In a color managed workflow, when a PNG file has alpha channel, Gwenview renders the picture's color incorrectly. On a standard gamut sRGB display the differences might be hard to see, but on a wide-gamut display, the color shift is difficult to overlook. In the same environment, Gwenview displays PNG without alpha channel and JPGs with proper color management. I will attach test images I used later. The definition of a "color managed workflow" here: 1) the display has been calibrated and profiled 2) the display's ICC profile (product of step 1) has been assigned properly in colord-kde 3) Krita, Firefox, Chromium are all doing color management correctly. 4) the picture was exported by Krita with "Embed sRGB profile" option checked.
https://www.dropbox.com/s/541v16df3a20vwj/electrichearts_20190929A_Skye_a.png?dl=0 This is a test PNG image with alpha channel. When opened by Gwenview on a wide-gamut display, the goose's beak looks over-saturated. https://www.dropbox.com/s/541v16df3a20vwj/electrichearts_20190929A_Skye_a.png?dl=0 This is the same picture without alpha channel. When opened by Gwenview on a wide-gamut display, it looks the same as on a standard gamut display.
https://www.dropbox.com/s/lcemt5w1f2f8d7y/electrichearts_20190929A_Skye_b.png?dl=0 Sorry, this is the one without alpha channel. I copied the wrong URL.
Thank you for the bug report. Unfortunately we were not able to get to it yet. Can we ask you to please check if this is still an issue with Gwenview 25.08.0 (the latest released version)?
I think it has been fixed.