Strangeness with individual color channel views

[Unordinal]

Windows OS version

Windows 11 Pro 24H2

ImageGlass version

9.3.2.520

ImageGlass release

Classic

1️⃣ Steps to reproduce

1. Open an image with an alpha channel (tested with .dds, .png, and with at least 3 other images)
2. Shift+C to bring up the 'View channels' dialog
3. Click RGBA. You may need to repeat 2 and 3 to see a visible difference.
4. After doing 3 and seeing a difference, try viewing just 'R/G/B + A'; there's still colors 'left over' from the RGBA mode, and clicking these other channels a few times also seems to cause different results.
5. Clicking to RGB and then back to RGBA a few times will show the 'bleed over' of the black portions in the RGBA where there should be transparency.

2️⃣ Actual behavior

The color channels appear to be layering on top of each other in some way, and are otherwise changing each time you try and view a specific color channel, almost like bleed over from the previously-selected channels. I'm unsure exactly what is happening, but it's an incorrect result.

3️⃣ Expected behavior

To see the color channel I selected properly and how it should appear; i.e. 'R + A' should display just the red channel in grayscale along with transparent portions.

4️⃣ Screenshots / Video / Sample image file

Clip showing the problem: https://github.com/user-attachments/assets/ab0000c8-d480-484e-bf73-cd5a901cb122

5️⃣ Additional context

May be a problem with the alpha channel layering? I haven't tried extensively, but images without alpha seem like they don't have this problem. (Again, only tested a tiny bit with other images.)

[d2phap]

I could not reproduce on my end. Can you try disabling the transparency (set Window backdrop to None in Settings > Appearance)?

[Unordinal]

Issue still occurs, even after a restart of ImageGlass after changing the setting.

[d2phap]

Thank you. One more, can you try changing the background to white or any other non-transparent colors

[Unordinal]

Unfortunately, didn't help. I've also tried with async image loading enabled/disabled, image preview while loading enabled/disabled, setting image booster cache to 0, and resetting my settings to default, just in case any of that was causing the problem, and no luck.

[d2phap]

@Unordinal Thank you! At the moment I cannot reproduce this, I will just keep this issue open.

[Unordinal]

After some debugging, it appears to be a problem with pixels in the transparent areas not being cleared properly? Forcing ignoreAlpha in ViewerCanvas.FilterColorChannels to true fixes the issue, though obviously displays images with alpha incorrectly. Going farther, in ID2D1EffectExtensions.GetD2D1Bitmap1, doing a dc.Clear() immediately after the dc.BeginDraw() call fixes the issue, seemingly without any other issues occurring.

I have zero experience with Direct2D however, so I'm not sure if this has any unintended consequences, nor why this issue seems to be only on my end.