imhist function is not generating

i=imread('toycars2.png');

figure

subplot(1,2,1)

imshow(i)

subplot(1,2,2)

imhist(i)

when ı run this code it looks like this.why doesn't it show the histogram?

Answer 1

[DGM]

imhist() expects its inputs to be single-channel images. You could either take the histogram of some overall brightness metric:

i=imread('sources/table.jpg');
figure
subplot(1,2,1)
imshow(i)
subplot(1,2,2)
imhist(rgb2gray(i)) % this is luma

or you could set up everything and do histograms for each channel

i=imread('sources/table.jpg');
figure
subplot(3,2,[1 3 5])
imshow(i)

for c=1:3
	subplot(3,2,c*2)
	imhist(i(:,:,c))
end