imgsize - suggest width and height values to resize an image
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imgsize [-w [<widthmin>:]<widthmax>] width height
imgsize [-w [<widthmin>:]<widthmax>] image

The program suggests width/height combinations to resize an image.
The suggestions have the same aspect ratio as the original image.
If a maximum width ``widthmax'' is specified -- and optionally a
minimum width ``widthmin'' -- the program only suggests combinations
for this width range.
If no maximum width is specified the program suggests sizes for
decreasing the image size.
Each suggestion is shown in one line, containing classification,
width and height.
The suggestions are classified as follows:
- If the scale factor is not a natural number the first character
  in the line is '-'.
- If the scale factor is a natural number bot not a power of 2
  the first character in the line is '+'.
- If the scale factor is a power of 2 the first character in the
  line is '*'.