Cropped images are sometimes 1 pixel too small

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smartcrop --width 100 --height 400 %1 %~n1_out%~x1

When I run this command on kitty.jpg from the test suite, the output image is 99x400.

I assume this happens because of the skewed aspect ratio of the requested crop, I've encountered a similar "missing pixel" problem when cropping in Photoshop. Is there a way to force exact dimensions for the output?