Threshold grey images to black or white?
by grumpyskeptic from LinuxQuestions.org on (#5Q8QJ)
My scanner outputs pdfs of scans of pages of text as black lettering on a dark grey background.
Is there any GUI software available that can quickly and easily threshold the black to black and the grey to white? If this cannot be done with pdfs, I could convert the pdfs to jpgs.
The last time I did this it was a multi-stage process that took all afternoon.
Thanks.
Appendix:
My scanner has these bugs which prevent adjusting the contrast and brightness:
https://bugs.launchpad.net/ubuntu/+s...n/+bug/1327801
https://bugs.launchpad.net/ubuntu/+s...s/+bug/1868408
I have tried several different scanner programs, and they all have the same problem apart from Xsane which gives poor results. The manufacturer does not supply Linux drivers for my scanner model any more.
Is there any GUI software available that can quickly and easily threshold the black to black and the grey to white? If this cannot be done with pdfs, I could convert the pdfs to jpgs.
The last time I did this it was a multi-stage process that took all afternoon.
Thanks.
Appendix:
My scanner has these bugs which prevent adjusting the contrast and brightness:
https://bugs.launchpad.net/ubuntu/+s...n/+bug/1327801
https://bugs.launchpad.net/ubuntu/+s...s/+bug/1868408
I have tried several different scanner programs, and they all have the same problem apart from Xsane which gives poor results. The manufacturer does not supply Linux drivers for my scanner model any more.