Hello, does anyone know good methods to recover pure state of scanned/photographed document pages with colors.
Goals:
Remove grain/noise
Gray/yellow background convert to white
Keep colors of stamps and details of text
Optionally fix perspective
My method:
1. Optional correction of perspective using Mesh Warp Tool and setting on source points to the corners of page and straightening curves.
2. Use Flood Selection Tool with ~20-25% tolerance not contigous on background and after that delete key, but the problem is i'm loosing too much details and text become too gray/invisible.
3. Use Inpainting Tool to remove separated noise/dust/scratches.
4. Use Undo Brush Tool on color stamps,text,graphics to recover it's colors saturation.
5. Use Erase Brush Tool on that color stamps recovered in 4th point to remove gray/yellow borders. Maybe there is better method to select for example all gray channel and remove it but without loosing details from text?
Maybe someone knows faster and more accurate method than mine - using channels, levels, colors selection, etc. ?
I remember that in Gimp there was something like Threshold - but there was problem with colors also.
I provide few samples below.