How to split an image vertically using the command line?

Question

Say I have a large 800x5000 image; how would I split that into 5 separate images with dimensions 800x1000 using the command line?

Solution 1

Solved it using ImageMagick's convert -crop geometry +repage:

convert -crop 100%x20% +repage image.png image.png

Solution 2

Using ImageMagick:

$ convert -crop 800x1000 image.png cropped_%d.png

Will create a sequence of files named cropped_1.png, cropped_2.png, and so on.

References

• Tile Cropping, sub-dividing one image into multiple images
• ImageMagick v6 Examples -- Cutting and Bordering

Solution 3

Using the "tiles" functionality:

convert image.png -crop 1x5@ out-%d.png

https://www.imagemagick.org/Usage/crop/#crop_tile

Solution 4

ImageMagick would crash on me, for the image being too big for it to handle, so I had to resort to other methods.

I ended up using the Python Image Library.

A quick and dirty answer to the OP question follows:

from PIL import Image

im = Image.open("YourImage.yourformat")

for h in range(0, im.height, 1000):
     nim = im.crop((0, h, im.width-1, min(im.height, h+1000)-1))
     nim.save("PartialImage." + str(h) + ".yourformat")

The above code has the final sizes hardcoded, but it can be easily transformed into an full blow script of its own with all inputs parameterized. If one ever needs such a thing.

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Comments

[slm]

Please don't add the solution to your Q. Mark the answer below as accepted.

[slm]

The OP said that this solved it using convert -crop geometry +repage. For example: convert -crop 100%x20% +repage image.png image.png.

[Admin]

+repage considerations re: image offset capable formats etc.

[JPT]

If you want to apply this to a batch of files, try this: ls -1 *.png | sed 's,.*,& &,' | xargs -n 2 convert -crop 100%x20% +repage

[CMCDragonkai]

How does this compare to @shley's answer?

[Evan Nudd]

@CMCDragonkai it's essentially the same, they're using percentages so it will split any size image into 5 vertical slices instead of being written specifically for the 800x5000 case

[deadfish]

Okay, so 100%x20% splits vertically and 20%x100% splits horizontally.

[cherryblossom]

Newer docs: imagemagick.org/script/command-line-options.php#crop ('You can add the @ to the geometry argument to equally divide the image into the number of tiles generated.')