[magick-users] square gradient png bigger in size if you save them vertically compared to horizontally

[bw]

Hi,

I read ones on a website (I am looking for the link!!) why a square gradient
image with its lines horizontally aligned was smaller than the same image
turned 90 degrees (so the lines are vertically aligned).

If I am remembering this correctly this had to do due to the fact that the
compression algorithm scans horizontally per line of pixels and compresses
the same color pixels.

Does anybody got a bookmark/link to the explanation page of this behavior?

thx,

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