GD would be the way to go, given "Image::Resize - Simple image resizer using GD". I'm currently using it for doing PNG->JPG conversion/sizing and the docs mention that GD supports WBMP (which I assume means "Windows .bmp"), although I wasn't able to quickly find a complete list of formats supported by GD.

Some sample code to help get you started:

  binmode $img_fh;
  local $/;
  undef $/;
  my $img = GD::Image->new($img_fh) or die "Failed to read image file:
+ $!\n";
# ...
  my $fh;
  my $fullpath = "$path/$filename" . ($png_img ? '.png' : '.jpg');
  open $fh, '>', $fullpath or die "Failed to write image file: $!\n";
  binmode $fh;
  print $fh ($png_img ? $img->png : $img->jpeg);
  close $fh;
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