vhist − compute a histogram of an image.

vhist [if=infile] [of=ofile] [m=<value>] [-z] [n=] [l=] [h=] [-v]

Vhist computes a histogram for an image file. The output is in the format of a 2D vector which may be plotted with vplot.

The defualt range for pixels is 0 to 255. For non-byte pixels the limits must be explicitly stated on the command line wiht the l= and h= options. Currently thre is no autoscale option.

m=value

set the max bin value, default is 256

n=value

set the number of bins in the histogram. The default for byte images is 256 and for other image types is 100.

l=value

set the lowest pixel value that will be considered in the histogram

h=value

set the highest pixel value that will be considered in the histogram

-z

set bin zero of the result to zero

-i

compute a histogram vector for every image in the file. By default, a single histogram for all images is computed.

im=mask

specifies a binary valued mask image that has the same dimensions as the if= image. Only pixels that are selected by the mask values are considered in the histogram.

-v verbose option

A. P. Reeves