How can I convert a JPEG photo to black and white (not grayscale) image like output of a FAX scanner, by ImageMagick?
ImageMagick – How to Convert a Photo to Black and White Image
imagemagickimagesjpeglinux
Related Solutions
-monochrome
This option uses some smart dithering and generates very visible output:
convert -monochrome in.png out.png
Documentation: http://www.imagemagick.org/Usage/quantize/#monochrome
Compare that to a simpler -threshold 50 transform:
convert -threshold 50 in.png out.png
which loses most of the image.
Concrete example from: https://www.nasa.gov/mission_pages/galex/pia15416.html
wget -O orig.jpg http://www.nasa.gov/images/content/650137main_pia15416b-43_full.jpg
# Downsize to 400 height to have a reasonable file size for upload here.
convert orig.jpg -resize x400 in.jpg
convert -monochrome in.jpg out.jpg
convert -threshold 50 in.jpg threshold-50.jpg
in.jpg
out.jpg
threshold-50.jpg
Related questions:
- https://stackoverflow.com/questions/15861025/how-to-convert-an-image-to-1bit-px-binary-bitmap-with-imagemagick-or-rmagick
- https://askubuntu.com/questions/9868/convert-an-image-from-grayscale-to-binary
- https://unix.stackexchange.com/questions/108613/how-do-you-binarize-a-colored-image
Tested in Ubuntu 19.10, ImageMagick 6.9.10.
Updated: This should work (-flatten did the trick for me)
convert -geometry 110% your.eps -flatten your.jpg
Best Answer
According to this forum post:
However, if you want two colors only (black and white), then you need to threshold. For example, to select the color where above will be white and below will be black.
where xx is in range 0-100 (for percent).