I want to cut 30% from the top of the image.
I know the thread How to cut a really large raster image into smaller chunks? but there is no successful approach because I cannot find a distance measure of
convert from zero to the end, only by absolute value dimensions.
convert -crop-y -units-percentage 0x30 heart.png
Fig. 1 Input figure
I can do the task with LaTeX's
adjustbox but the output in the pdf file is not really end result but a presentation of it. So copying the image from the pdf document yields the original image.
So this approach failed.