It is my understanding that you are not able to perform a multiplication operation (pixel*5) on individual pixels of your blocks. When you multiply your pixel by 5, it shows 255 every time.
This might be because the pixel values in MATLAB vary from 0 – 255 (0 being the minimum and 255 being the maximum).
When you try to modify a pixel to anything above 255, MATLAB will automatically keep the pixel at 255.
If your application requires you to scale a particular pixel by 5 times as compares to the other pixels,
you could scale all pixels down by a factor of 5 and then multiply the required pixel by 5.
I = imread('image_path'); %replace image with your image path e.g.: C://users/documents/1,jpg
I=I/5; %scale down all pixels by 5
%perform your operations here
%
%
%
%all the pixels will be dim, except the pixels you multiply by 5.
Munish Raj
