No announcement yet.

Picture Compare in BC3 without Transparency?

  • Filter
  • Time
  • Show
Clear All
new posts

  • Picture Compare in BC3 without Transparency?

    I just upgraded to BC3 from BC2, and am having a problem with the new transparency feature in the Picture Compare viewer. In particular, I want to turn it off and only compare the RGB channels of my transparent PNG files. Is there a way to do this? I was unable to find anything relevant in the options dialog.

    The images I am comparing are framebuffer dumps from programs testing 3D graphics APIs. The alpha channel of the image files is taken directly from the alpha channel of the framebuffer, which is not necessarily or even typically used for transparency. When scanning out to a monitor, graphics hardware typically ignores the contents of the alpha channel of the framebuffer.

    I do have other tools whose picture comparison features are better suited for my purposes; perhaps that's the best solution for this scenario. However, I did use BC2 for these purposes because the directory compare capabilities were better than those in my other tools, and the picture compare tool (without transparency support) behaved as I wanted. The only thing I missed there was the ability to compare alpha channels.

    Let me know if you have any suggestions.

  • #2
    Thanks for the suggestion. I've added some notes to our Customer Wishlist.

    We currently show the alpha channel on either side, but it is not compared, and should not change the comparison status of the center pane when compared to BC2. Are you seeing different behavior?
    Aaron P Scooter Software


    • #3
      Sorry I didn't follow up sooner -- just busy and forgot to follow up on my original question. The center pane on BC3 does look similar to BC2, as you expect.

      My issue with the regular image panes, which I used in BC2 to eyeball differences. A simple example of the sort of image I'm comparing -- the image has some objects drawn in the foreground with an alpha of 0xFF on top of a background with an alpha of 0x00 and an RGB color of 0x008000. Since alpha isn't transparency for the purposes of this test, I'm expecting to see a green background. Instead, I'm getting a checkerboard.

      My workaround is to either (a) use BC2 or (b) use a home-grown image comparison app more specifically designed for this sort of application.

      BTW, one other piece of picture compare feedback while I'm thinking about it... The other image compare applications I use have a quadrant-based layout instead of BC2/BC3's side-by-side-by-side layout. The two images are displayed in the upper left and right, the diff window is in the lower right, and miscellaneous GUI controls can be found in the lower left. In this layout, the aspect ratios of the windows are more closely aligned with those of "normal" images. In BC2/BC3's layout, each image pane is tall and skinny. 4x3, 16x10, or 16x9 aspect ratio images don't fit very nicely in panes with aspect ratios like 1x2.


      • #4
        I would be interested in seeing a screenshot of the other image compare tool with the quadrant-based layout...
        BC v4.0.7 build 19761


        • #5
          Thanks for the feedback. I'll add these notes to the entry.

          Along with Michael, I would also appreciate information on the 4 squares, or quadrant, view.
          Aaron P Scooter Software