can any one explain this code it is for extracting green object from a image . i want know about the methodology used here ?

r1 = greenball2(:, :, 1); g1 = greenball2(:, :, 2); b1 = greenball2(:, :, 3); justGreen2 = g1 - r1/2 - b1/2;

Answer 1

[Image Analyst]

It's measuring how much brighter the green component is than the average of the red and blue component . And it's done on the entire image so the calculation is basically pixel by pixel.

[anji venkat]

thank u sir why we used r1 = greenball2(:, :, 1); to represent red and g1 = greenball2(:, :, 2); green what notation (:,:,1) or (:,:,2) or (:,:,3) represents ?

[Image Analyst]

The notation for 3D color image arrays in MATLAB is arrayName(rowIndex, columnIndex, colorChannelIndex). And colon : means "all". So, for example arrayName(32,:,3) means all columns in row 32 of color channel #3 (the blue channel). And arrayName(:,:,2) means all rows and all columns of color channel #2 (the green channel), so basically it's the green color channel of the entire image.