the thrust of my original and subsequent posts in this thread. Perhaps you haven't had the time to read them thoroughly.

                                         

                                        Undisputed facts: ACR is showing unaltered/unrendered CR2 files as 16-bit and DNG files derived/converted (BUT  STILL UNRENDERED - i.e.  stilled full mosaiced raw and not linear raw) files from the CR2 files using the DNG Converter as 14-bit. Both, as you say, are "input (un-rendered)" files.

                                         

                                        In the first line of your post you at least infer if not actually state that it is perfectly logical for ACR to show the DNGs as 14-bit because that is the bit depth at which the original image was sampled. Well, by the same logic, ACR should also show the CR2s as 14-bit.

                                         

                                        But it doesn't - it shows them as 16-bit, which just has to be unsustainable,  for two reasons. First, it is inconsistent with the bit depth shown for the DNGs. Secondly, since a CR2 has not been rendered to a PSD, TIFF, or whatever other file format, there is no way for ACR to determine whether that rendering will produce an output file in 8 or 16 bits - that is something the user must determine at the time of conversion.

                                         

                                        I had previously agreed with Jeff Schewe's suggestion that perhaps this inconsistency was something that we shouldn't worry about, by inference just be aware of it, accept it and get on with life, but I've changed my mind. The inconsistency initially confused me, and I've no doubt that other ACR users, who've not read and remembered this thread, will continue to be confused in the future. It seems to me that ACR should either show both CR2 and full mosaiced raw DNG as 14-bit (or at whatever bit depth the sampling took place) or show no bit depth at all. I'd rather it showed nothing at all rather than something which is unsustainable or inconsistent.

                                        • 17. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
                                          Jeff Schewe Level 5

                                          Andrew_Hart wrote:

                                           

                                          I had previously agreed with Jeff Schewe's suggestion that perhaps this inconsistency was something that we shouldn't worry about, by inference just be aware of it, accept it and get on with life, but I've changed my mind. The inconsistency initially confused me, and I've no doubt that other ACR users, who've not read and remembered this thread, will continue to be confused in the future. It seems to me that ACR should either show both CR2 and full mosaiced raw DNG as 14-bit (or at whatever bit depth the sampling took place) or show no bit depth at all. I'd rather it showed nothing at all rather than something which is unsustainable or inconsistent.

                                           

                                          Again...it's a Bridge issue, not a Camera Raw issue...in all cases (that I'm aware of) ACR is doing the right thing...how it's reported in Bridge is inconsistant. ACR doesn't (and can't) display anything other than the raw image data (regardless of whether or not it's a DNG), Bridge, on the other hand is not doing the right thing with the display of bit depth.

                                           

                                          Move on...these are not the droids you were looking for...(meaning it ain't no big thing).

                                          • 18. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
                                            Yammer Level 4

                                            Jeff Schewe wrote:

                                             

                                            Again...it's a Bridge issue, not a Camera Raw issue

                                            Off topic, and wistfully thinking out loud: wouldn't it be nice if those smart Camera Raw people spent some time helping the Bridge people with some of their niggly Raw-handling shortcomings, like pointless re-caching, soft previews, additional filters, better metadata panel, etc.?

                                             

                                            • 19. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
                                              Andrew_Hart Level 2

                                              Jeff Schewe wrote:

                                               

                                              Again...it's a Bridge issue, not a Camera Raw issue... Bridge, on the other hand is not doing the right thing with the display of bit depth.

                                               

                                               

                                              Yes, I gave some thought to that before my last post #16. I wondered if indeed Bridge was the culprit and concluded that it probably was not.

                                               

                                              In this forum in the past there has been repeated discussion about the thumbnails displayed by Bridge. First it uses the embedded JPEG in the raw file which is quickly replaced by a thumbnail generated by ACR - presumably according to the default settings in ACR, that is, what Bridge finally displays is a thumbnail of the converted raw.

                                               

                                              If you are correct, then we must conclude that ACR does not pass any information to Bridge about the bit depth it has used in converting the raw and making that thumbnail, but leaves it up to Bridge to decide.

                                               

                                              I thought that unlikely, in particular because of the observed behaviour of the DNG Converter. If you convert a CR2 sampled at 14 bits to DNG using the converter you get a file that Bridge says is 14 bits, which Eric Chan has told us is logical and perfectly correct. Did Bridge make up its own mind about that bit depth and got it right but when looking at the CR2 it says it's 16 bits and gets it wrong, or did Bridge really get its bit depth information from the DNG Converter for the DNG and from ACR for the CR2?

                                              • 20. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
                                                Andrew_Hart Level 2

                                                Yes, and one more thing.

                                                 

                                                I was myself forgetting my original post which spoke about converting the CR2 to DNG using ACR, not the DNG Converter, and getting a Bridge report of 14 bits for the DNG whereas 16 bits for the untouched CR2.

                                                My point: both ACR and the DNG Converter have Bridge reporting 14 bits for the converted (but not rendered, that is, not demosaiced) DNG.

                                                Just wanted to make that clear.

