Exporting as PNG includes all the JPEG artifacts

[Mel B.]

Version: Shutter 0.93.1 Rev.1278
Linux: Arch

Reproduce a bug:

1) Take a screenshot of some text on a webpage (for example)
2) Select "Save As"
3) Select PNG from drop-down Image Format menu
4) Open the newly saved PNG file, zoom in in your favorite viewer, and observe all the JPEG artifacts.

I believe this is due to Shutter saving its internal/intermediate image files as JPEGs. If you change, in preferences, default format to something that's not lossy, you will be able to save pixel-perfect PNG files.

Recommendation for a bug fix: even if the preferred file format for saving files is JPEG, don't store intermediate representations as JPEG files. Export JPEG from a non-lossy file format instead. That's probably what the user wants anyway.

Thank you.