whitebalance_gpu(imageData)

function adjustedImage = whitebalance_gpu(imageData)
% WHITEBALANCE forces the average image color to be gray.
% Copyright 2013 The MathWorks, Inc.
 
% Find the average values for each channel
pageSize = size(imageData,1) * size(imageData,2);
avg_rgb = mean( reshape(imageData, [pageSize,3]) );
 
% Find the average gray value and compute the scaling factor
avg_all = mean(avg_rgb);
factor = max(avg_all, 128)./avg_rgb;
factor = reshape(factor,1,1,3);

% Adjust the image to the new gray value
imageData = gpuArray(imageData);
adjustedImage = uint8(bsxfun(@times,double(imageData),factor));
end