On Mon, 1 Mar 2021 11:50:35 +0000, Wols Lists wrote: > I've got a bunch of scans, let's assume they're text documents. And > they're rather big ... I want to email them. > > How on earth do I convert them to TRUE b&w documents? At the moment they > are jpegs that weigh in at 3MB, and I guess they're using about 5 bytes > to store all the colour, luminance, whatever, per pixel. But actually, > there's only ONE BIT of information there - whether that pixel is black > or white. > > I'm using imagemagick, but so far all my attempts to strip out the > surplus information have resulted in INcreasing the file size ??? > > So basically, how do I save an image as "one bit per pixel" like you'd > think you'd send to a B&W printer?
$ convert input.jpg -threshold 50% output.png should do it, you may need to play with the threshold setting. The file command reports the output file as being "1-bit grayscale". You can also use -monochrome but that will produce a dithered image, that's probably not what you want judging by your description. -- Neil Bothwick If we aren't supposed to eat animals, why are they made of meat?
pgp3M42KfH1ou.pgp
Description: OpenPGP digital signature
