[gentoo-user] [OT] Saving an image as black and white

[Wols Lists]

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?

Even at 300dpi, I make that 300*300/8 ~= 10KB/in^2 or 800KB of
uncompressed info for a page of A4, not 3MB.

Cheers,
Wol