                                                • 21. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
                                                  MadManChan2000 Adobe Employee

                                                  The issue is that non-DNG raw files like CR2 do not have standard ways of reporting bit depth in a way that general file browsers like Bridge can easily read.  (This is related to Jeff's comment above.)  In contrast, when converted to DNG, the header of the DNG does contain the appropriate bit depth of the mosaic image data (in the standard TIFF header location) and hence can be reported properly.

                                                  • 22. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
                                                    Andrew_Hart Level 2

                                                    Eric,

                                                     

                                                    But that can't be the whole story.

                                                     

                                                    If I remember correctly, the preview/thumbnail of the CR2 that you are looking at in Bridge is actually the preview/thumbnail of a TIFF - the result of ACR's rendering of the CR2 in accordance with the default conversion settings of ACR. I'm pretty sure that the previous sentence is correct as its a point that has been made in this forum several times in the past. 

                                                     

                                                    So if the DNG shows the correct bit depth stored in, as you say, "the standard TIFF header location", why can't the CR2, now rendered as a TIFF, do the same?

                                                     

                                                    This logic seems to me to be strengthened further by the fact that, as we all know, there is no viewing of a raw file without rendering. So when viewing a preview/thumbnail of a DNG in Bridge, you aren't actually viewing the DNG at all, you are viewing a preview/thumbnail of something which has been demosaiced, had a tone curve applied to it, et cetera, namely, I presume, another TIFF. If that TIFF can report its correct bit depth to Bridge, then why not the TIFF rendered from the CR2 as well?

                                                    • 23. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
                                                      Jeff Schewe Level 5

                                                      Andrew_Hart wrote:

                                                       

                                                      But that can't be the whole story.

                                                       

                                                      Well, as it relates to Bridge, is is...as Eric said, the bit depth reported to Bridge is non-standard unless the file has been processed as DNG.

                                                      Andrew_Hart wrote:

                                                       

                                                      So if the DNG shows the correct bit depth stored in, as you say, "the standard TIFF header location", why can't the CR2, now rendered as a TIFF, do the same?

                                                       

                                                      Because...Bridge isn't reporting the correct info (which I tried to explain and you seem to refuse to accept)...

                                                       

                                                       

                                                      Andrew_Hart wrote:

                                                       

                                                      This logic seems to me to be strengthened further by the fact that, as we all know, there is no viewing of a raw file without rendering. So when viewing a preview/thumbnail of a DNG in Bridge, you aren't actually viewing the DNG at all, you are viewing a preview/thumbnail of something which has been demosaiced, had a tone curve applied to it, et cetera, namely, I presume, another TIFF. If that TIFF can report its correct bit depth to Bridge, then why not the TIFF rendered from the CR2 as well?

                                                       

                                                      Because, well, the headers are not standard and Bridge kinda reads the wrong thing with many raw/rendered files (unless you convert to DNG).

                                                       

                                                      Not sure why this is so hard to understand...Bridge is a browser app that tries (but often fails) to display the "right thing". But often can't due to the file's metadata.

                                                       

                                                      This really is not a thing to dwell on...you may think there is a tempest is a teapot, but it means nothing. Again, these are not the droids you were looking for (do you even understand the reference-Google it).

                                                       

                                                      This whole thing is a red herring...you may as well give it up. Seriously, you are not getting anywhere here...raw is raw and you should generally ignore Bridge for most reports...because, well, Bridge isn't accurate because the standards for reporting bit depth are not standard...that's what is causing the differences. [Edited to keep this thread a friendlier place.]

                                                       

                                                      Message was edited by: TerriStoneCHL

                                                      • 24. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
                                                        Yammer Level 4

                                                        Jeff Schewe wrote:

                                                        Again, these are not the droids you were looking for (do you even understand the reference-Google it).

                                                        Erm ... I may be missing the joke, but ... didn't Obi Wan say this because they WERE the 'droids they were looking for?

                                                        • 25. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
                                                          Jeff Schewe Level 5

                                                          Ah, so, paying attention you were, young knight....

                                                          • 26. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
                                                            Noel Carboni Level 7

                                                            [Edited to keep this thread a friendlier place.]

                                                             

                                                            Message was edited by: TerriStoneCHL

                                                            • 27. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
                                                              Jeff Schewe Level 5

                                                              The OP found inconsistancies with the way Bridge reported bit depth...as Eric has confirmed, this is an issue with the way some files' headers are written into the proprietary raw filse and the inconsistancies in which Bridge reports those results. The OP then went down a rabitt hole that was compeltely wrong headed...

                                                               

                                                              [Edited to keep this thread a friendlier place.]

                                                               

                                                              Message was edited by: TerriStoneCHL

                                                              • 28. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
                                                                TerriStone Adobe Employee

                                                                Noel Carboni and Jeff Schewe, please remember that when the language of your posts get personal, those posts have gone too far.

                                                                 

                                                                You are both valuable contributors to the forums, but the kind of exchanges that were in this thread before I edited it help no one.

                                                                • 29. Re: ACR conversion of CR2 to DNG = 14-bit Not 16-bit :Why?
                                                                  Jeff Schewe Level 5

                                                                  The bottom line for this thread is: don't rely on Bridge to report an exact bit depth with proprietary raw files...DNG's are correct but other propriety raw file formats may not be…YMMV (your milage may vary) and what is reported in Bridge is, at best an approximation and not to be relied on completely.