NAME

xil_rescale − rescale the data in an image

SYNOPSIS

#include <xil/xil.h>

void xil_rescale (XilImage src,

XilImage dst,
float ∗scale,
float ∗offset);

DESCRIPTION

This routine performs a pixel-by-pixel rescaling of the data in a src (source) image by first multiplying each pixel value by a scale factor and then adding an offset. The result is stored in the dst (destination) image. For an n-band image, each array of constants must contain n floats The values in band 0 are scaled by scale[0] and added to offset[0], and so on. 

Pixel values are clipped according to image data type.  In this function, a floating point intermediate value is calculated, so clipping/rounding is done after both the multiplication and the addition have occurred. 

ERRORS

For a complete list of XIL error messages by number, consult Appendix B of the XIL Programmer’s Guide. 

EXAMPLES

Rescale a 4-band short src image into the range of XIL_BYTE, and store the result in dst:

XilImage src, dst;
float scale_values[4], offset_values[4];
src=xil_create(State, 512, 512, 3, XIL_SHORT);
dst=xil_create(State, 512, 512, 3, XIL_SHORT);
/∗ scale factors for each band ∗/
scale_values[0] = 127.5/32767.0;
scale_values[1] = 127.5/32767.0;
scale_values[2] = 127.5/32767.0;
scale_values[3] = 127.5/32767.0;
/∗ offset factors for each band ∗/
offset_values[0] = 127.5;
offset_values[1] = 127.5;
offset_values[2] = 127.5;
offset_values[3] = 127.5;
xil_rescale(src, dst, scale_values, offset_values);

NOTES

Source and destination images must be the same data type and have the same number of bands.  In-place operations are supported. 

SunOS 5.6  —  Last change: 03 August 1993