Image Processing Toolbox

Image Histogram

An image histogram is a chart that shows the distribution of intensities in an indexed or intensity image. The image histogram function imhist creates this plot by making n equally spaced bins, each representing a range of data values. It then calculates the number of pixels within each range. For example, the commands below display an image of grains of rice, and a histogram based on 64 bins.

• I = imread('rice.tif');
  imshow(I)
  figure, imhist(I,64)
  
  
  

Figure 10-4: Rice.tif and Its Histogram

The histogram shows a peak at around 100, due to the dark gray background in the image. For information about how to modify an image by changing the distribution of its histogram, see Intensity Adjustment.

Image Contours

Summary Statistics