11 Replies Latest reply on Dec 5, 2007 10:27 PM by Jann Lipka

    Phase One P45 pixel count mess with ACR 4.3

    Jann Lipka Level 1
      I shoot with P45 plus and I'm trying to get exactly the same pixel size when processing
      with P45 as with Capture .

      The problem is that there is some pixels difference, so proper alignment is not possible .

      Looks like pixel proportions in ACR are wrong ( after all it is a Phase digital back )
      ( It could be that ACR sees some " hidden " pixels or similar " feature" )

      I want to process some files both in ACR ( for color ) and in Phase One
      ( for moire reduction )
      Any suggestions / workarounds ?
        • 1. Re: Phase One P45 pixel count mess with ACR 4.3
          michael shaffer Level 1
          The source of the problem (ie, mismatch) must be the individual demosaicing algorithms. The process uses neighboring raw "pixels" for creating a specific RGB pixel, and therefore the algorithms will toss pixels near the edge.

          If you were to capture an image for which registering the P1 RGB with the ACR RGB could be done accurately and precisely, then you'd have overlay numbers that you'd be able to write an action or script for.

          hth :o)
          • 2. Re: Phase One P45 pixel count mess with ACR 4.3
            Panoholic Level 2
            The Phase One P45+ creates an image of 7248x5441 pixels. Strange, for the CFA is 2x2, so I would expect the dimensions to be even numbers, but that's how they do it.

            The active image size is 7216x5412, according to the specs at Phase One. However, the DNG converter creates a file stating, that the active area is 7248x5441, and the default crop size is 7240x5433. I guess this latter is the size, which will be generated by ACR - is that so, Jann?

            It is noteworthy, that the Phase One specification is incorrect (or they have a different understanding of "active pixels"); *all* pixels of the 7248x5441 image are active, i.e. carrying image data. However, their specification is somewhat logical: at least 7216 is a multiple of 8, and the proportion is 4:3.

            So, the DNG converter (and then ACR as well) is correct about the active size, but the crop size is a mess. The 4:3 proportion should be kept, and the best would be to do it as Phase One specifies, namely 7216x5412.
            • 3. Re: Phase One P45 pixel count mess with ACR 4.3
              Jann Lipka Level 1
              On Capture forums I got an answer saying -
              it is our back so we know ....

              I'm sure if this back would be as popular as some DSLR , Adobe would definetely
              change ACR behaviour to comply with camera makers specs ...
              What I get from ACR is 7240x5433 and Phase gives 7230x5428 ,

              From what I see I cannot just stretch on image into another ( changing proportions ) so there must be some cropping . Anyone with tip how to get a fit of those two ?
              • 4. Re: Phase One P45 pixel count mess with ACR 4.3
                Panoholic Level 2
                > On Capture forums I got an answer saying it is our back so we know

                BS. It is their back, and they have something in the specs and create something different. Plus they too don't have a pocket calculator to verify if the result is in 4:3.

                Stretching is of course an absurd idea, but it is very easy to create an action in PS to crop the ACR image. I don't know if and how it is possible directly in ACR, automatized.

                However, first you should overlay the two images to determine the position of the smaller C1 image on the ACR one. It is not self-evident, that you need to crop starting from the top left position.
                • 5. Re: Phase One P45 pixel count mess with ACR 4.3
                  Jann Lipka Level 1
                  OK Now I can see that probably a crop of the larger ACR image would do ...from what I see it is not symetrical at all ..
                  Actually it looks like Capture gives one more pixel of image more in down direction .
                  ACR give 6 pixels more at the top ( so it makes total of five ) , 9 px to the right
                  and 1 to the left

                  I don't like it at all .
                  But I could align images in " difference " mode ..
                  Thanks
                  • 6. Re: Phase One P45 pixel count mess with ACR 4.3
                    Panoholic Level 2
                    1. Create the C1 image first and open it PS,

                    2. pass the ACR image to PS,

                    3. copy the ACR image as a layer on top of the C1 image,

                    4. align them and flatten.

                    The last line, which is "missing" from the ACR image will be taken over from the C1 image. Now you have a C1 sized, complete ACR image.
                    • 7. Re: Phase One P45 pixel count mess with ACR 4.3
                      Mathias Vejerslev Level 2
                      Hi Jann,

                      If its just for a couple of pictures, and its the crop that differs, you can just overlay them in photoshop, then align them with Align Layers, do your masking, flatten.
                      • 8. Re: Phase One P45 pixel count mess with ACR 4.3
                        Jann Lipka Level 1
                        I would prefere manual nudge when possible instad of auto align , because most of the time
                        align would warp image meaning a small loss of sharpness, so in this case I
                        will use my arrow keys:-) ( it is faster too )
                        • 9. Re: Phase One P45 pixel count mess with ACR 4.3
                          Mathias Vejerslev Level 2
                          It might be faster for the first couple of images, but Align Layers (Perhaps Photomerge with the reposition only option - no warping), could be automated for batching, I guess.

                          Or how about setting up a crop in ACR that corresponds exactly to Capture1? Once you get it right, you can save the settings.
                          • 10. Re: Phase One P45 pixel count mess with ACR 4.3
                            Mathias Vejerslev Level 2
                            You could also do the crop inside Photoshop if that is easier, an action could be made to do this.
                            • 11. Re: Phase One P45 pixel count mess with ACR 4.3
                              Jann Lipka Level 1
                              Mathias, Within ACr will nort work as Capture gives one more pixel down ,
                              OTOH inside PS should work ..
                              THanks for a good idea .