Clear Filters
Clear Filters

what does a histogram represent of a image ?

5 views (last 30 days)
What is the x axis and y axis in a histogram of a image. how does it work ?

Accepted Answer

Image Analyst
Image Analyst on 28 Dec 2014
The x axis is the gray level (intensity, brightness) of the image. The y axis is the count of how many pixels in the image have the gray level. It's often useful to look at the histogram to figure out how to threshold the image to create a binary image of foreground and background objects so that you can do connected components labeling and measurement of various characteristics with the regionprops() function.
  3 Comments
Farjana Yeasmin
Farjana Yeasmin on 30 Dec 2014
Is the ans is approved for both RGB and gray scale image ?
Image Analyst
Image Analyst on 30 Dec 2014
Yes. Normally you'd take the histogram of each color channel separately.
% Extract the individual red, green, and blue color channels.
redChannel = rgbImage(:, :, 1);
greenChannel = rgbImage(:, :, 2);
blueChannel = rgbImage(:, :, 3);
% Now take histograms of the individual color channels.
[countsR, grayLevelsR] = imhist(redChannel);
[countsG, grayLevelsG] = imhist(greenChannel);
[countsB, grayLevelsB] = imhist(blueChannel);

Sign in to comment.

More Answers (0)

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!