xil_histogram_get_nbands(3)

NAME

xil_histogram_get_nbands, xil_histogram_get_nbins, xil_histogram_get_limits, xil_histogram_get_values, xil_histogram_get_info − histogram attributes

SYNOPSIS

#include <xil/xil.h>

unsigned int xil_histogram_get_nbands ( XilHistogram histogram);

void xil_histogram_get_nbins ( XilHistogram histogram,

unsigned int ∗nbins);

void xil_histogram_get_limits ( XilHistogram histogram,

float ∗low_value,
float ∗high_value);

void xil_histogram_get_values (XilHistogram histogram,

unsigned int ∗data);

void xil_histogram_get_info ( XilHistogram histogram,

unsigned int ∗nbands,
unsigned int ∗nbins,
float ∗low_value,
float ∗high_value);

DESCRIPTION

These routines read the values of histogram attributes and the intensity-level information stored in the histograms. Histograms are used to obtain information about the distribution of pixel values in an image. Create histograms with xil_histogram_create(3).

xil_histogram_get_nbands() returns the number of bands represented by the histogram. For example, a histogram with three bands can be thought of as a cube of data, with each axis representing a single band.

xil_histogram_get_nbins() fills in a user-supplied array, nbins, with values representing the number of histogram bins for each histogram band.

xil_histogram_get_limits() fills in user-supplied arrays, low_value and high_value, with floating point numbers that represent the value of the first bin and last bin in each band.

xil_histogram_get_values() fills in the user-supplied array, data, with the unsigned integer values that make up the histogram data. The data are aligned so that values along the first band’s axis are contiguous.

xil_histogram_get_info() combines the function of other attribute functions. nbands is filled with the number of bands in the histogram; nbins is filled with the number of bins per band, one for each band. low_value and high_value are arrays that contain the low and high values for each band.

ERRORS

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

EXAMPLES

Create an array to hold the histogram data and retrieve the data:

XilHistogram histogram;
unsigned int nbands;
unsigned int ∗bins, ∗data;
int i, total_entries;
nbands = xil_histogram_get_nbands (histogram);
bins = (unsigned int∗) malloc(nbands ∗ sizeof(unsigned int));
xil_histogram_get_nbins (histogram, bins);
total_entries = 1;
for (i=0; i<nbands; i++)
total_entries ∗= bins[i];
data = (unsigned int∗) malloc(total_entries ∗ sizeof(unsigned int));
xil_histogram_get_values(histogram, data);

Museum