Images can be resized with the use of the command-line tool sizimg. Tests have shown that the quality resulting from sizimg surpasses that of any other commercially available software.
sizimg is a UNIX-style command-line tool to be used on the Macintosh using The Terminal application, or in the Command Prompt window on Windows. As a command-line tool, it has no user interface, but it can be very powerful when incorporated into scripts. In particular, it can be used in shell scripts to Batch process images.
The arguments and flags are described subsequently. Windows users may use a slash ("/") as well as a dash ("-") to indicate a flag. Note that the order of the flags does not matter, with the exception that flags with arguments must have their arguments immediately following.
An argument without a preceding flag is considered to be the input file path. This is a required argument.
The -o flag is immediately followed by a path name to the output file. It is a required argument.
The size of the output image may be specified either in percent or width and height. The percentage may have a decimal point in it, e.g. -% 70.71 will shrink the image by 70.71% (i.e. half the number of Pixels). The size of the output image must be specified, either with a percent or explicitly with width and height.
The desired width of the output image is specified in pixels. It is an error to also specify the percentage.
If the width is specified, but the height is not, the height is computed so that the output image has the same Aspect ratio as the input image. This can be especially useful for web pages, where it is not desirable to have images exceed a certain width, but it is OK to have an arbitrary height that might require scrolling. It is also useful for processing horizontal-circumference cylindrical or spherical panoramas (along with the -p h flag) to have a standard circumference or angular pixel density, but an arbitrary vertical field of view.
