Cropper converts a set of jpg, jpeg, png and gif files to a common size,
e.g.  to use in composing an animated gif.  It does not handle webp files.
It uses a mixture of cropping and scaling.  All you have to do is specify
the desired size.  It will ignore all files except those with extension
.jpg .jpeg .png and .gif.
To convert a single file, type:
  java.exe -jar C:\com\mindprod\cropper\cropper.jar  200 300 rabbit.gif
where 200x300 pixels is the desired size.  The results replace the old
file, so you had better make a backup just in case this is not what you
want.
You can also list several files on the command line:
  java.exe -jar C:\com\mindprod\cropper\cropper.jar 200 300 rabbit.gif C:\mydir\cat.png
To use convert the current directory of jpg, png and gif files:
  java.exe -jar C:\com\mindprod\cropper\cropper.jar 200 300 .
to convert a whole directory tree of images:
    java.exe -jar C:\com\mindprod\cropper\cropper.jar 200 300 -s E:\imagedirs
Sorry no wildcards, just . , and ..
DON'T USE WILDCARDS unless you deeply understand how they work.  Windows
expands them, not cropper, and feeds them to cropper (or any other
program) as a giant list of all the directories and files in the current
directory.  Cropper will thus tend process all the files in your
directories, when you just meant to process the files in the current
directory.
If you have the jar extension set up as executable, you can abbreviate:
  C:\com\mindprod\cropper\cropper.jar 200 300 .
There is a companion utility called rightsize that will tell you which
files are are too big or too small.
The nested green rectangles icon is intended to suggest cropping an image
down.