VPrepareColorImage - computes a prepared image to be displayed with
truecolor on.
  VPrepareColorImage(data, width, height, bits_per_rgb, min, max, ximage)
  unsigned char *data;
  int width, height;
  int bits_per_rgb;
  unsigned long min, max;
  XImage *ximage;                       /*RETURN*/
  VPrepareColorImage computes a prepared image to be displayed with
truecolor on. The input data format is RGB, RGB, ...., RGB. If bits_per_rgb
is 8, the input data is assigned to character pointer type. If
bits_per_rgb is 16, the input data is assigned to short pointer type. The
output data byte order depends on the X server, and VPrepareColorImage
gets this information from XImageByteOrder. In order to display the prepared
image stored in ximage, VPutImage should be called. The data stored by
the ximage structure (ximage->data) can be freed by calling free().
Return Value
  0 - work successfully.
  1 - memory allocation error.
  data - specifies an array of data to be computed.
  width,height - specifies the width and height in pixels of the image.
  bits_per_rgb - specifies the number of bits of each RGB component, the
        value is 8 or 16.
  min, max - the minimum and maximum gray values of the image data.
  ximage - returns precomputed image into the XImage structure.
Side Effects
Entry Conditions
  If the value of width, height, or bits_per_rgb is not valid, or
VCreateColormap is not called earlier, VPrepareColorImage prints an error
message to the standard error stream, produces a core dump file and exits
from the current process.
Related Functions
VPrepareGrayImage, VDisplayGrayImage, VDisplayColorImage, VPutImage, VGetImage, VTurnOnTruecolor, VTurnOffTruecolor.