Re: [gentoo-user] faded images with Gwenview

[Michael]

On Thursday, 9 September 2021 00:25:41 BST Philip Webb wrote:
> I have cropped some  .png  images using Gwenview
> & the reduced versions are faded with Gwenview, but fully colored with Feh.
> I've tried using 'convert' to create  .jpg  versions,
> but while they're much smaller in Kbytes (good),
> they're also faded when viewed with Gwenview (Feh ok).
>
> Can anyone explain what has caused this ?
> Is there a way of correcting it, eg with Imagemagick ?

Once you have converted an original raster image into a smaller (i.e. more 
compressed) jpeg image you have thrown away some pixels.  Post-processing 
can't put these missing pixels back.

I think the gwenview faded display phenomenon you describe here is unlikely to 
be the result of your conversion, since feh displays it without any fading.  
It may be caused by gwenview scaling the image to a different size, to make it 
fit in the gwenview window, unlike feh which will open it in its original size 
whether its full size dimensions fit in your PC monitor or not.  You can check 
the gwenview % reduction/increase shown at the bottom right hand corner and 
change this to 100% to see if it makes any odds.

In the gwenview settings you can select what the default 'Zoom Mode' is, if 
indeed this is the cause of the faded image display.

Another thing perhaps related could be the anti-aliasing gwenview applies to 
fit the image in the window aperture and how this interacts with the image 
elements and the resolution of your monitor - you should be able to check this 
if you change the zoom level.

https://photo.stackexchange.com/questions/24512/what-is-aliasing-and-anti-aliasing

On the same PC/monitor with the same display dimensions for an image gwenview 
(with its default settings) and feh ought to produce the same output - at 
least they do so here.