Intensity (luminance) calculation

How can I calculate the intensity level of the ith pixel (or the luminance of the ith pixel) of an 1024*1024 grey level image

Answer 1

[Image Analyst]

Knowing the row and column, you can get its gray level:

grayLevel = grayscaleImage(row, column);

The total number of rows and columns does not enter into it - all you need to know is the location of the pixel.

[Wisam S]

Dear, thanks a lot for your answer and help. I did not find “grayscaleImage” command in Matlab. Also, I am trying to find the luminance for each pixel (I need to find it as.. cd/m2)

[Image Analyst]

That was just an example name. I don't have the Crystal Ball Toolbox yet, so I can't see what name you are using in your program for the name of your gray scale image variable. What is it? Is it "I" or "A"? I certainly hope not. I hope you're using descriptive variable names and don't have code that looks like an alphabet soup of a bunch of single letter variable names. But whatever name it is, just use that instead of "grayscaleImage" in the code.

In general, that's how the forum works. People post code using variable names that they make up. Of course, you're free to use different variable names if you don't like the ones they picked. You can make up completely new names, or use names that you're already using in your existing code. Understand?

[Wisam S]

This is the code I use to calculate the luminance ..but the results are not correct.

I am trying to implement the paper in the below link

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CB0QFjAAahUKEwjEz4D_q8_IAhWEjg0KHficAN0&url=http%3A%2F%2Fwww.utexas.edu%2Fcola%2Ffiles%2F1516270&usg=AFQjCNEkeLqHe0NPzT-7rVQD9Etr62s1Xw&bvm=bv.105454873,d.eXY

[Wisam S]

thanks for your help sorry, I am a new here in this forum and I am not very good in Matlab

[Image Analyst]

OK, then the pixel value at row i, column j is img(i,j) since your image is named img instead of grayscaleImage.