NAME
im_scale, im_scaleps - scale an image to unsigned char image
SYNOPSIS
#include <vips/vips.h>
int im_scale(in, out)
IMAGE *in, *out;
int im_scaleps(in, out)
IMAGE *in, *out;
DESCRIPTION
These functions scale a non-complex image to a displayable byte
(unsigned char) image.
im_scale() scales the image held by image descriptor to a byte
(unsigned char) image and writes the result on the image descriptor
out. Sizes and the number of the bands of out are identical to those
of input. Input image should be non complex and can have any number of
channels. The output is scaled between 0 and 255; if the image is
multiband the maximum value of all channels is set to 255 and the
minimum to 0. In all cases, rounding is performed by adding .5 to the
scaled values.
im_scaleps() scales to 0 - 255 by mapping each pixel through the
equation
log10(1.0 + pow(x, 0.25))
and then multiplying by a factor so that the image maximum is 255.
This transformation highlights both low and high spatial frequencies in
the power spectrum. The images produced by this non-linear
transformation are only for display and not for further processing.
RETURN VALUE
Each function returns 0 on success and -1 on error.
SEE ALSO
im_any2c(3), im_c2amph(3), im_clip(3)
28 June 1990 CONVERSIONS(3)