Image Processing Toolbox

imhist

Display a histogram of image data

Syntax

• imhist(I,n)
  imhist(X,map)
  [counts,x] = imhist(...)
  

Description

imhist(I,n) displays a histogram with n bins for the intensity image I above a grayscale colorbar of length n. If you omit the argument, imhist uses a default value of n = 256 if I is a grayscale image, or n = 2 if I is a binary image.

imhist(X,map) displays a histogram for the indexed image X. This histogram shows the distribution of pixel values above a colorbar of the colormap map. The colormap must be at least as long as the largest index in X. The histogram has one bin for each entry in the colormap.

[counts,x] = imhist(...) returns the histogram counts in counts and the bin locations in x so that stem(x,counts) shows the histogram. For indexed images, it returns the histogram counts for each colormap entry; the length of counts is the same as the length of the colormap.

Note    For intensity images, the n bins of the histogram are each half-open intervals of width . In particular, the th bin is the half-open interval    The scale factor depends on the image class. is 1 if the intensity image is double; is 255 if the intensity image is uint8; and is 65535 if the intensity image is uint16.

Class Support

The input image can be of class logical, uint8, uint16, or double.

Example

• I = imread('pout.tif');
  imhist(I)
  
  
  

See Also

histeq

hist is in the MATLAB Function Reference

imfinfo

imhmax