ebook-viewer: Transparent PNG renders strangely in dark mode viewer

[ownedbycats]

See screenshot. Will attach the exported image in a comment.

[ownedbycats (ownedbycats)]

One of the semi-transparent PNGs in this ePub.

[ownedbycats (ownedbycats)]

(Also, disregard my desktop wallpaper. I thought it was funny.)

[Kovid Goyal (kovid)]

Nothing can be done about that. That PNG image is designed to render
against a light background. There is no reasonable way for the viewer to
know that.

 status wontfix

[ownedbycats (ownedbycats)]

I find it a bit odd that even though the image frame is grey, the transparency still shows as black. Is that some limitation of Qt?

[Kovid Goyal (kovid)]

its not Qt, put the image in a html file with black background and view
it in a browser.

[ownedbycats (ownedbycats)]

I'm talking about the light grey part surrounding the image. Why does the transparency turn black instead of light grey?

[Kovid Goyal (kovid)]

Oh you mean in the view image popup, i thought you meant in the viewer itself.

[Kovid Goyal (kovid)]

It will be because Qt has to pick some color to use when rendering the transparent pixels in the image. It presumably chooses the default background color, which is white in light mode and black in dark mode The image viewer does not blend the image with gray, the gray is there to improve color perception in the image by surrounding it with a neutral color.

[Kovid Goyal (kovid)]

Fixed in branch master. The fix will be in the next release. calibre is usually released every alternate Friday.

 status fixreleased