If you mean that you jpeg got a black background.

This has to do with the transparency of the uploaded image. What was transparent in the original image will become black in the saved file on your Elgg website. This is because we convert the file to a jpeg an jpeg doesn't support transparency. The system will fill that in with black.

If you don't want that, don't upload an image with transparency. Maybe if you edit the image before you upload it and make the transparency the color you like this will fix the issue.

i mean about my file jpg when i open is good color, when i upload this file to my EGG theme on backgroud topbar is more darkned like change visible. if you know what i mean please help, maybe problem is in code plugin

@Wojtutto 

The plugin's code is ok.

JPG/JPEG does not support transparency.

If the original image has a transparent background (e.g., PNG) and Elgg save it as JPG, the transparent areas will automatically be replaced with black.

If you need a transparent background, use the PNG format.

no. the same file is there: https://qolormah.pl/serve-file/e0/l1763499167/di/c0/YbNxIRPY2TZY2NFDIc6CdzDyKsTbZjzgP25CclDjrHw/1/70/icons/icon/xlarge.webp

and  there

qolormah.pl

no. the same file is there: https://qolormah.pl/serve-file/e0/l1763499167/di/c0/YbNxIRPY2TZY2NFDIc6CdzDyKsTbZjzgP25CclDjrHw/1/70/icons/icon/xlarge.webp

and  there

qolormah.pl

If you inspect the image on your website you can see that it gets the class 'elgg-featured-cover' which has a black background  with a transparency. that's causing the image to appear darker.

i dont know where i must change it

Edit this on:

background-color: transparent;

Don't forget run 'Upgrade' via admin panel to clean the caches

ok very thanks