Split image of any size into to 4 quarters

Question

I am trying to create a script that splits any input image into 4 different parts (2x2).

I tried the following:

convert "$1" -crop 50%x50% +repage output%d.jpg

With some input images it generates the following files as expected and they are correctly split:

output0.jpg
output1.jpg
output2.jpg
output3.jpg

However with some other input images it only creates 3 output files. It actually never creates the the 4th quarter.

Could this be a bug or should I use another way for achieving this?

Answer 1

I'm not sure why the command gives those results, but a "-gravity" setting could affect a crop operation like that. Also the input image page geometry could make the operation act in ways that might not be expected

If I want to crop an image into quarters I would use a command like this...

magick input.png -crop 2x2@ result%02d.png

The "@" flag tells the operation to crop into 2 columns and 2 rows as equally as possible.

If you provide a sample of one of the images that causes the problem we can see if there might be better answers.