How to draw histogram of hsv image?

Using imhist we canget histogram of grayscale image. How to draw histogram of hsv image?

Answer 1

[Image Analyst]

Try this

hsvImage = rgb2hsv(rgbImage);
hImage = hsvImage(:, :, 1);
sImage = hsvImage(:, :, 2);
vImage = hsvImage(:, :, 3);
figure;
subplot(2,2,1);
hHist = histogram(hImage);
subplot(2,2,2);
sHist = histogram(sImage);
subplot(2,2,3);
vHist = histogram(vImage);

[Mario Castro]

this code do not show any result at all. HSV values are represented in % and degrees.

[Image Analyst]

Of course it does. Did you even run the code? You need to have rgbImage already read in. Here, here is a more complete demo:

rgbImage = imread('peppers.png');
hsvImage = rgb2hsv(rgbImage);
hImage = hsvImage(:, :, 1);
sImage = hsvImage(:, :, 2);
vImage = hsvImage(:, :, 3);
figure;
subplot(2,2,1);
hHist = histogram(hImage);
grid on;
title('Hue Histogram');
subplot(2,2,2);
sHist = histogram(sImage);
grid on;
title('Saturation Histogram');
subplot(2,2,3);
vHist = histogram(vImage);
grid on;
title('Value Histogram');
subplot(2,2,4);
imshow(rgbImage);

Answer 2

[Anand]

If you need the histogram only for visualization purposes, you can obtain it using the colorThresholder app.

Open the RGB image in the colorThresholder app and select the HSV color space. The right-hand pane will show histograms in H,S and V.

Open the image in the Color Thresholder:

 >> colorThresholder(rgbImage)

Select HSV Color space.

[sya zamani]

Hi Anand, Sorry for the late question, do you know how to display the HSV histogram as shown in the colorThresholder app? Thanks in advance.

Answer 3

[Yoon Thiri Zaw]

Can i find threshold values using Lab based color histogram? If having code, tell me please!

[Image Analyst]

Depends on what threshold divides your color channel into foreground and background. No one can tell without seeing your image and an explanation of what you want (foreground) and what you don't want (background) to segment.