Removing unwanted color, make just b & w

[carljong]

Attached is an admittedly bad scan of sheet music.  It is not being recognized by my piano notation software.

I'm familiar with Colors > Curves to clean up sheet music, but it is not working on this photo.

I saw Despeckle, but the only effect it seems to have is to make things worse.

I wish I could just capture a sample of the bad section, say "this is the pattern", and get rid of it.

Thanks

[rich2005]

The 'noise' is much the same size as some of the notation, I do think it will ever be wonderful.

A reasonable result of your example using Filters -> Enhance -> Noise Reduction and a bit of smoothing with Filters -> Blur -> Median Blur with radius = 1

   

[Kevin]

The problem is the noise in your image is all black, so curves won't work.

I did the Nose Reduction as per rich2005, and as that's made the noise into grey then used a curves adjustment to loose the noise:

   

[denzjos]

Another workflow :
- G'Mic-Qt / Black&White / Stamp (just move the 'Smooth' slider to the right until the dots disappear,value 1.26)
- G'Mic-Qt / Repair / Smooth (NL-Means) 
   
- Optimise with gimp 'Filters / Enhance /Sharpen (Unsharp Mask)'
   

[sallyanne]

Try G'MIC's repair scanned document (under repair) - doesn't get rid of all the black dots but does most

[attachment=8943]

[rich2005]

@denzjos @sallyanne

the gimp-gmic-qt plugin is a great tool for this.

However the OP is using MacOS and therefore unlikely to have gmic

[denzjos]

(10-31-2022, 02:09 PM)rich2005 Wrote: @denzjos @sallyanne

the gimp-gmic-qt plugin is a great tool for this.

However the OP is using MacOS and therefore unlikely to have gmic

Okay, I'll keep it in mind.