How can I convert an image to grayscale via the command line?

linux image command-line sips
cwd picture cwd · Oct 10, 2011 · Viewed 55.4k times · Source

How can I use sips, imagemagic, or another tool to convert an image to black and white (grayscale) via the command line?

Answer

mark picture mark · Oct 10, 2011

If you have imagemagick installed, 

convert source.jpg -colorspace Gray destination.jpg (true grayscale only)
convert source.jpg -monochrome destination.jpg (true black and white)
convert source.jpg -separate destination.jpg (separate into gray channels)

If you don't care about losing the original file: mogrify -colorspace Gray file.

Related questions

How to base64 encode image in linux bash / shell

I'm trying to base64 encode an image in a shell script and put it into variable: test="$(printf DSC_0251.JPG | base64)" echo $test RFNDXzAyNTEuSlBH I've also tried something like this: test=\`echo -ne DSC_0251.JPG | base64\` but still with no …

Read More
Fast way to get image dimensions (not filesize)

I'm looking for a fast way to get the height and width of an image in pixels. It should handle at least JPG, PNG and TIFF, but the more the better. I emphasize fast because my images are quite big (…

Read More
How to create an .IMG image of a disc (sd card) without including free space?

In Linux, we can do dd if=/dev/sdb of=bckup.img but if the disk is of 32GB with only 4GB used, the 32GB image file is waste of space-time. Is there any way or tool to create images …

Read More