| .TH CONVERSIONS 3 "28 June 1990" |
| .SH NAME |
| im_scale, im_scaleps \- scale an image to unsigned char image |
| .SH SYNOPSIS |
| #include <vips/vips.h> |
| |
| int im_scale(in, out) |
| .br |
| IMAGE *in, *out; |
| |
| int im_scaleps(in, out) |
| .br |
| IMAGE *in, *out; |
| .SH 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. |
| |
| .B 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. |
| .SH RETURN VALUE |
| Each function returns 0 on success and -1 on error. |
| .SH SEE ALSO |
| im_any2c(3), im_c2amph(3), im_clip(3) |
