Im not an expert in this field at all. Im trying to re-size batch images from the web and for the most part it is working great. I am running into images that are huge in size and re-sizing and compressing through mogrify just isnt working.
Ive used a standard desktop image re-sizer and it re-sizes the compresses the image to a reasonable size. The size is 500kb+ and they re-size it to 20kb. My mogrify cmd is leaving it just shy of 500kb.
Here is an example image http://c.shld.net/rpx/i/s/pi/mp/3962/225051167p?src=http%3A%2F%2Fwww.petraimages.com%2F500x500%2FTHRFBB1000P6.jpg&d=2ae05e1b6fd7950ae4fbbe2cc9039c0265073173
I am using the trim, resize (250x250), compress (JPEG), format (JPEG) cmd line args for mogrify. Ive tried playing around with the compression but no luck.
Seems your example picture consists mostly of an ICC color profile. This can be removed by adding
+profile icc
to the commandline options of mogrify or convert, for example
convert example.jpg +profile icc example_out.jpg
reduces the file size to 28kb.
convert example.jpg +profile icc +profile xmp example_out.jpg
results in 12 kb (even without reduction of pixel size or colors).