difference between same images

Hi,

I have an image matrix which has a size of "mxnx3 uint8". I created a zero matrix by using zeros(m,n) (lets call it "image_filled"). So that, mxn double matrix is formed. Then I tried to copy the pixels of image matrix sample by sample to the zero matrix. I figured out that there has been a contrast difference between two images. Why this happens? How can I fix it?

Note: Image on the left is image_filled. Right side is original_image. Please do not mind the black lines on the images

Thanks so much.

Answer 1

[Image Analyst]

They look gray scale, so let's convert to gray scale first, and then do the copying

[rows, columns, numberOfColorChannels] = size(rgbImage);
% Get grayscale image from original RGB image.
if numberOfColorChannels == 3
    grayImage = rgbImage(:,:, 2); % Extract green channel only - it's usually the least noisy one.
else
    grayImage = rgbImage;
end
image2 = zeros(rows, columns);  % Not sure why you did this because it's not necessary.
% Now copy gray image into image2
image2 = grayImage;

A contrast difference could happen if you used different parameters for imshow. For example

imshow(grayImage, []); % Stretch contrast
imshow(image2); % No contrast stretch.