问题
As seen here: http://www.imagemagick.org/Usage/resize/#shrink the option:
-resize 64x64>
only resizes if width and height exceeds 64 px. But how about to do something like that if works:
-resize 64>x
or
-resize 64x'ignores'>
in other words if only width exceeds this size. Is this possible?
回答1:
You can easily achieve that by using an 'unlikely large' height value:
convert orig.png -resize '64x10000>' scaled.png
This will resize the original PNG only if its width was larger than 64 pixels or if its height is larger than 10 000 pixels. But the chance that the command will ever encounter an input that's higher than 10 000 pixels is very low. So it will (almost) only encounter input files where the width value matches.
Original PNGs with widths lower than 64 pixels will remain untouched (unless their height is above 10 000 pixels...).
来源：https://stackoverflow.com/questions/12273203/how-to-resize-image-only-if-width-exceeds-with-graphics-image-magick