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Rachael286353566w9z
Participant
August 1, 2025
Answered

inconsistent 10% SFR Image Degradation post process stitching TIF files in PS '24

  • August 1, 2025
  • 2 replies
  • 258 views

Issue: Cultural Heritage Digitization - TIFFs stitching introducing image quality issues in 10% SFR

  • Photoshop version: 25.9.1
  • OS: Sequoia 15.4.1


Steps to reproduce:

  1. ... Open 2 TIFF files in PS
  2. ... Move to same canvas
  3. ... Align layers manually using free transform
  4. .. Make selections (path, lasso, brush), create mask and refine mask to stitch or mosaic TIFFs into one TIFF
  5. ... Flatten layers and safe TIFF
  6. ... Originating TIFF files contain image targets that test well , final file targets are hit or miss

 

Expected result: Files used to stitch and stitched files should have the same image quality
Actual result: Processed files in Photoshop sometimes show degradation in image quality, specifically in the 10% SFR measurements, this is visually aparent and measurable via tools like Open DICE. This image quality degredation has not been consistently reproducable. 

 

Has anyone else encountered this? Our workaround has been to restitch files, which usually fixes the problem. I wondered if it was due to leaving files open too long and coming back to them while multi-tasking, but recently we reproduced the error when we attempted to redo our work, so that workaround is not reliable. So far we've tried different saving settings and different selection methods and refinement methods for the masks that do not seem to improve results. We have not tested this with automated photomerge yet.

 

 

 

    Correct answer Stephen Marsh
    quote

    Free transform allows us to rotate precisely the layers to align the files


    By @Rachael286353566w9z

     

    Rotation requires interpolation/resampling, just as resizing or skewing or other transforms do.

    2 replies

    R
    Rachael286353566w9zAuthor
    Participant
    August 1, 2025

    Thank you for the quick reply! That makes sense -- we are using free transform to rotate the canvas quickly and have not been using free transform for resizing making it bigger or smaller. Free transform allows us to rotate precisely the layers to align the files as there is some movment of the materials when we shift them on our copystand due to limited space -- is there another tool you recommend us to try? Thanks again!

    E
    ExUSA
    Legend
    August 1, 2025

    Are you using medium format digital? A Phase One is probably the best for this kind of work but its $$$.

     

    If you have to move things, you need a bigger space. There are also large format scanning backs if one of those would be a fit for you.

     

    Talk to this outfit, they specialize in your field. https://www.captureintegration.com/

    R
    Rachael286353566w9zAuthor
    Participant
    August 1, 2025

    Thanks for the recommendation and yes, We're using 150mp Phase One cameras and unfortunately we are limited on space and aim to resolve at or near 400PPI to reformat these oversized maps, so we need to mosiac or stitch the files in any case, but we do have a very solid support for readjusting items and a well controlled environment for producing FADGI 4 star quality.  

     

    We've been stumped on why the issues in 10% SFR appear only sometimes when stitching our files in PS. I think the idea that free transform is changing the image quality would make a lot of sense if only one of our targets was testing poorly regularly, as we're only applying free transform adjustments to rotate one layer in our compositing process, but the image degredation is usually popping up for both targets, the bottom and the top layer of these 2 part stitches. We haven't yet tested to see if the automated photomerge is producing similar results, as these materials weren't playing well with that feature, but wonder as that readjusts files as well if there are similar results.

    E
    ExUSA
    Legend
    August 1, 2025

    Using free transform will alter the original pixels, that's the whole point. Are you using a rig that moves either the camera or original laterally so there is no distortion? If this is done properly, there should be no need to transform anything. You should just be able to use a large canvas and the move tool to align image tiles

     

    A file will not change from being left open.

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