How to calculate the various intensity value of different color channel of a color image? i need full code in matlab.

Dear I need to extract the following features of attached image. Please give me a solution to find out those features using matlab.

1. highest intensity value of red channel
2. lowest intensity value of red channel
3. mean intensity value of red channel
4. median intensity value of red channel.

[Guillaume]

Considering that any of these is trivial to do if you've bothered to learn the slightest bit of image processing, why can't you write the 4 lines required to achieve what you want?

Answer 1

[Florian Morsch]

You can use 'imhist()' and select the color you want by choosing the correct channel, red is channel 1. You will get a value of each pixel and how often its included in the image. After that you just extract the max. value, min. value (with 'find()' ) and calculate the mean (with 'mean()' ) and median (with 'median()' ).

[Md. Motiur Rahman]

will you describe elaborately? I am trying but can't figure out. thank you for your response.

[Florian Morsch]

Just go through the steps

1. Load your image

2. Define the RGB-channels, red is image(:,:,1)

3. Use imhist(wanted colour) to get the histogram

4. Check the variable you used for imhist() for the first and last value using find(). You can also use find() to get all rows with a value greater than zero, so you have all red pixels appearing from 0 to 255

5. Calculate the median() and mean() of your found values

[Md. Motiur Rahman]

i=imread('test.jpg');

red=i(:,:,1);

redhist=imhist(red);

redvalue=find(redhist);

is it correct to find all intensity value(including min and max) of red channel in variable redvalue?

[Walter Roberson]

No. The result of find() is array indices, which is not generally the same as original values.

[Florian Morsch]

If you want to find the first red value here, you would have to use find like this:

firstValue = find(redhist, 1);
[row, col] = find(redhist, 1);

This will give you the first value, the row and column. For the other values you want just change the find() to your needs.

[Guillaume]

Neither imhist nor find is required to answer the questions. Just min, max (or bounds if >=R2017a), mean and median.