XnView Software

Transparent pixels dont get filtered correctly if adjanced to none transparent pixels.

Attached I have a picture of a white circle with red background (background 100% transparent).
If you view this at 100% you correctly get a white circle.
If you view it scaled to less than 100% the circle edges start bleeding red, which is wrong.

This is because the filter doesnt weigh pixels by their transparency-value, so a red pixel with 100% transparency and a white pixel with no transparency become a light red pixel with 50% transparency instead of a white pixel with 50% transparency.

ADDENDUM:
- for viewing pictures the bug only happens with high quality zoom enabled
- for resizing an image the bug always happens (not with nearest pixel mode)

Confirmed for activated High quality zoom (Tools » Options... » View » View).

It seems the bug even happens when you resize the image via resize-function, no matter which filter.
And here even disabling high quality zoom doesnt help.

Added it to the main-post.

3murmeln wrote:It seems the bug even happens when you resize the image via resize-function, no matter which filter.

See also: Reducing Halo Effect in Rescaled/Resized Images

XnView v2.40 (top) vs. v2.39 (bottom):
Remaining issues:

1. In view mode, zooming in still produces a “halo” if Tools → Options... → View → View → High quality zoom → Enlarge is activated.
2. High-quality zoom doesn't work in the preview pane.

PS: I haven't done any tests for fullscreen and fullscreen lite yet.