Scanned or photographed image documents are often unsuitable to be used for printing. Archiving them would need too much space on your harddisk. With the following command, which uses ImageMagick, the document is being converted into a black/white image document.

The command is from lelandbatey and is originally used for digitalising „white boards“, see here.

improvetextdoc.desktop

[Desktop Entry]
ServiceTypes=KonqPopupMenu/Plugin,image/*
Type=Service
Actions=improvetextdoc;
X-KDE-ServiceTypes=KonqPopupMenu/Plugin
MimeType=application/octet-stream;
X-KDE-Submenu=Archive
 
[Desktop Action improvetextdoc]
Name=Improve document
Icon=
Exec=convert "%U" -morphology Convolve DoG:15,100,0 -negate -normalize -blur 0x1 -channel RBG -level 60%,91%,0.1 "%U.png"