vchan − manipulate multi-channel images

vchan [if=infile] [of=ofile] [c=channel] [ig=mfile] [-p] [-mp] [-ri]

Vchan performs a variety of fundamental operations on multi-channel image files. The default operation is to just select the first channel of each image. Note only one operation can be performed at a time; for multiple functions use a (piped) sequence of vchan commands.

For complex number operations: (1) no more than two channels are permitted, (2) single channels are extended to two channels, and (3) the result is always in float format. All numeric image types are supported for selection. For merging, bit file types are not supported.

c=<channel>

This option permits one channel of the image file to be selected. The channel specified must exist; the first channel is channel 1.

ig=<mfile>

This option specifies a second image file that is to be merged with the first file. For example, if ifile has 3 channels and mfile file has 2 channels the result will be a 5 channel file having the first three from ifile and the second 2 from mfile. For multi-image files images from mfile are matched to images of ifile using similar rules to that of vop(1).

-p

compute the power (sum of squares) for an image in real/imaginary representation. The resulting file is real valued.

-mp

Convert the input file, which is in real/imagnary representation to magnitude/phase representation.

-ri

Convert an input file in in magnitude/phase representation, to real/imaginary representation.

-c

The -c option specifies that a color image is to be converted to a monochrome image. When this option is specified, the input file must have at least three channels (red, green and blue). The output is computed by 0.299 * red + 0.587 * green + 0.114 * blue.

A. P. Reeevs