XnView 2.43 shows dots under certain conditions

[dma_k]

Dear XnView team,

I have noticed that when displaying certain TIFF files, XnView renders such dots:

screenshot.png

Steps to reproduce:

• Download attached TIFF file.
• Expand XnView to whole screen.
• Open the image, choose "Fit image to window height" (or press NumPad3).

Observations:

• When XnView is not expanded to whole screen, I was not able to reproduce the problem (dots are gone).
• When I zoom in/out the image, the dots are gone.
• When change the canvas height from 1559 to 1560, the dots are gone.
• I have found only few TIFF images that cause such an effect. They all have different density of dots.

I have a feeling the problem has something to do with image/screen/viewport ratio.

Buggy (affected) XnView versions: 2.41, 2.42, 2.43, 2.44
Not buggy XnView versions: 2.35, 2.38, 2.40

[xnview]

right i can reproduce...

[dma_k]

I don't know if that is related, but I see dots on white background on thumbnails. XnView v2.48.

xnview_dots.png