int im_hist( in, plotofhist, bandno ) IMAGE *in, *plotofhist; int bandno;
creates a displayable histogram file for the image held by the image
The created displayable histogram is held in the IMAGE
== -1 a displayable histogram of all input bands
is created else the histogram of bandno only is created.
for rules on the size and scaling og the result.
All functions returns 0 on success and -1 on error.