djinncoyote ([personal profile] djinncoyote) wrote2016-02-14 02:49 am

using ImageMagick to sharpen multi-page PDF documents

Unlike IrfanView, which requires several steps to sharpen a multi-page PDF, ImageMagick can do it in a single step, using its "convert.exe" command line utility.

I've found that the following parameters give good results for scanned text documents.
They use the "unsharp" parameter, which despite its name is used to sharpen an image.

For 300 dpi scanned documents:

C:\util\ImageMagick-6.9.3-4-portable-Q16-x64\convert.exe -density 300 -unsharp 10x3.2+5.0+0.10 -compress jpeg -quality 75 [input file] [output file]

For 600 dpi scanned documents:

C:\util\ImageMagick-6.9.3-4-portable-Q16-x64\convert.exe -density 600 -unsharp 30x5.5+3.0+0.10 -compress jpeg -quality 75 [input file] [output file]

References:
Sharpening using ImageMagick
ImageMagick command line options