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Image diff comparison doesn't indicate mismatch for pixels that don't exist

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  • Image diff comparison doesn't indicate mismatch for pixels that don't exist

    I didn't see this posted already, if it's there, sorry for the duplicate.

    I have two images, one has an extra border around it. The comparison window shows black for all matching pixels, (it'd be red if it was different)

    However, black is also shown for the border area that doesn't exist in both images. It seems like this border area should be red indicating a mismatch between "something and nothing"

    If I show "info" it indicates with a thin red underline that they're different in size, but at a quick glance in the middle diff pane they appear to be the same, which is misleading. (See attachment)

    Question: How do I get BC to show the unmatched pixels as red differences in the comparison pane.
    My settings are a tolerance of 25 and I believe all defaults, nothing special. If I allow them to be scaled, many pixels are different.

    Thank you.
    Attached Files

  • #2
    Thanks for the post. In this case, the difference pane in the center shows difference coloring in areas of overlap. If dragged around or out, the original coloring is restored. This helps in scenarios where different sized or cropped images need to be aligned. In the specific case of having a black image border, it can be a bit confusing in Range mode, which also uses a black coloring for equal.. If you look at the bottom status bar that shows the overall comparison status, it is marked as Important Differences, correct? Also, if you switch to Tolerance mode, the overlay should be greyscale for the equal section, and black for the border, which may help it stand out more.
    Aaron P Scooter Software


    • #3
      Hi Aaron, thanks for the reply.

      Yes, the lower left indicates "Important differences". I did find the picture compare option and set the tolerance mode to gray scale; that helps show the difference a bit more, but now things matching show up in the center diff pane so it's not what I was hoping for. If I change the "same pixels" color setting to a different color (say green), I get more of what I'm looking for. (Everything is green except for the mismatched boarder, which is black.
      With that said, it still seems sensible to have the center difference pane to show all red for unmatched pixels as well as missing pixels.

      Since the options have settings for same pixels, different pixels, and similar pixels, perhaps the improvement I'd suggest is to add options for "missing" pixels and default that color to red, just like the different pixel color.

      With your suggestion I have a work-around - if you can pass that along my suggestion to the development team, I'd appreciate it. I'm a long term user of BC and it's definitely one of my top ten utilities.



      • #4
        Sure it's definitely something we can consider and I'll pass that along. To understand our current behavior, please consider this scenario: the comparison pane allows reposition and zoom controls. As you drag the two pictures, you can drag them completely off of each other, resize one to match the other, or move them around. If orphan/missing pixels are marked as a stark or transparent red, then as the photos are positioned it would be very difficult to read. The center would be the offset/different pixels you are trying to position (mostly different during the positioning) while the outside would be a entirely different. The comparison pane itself is a tool to control the comparison, while the status bar is the overall result. Of course, if we can design the comparison pane to easily relay a more complete picture ( ), that would overall improve the user experience.
        Aaron P Scooter Software