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

2021-03-04 Thread Frank Steinmetzger
Am Mon, Mar 01, 2021 at 03:54:12PM + schrieb Wols Lists: > >> 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 set

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

2021-03-01 Thread Rich Freeman
On Mon, Mar 1, 2021 at 10:54 AM Wols Lists wrote: > > And the png does make a massive difference - the same command with jpg > output is 1.7MB - so why is my scanner chucking out 800KB jpegs if I set > it correctly? jpeg quality is adjustable. You can output a jpeg file of almost any size. Soft

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

2021-03-01 Thread Wols Lists
On 01/03/21 13:48, Neil Bothwick wrote: > On Mon, 1 Mar 2021 11:50:35 +, 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 >>

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

2021-03-01 Thread Rich Freeman
On Mon, Mar 1, 2021 at 8:48 AM Neil Bothwick wrote: > > 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

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

2021-03-01 Thread Neil Bothwick
On Mon, 1 Mar 2021 11:50:35 +, 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: [gentoo-user] [OT] Saving an image as black and white

2021-03-01 Thread Hund
On March 1, 2021 12:50:35 PM GMT+01:00, 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 the

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

2021-03-01 Thread 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, what