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Am Mon, Mar 01, 2021 at 03:54:12PM +0000 schrieb Wols Lists: |
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> >> So basically, how do I save an image as "one bit per pixel" like you'd |
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> >> think you'd send to a B&W printer? |
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> > |
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> > $ convert input.jpg -threshold 50% output.png |
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> > |
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> > should do it, you may need to play with the threshold setting. The file |
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> > command reports the output file as being "1-bit grayscale". |
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> > |
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> > You can also use -monochrome but that will produce a dithered image, |
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> > that's probably not what you want judging by your description. |
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> > |
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> > |
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> FINALLY! |
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> |
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> Thanks, that worked! Okay, I also adjusted the dpi because the original |
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> scan was 600 and I've reduced it to 300, but this has reduced the file |
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> size from 3MB to 180KB. |
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Also note: DPI is just a factor that is stored in the image’s metadata. What |
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produces the actual filesize are the pixels. DPI is used to “convert” |
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between the physical size of a hypothetical print (i.e. sheet of paper) and |
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the number of pixel required for a certain density (and thus, quality). |
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As far as I know, jpeg does not have a special “grayscale mode”. You may |
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have reduced the information of the image by making all three colour |
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channels equal to one another, but jpeg still encodes the data as if were a |
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colour image. That’s why png is the much better option in this case. |
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-- |
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Gruß | Greetings | Qapla’ |
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Please do not share anything from, with or about me on any social network. |
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UNIX is not user-unfriendly. |
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It just expects the user to be a little more computer-friendly. |
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