6 Replies Latest reply on Jul 29, 2008 12:01 AM by Ramón G Castañeda

    ACR 4.4.1 opening 8-bit TIFFs as 16-bit TIFFs

      I have a number of 8-bit sRGB TIFFs produced from scans of 35mm colour slides by the Epson Perfection 4990 Photo scanner. Am using Win XP Pro SP3.

      If I open these images from Bridge 2.1.1.9 directly in Ps CS3 10.0.1 they are correctly shown in File Info and at the top of the Ps file view window as being 8-bit sRGB TIFFs.

      However, if I open these from Bridge into ACR 4.4.1 (using either CTRL+R or File/Open in Camera Raw) they are shown (in the blue text at the bottom of the view window) as being 16-bit sRGB TIFFs.

      Further, if, whilst in ACR, I choose Open Image to open any one of these images in Ps, Ps then says that the image is 16-bit - that is, it now agrees with ACR. If I then save the image as a TIFF (whether or not any adjustments were made in ACR), Ps saves it as 16-bit which nearly trebles the file size (18 to 47 MB).

      Anyone have any idea as to why this might be happening?
        • 1. Re: ACR 4.4.1 opening 8-bit TIFFs as 16-bit TIFFs
          Ramón G Castañeda Level 4
          You have it set that way, Andrew. :)

          Click on the Output Preferences (the underlined blue row of settings that appears just under the preview in ACR) to bring up the options menu and change it to 8 bits.

          Whatever you set there will "stick" for any file(s) you open later, so make sure you mind that setting whenever you want 16 bits later on or vice versa.
          • 2. Re: ACR 4.4.1 opening 8-bit TIFFs as 16-bit TIFFs
            Level 1
            Thank you, Ramon.

            Your answer seems obvious, now that I think about it. Bit of a nuisance that you have to monitor these settings. Seems like ACR should be able to tell the bit depth of a file (like Ps can) without having to be told.

            One further curiosity. Even if no adjustments are made in ACR (in particular, checking to see that the otherwise default sharpening is set to zero), and the image is then opened in Ps from ACR, and you then choose immediately to close the image without making any edits in Ps, Ps still asks you if you want to save the changes to the document before closing. Why would it do that, given that no edits were carried out in either ACR or Ps itself? By way of contrast, if you open an image in Ps from Bridge and then immediately close it without making any adjustments, Ps does not ask the question. This seems inconsistent.
            • 3. Re: ACR 4.4.1 opening 8-bit TIFFs as 16-bit TIFFs
              Ramón G Castañeda Level 4
              Andrew,

              You are severely confused.
              >Seems like ACR should be able to tell the bit depth of a file

              RAW files are neither 8-bit nor 16-bit by themselves. It is the conversion in ACR that produces a non-raw (cooked) file in whatever bit depth you define in ACR.

              >and the image is then opened in Ps from ACR, and you then choose immediately to close the image without making any edits in Ps, Ps still asks you if you want to save the changes to the document be

              The instant you click on Open in the ACR dialog box, a brand new image is created in RAM with whatever parameters you define in ACR. You no longer are looking at your raw image {or TIFF] but at a converted image that exists only in RAM. If you do not save it, that image is lost forever --meaning that you need to go back and open the raw image {or TIFF] in ACR all over again.

              You need to do your homework, Andrew. Read the white papers linked in the FAQs of this forum to understand what a raw image is (essentially a very, very dark linear grayscale image) and read Jeff Schewe's book on ACR to learn how to use it.
              • 4. Re: ACR 4.4.1 opening 8-bit TIFFs as 16-bit TIFFs
                Ramón G Castañeda Level 4
                Listen, I know you're dealing with TIFFs, but when you open them in Adobe Camera Raw, ACR treats them as if they were the result from RAW-to-non-linear conversion.
                • 5. Re: ACR 4.4.1 opening 8-bit TIFFs as 16-bit TIFFs
                  Level 1
                  Ramon,
                  Thanks. I'm pretty comfortable about the way ACR handles RAW files and what a RAW file is, including the fact that it does not have a bit-depth until cooked. I also now grasp, from your explanation, the fact that when you open either RAW or TIFF (or JPEG) from ACR into Ps you are creating a new image in RAM - thus the need to save it out. I just had not thought that through - no confusion really, but merely a case of the brain being switched off, temporarily I hope :)