Hello. I knew how to create coffee stain, there are too many tutorials available for that but google always tell me what I knew. In fact I don't need gimp to make coffee stain, I can simply pour coffee on the print output. What I need is to remove coffee stain from a scanned document.

In my case I think it should be easy because the document is printed in blue color while coffee stain dark and red. A person can easily tell documents from the stain, so should gimp. Can you recommend a tutorial that I can follow, that solves similar problem?

Thanks Zhang Weiwu

Zhang Weiwu wrote:

Hello. I knew how to create coffee stain, there are too many tutorials available for that but google always tell me what I knew. In fact I don't need gimp to make coffee stain, I can simply pour coffee on the print output. What I need is to remove coffee stain from a scanned document.

In my case I think it should be easy because the document is printed in blue color while coffee stain dark and red. A person can easily tell documents from the stain, so should gimp. Can you recommend a tutorial that I can follow, that solves similar problem?

I found the solution now and can answer to my own question.

Use "Colors -> Components" to separate the scan to CMYK, remove all except cyan (so we removed the coffee stain and kept the blue ink), do color replacement to get the cyan back to blue. Done.