Problem with graphics in Qt embedded Linux

[Krzysztow]

Anyway, thank You for Your ideas.

The update itself is quite costly, so it may be done only if the problem is solved.

Images that are drawn are PNGs and lately we also tried to convert them to BMPs. It helped but not completely, there is a smaller amount of these bunches of bad pixels.

[wysota]

This further suggests the issues are colour-related. Once you start drawing, it doesn't matter what the original file format of the image was. Try creating images with different gradients and try to spot if the artifacts are consistant with the direction of the gradient. Create the gradient images directly in your application - don't load them from files.