I opened an image, it appears on the layers screen as a thumbnail, but on the page there is only a black screen. Any advice? I want to adjust the contrast to make it a line drawing.

Strange the next time I opened the image there it was. I pressed the paint over red and blue squares, perhaps that's fixed it.

What you described sounded as an error in the application. If it happens again, please gather as much information as possible about it, and let me know.

I will try it out first. If there are bugs I'll report it to your