Repair Scanned Images Using ImageMagick

scan-magick.md

Improve/Repair Scanned Images Using ImageMagick

This is the command:

magick "img-01.tiff" -strip -kuwahara "1.5" -modulate "100,90" -level "6,92%,0.75" -quality 80 "img-01.jpg"

• -strip - remove any metadata
• -kuwahara "1.5" - apply smoothing algorithm
• -modulate "100,90" - reduce saturation a bit
• -level "6,92%,0.75" - improve contrast and decrease gamma (whitens background and makes image darker)

This is the effect:

Get full version of the image.

Convert every file in a directory using PowerShell:

Get-ChildItem *.tiff -File | ForEach-Object -Process {
    $i = $_.Name; $o = $_.BaseName + ".jpg";
    magick "$i" -strip -kuwahara "1.5" -modulate "100,90" -level "5,92%,0.74" -quality 80 "$o"
}

Imagemagick filters that smooth & reduce noise

• -despeckle - Reduce the speckles within an image.
• -enhance - Apply a digital filter to enhance a noisy image.
• -statistic median geometry - Select the "middle" value from all the surrounding pixels.
• -statistic nonpeak geometry - Reduce noise in an image.
• -adaptive-blur radius[xsigma] - Adaptively blur pixels, with decreasing effect near edges.
• -kuwahara radius[xsigma] - Edge preserving noise reduction filter.
• -bilateral-blur width - A non-linear, edge-preserving, and noise-reducing smoothing filter.