MATLAB: Get grayImage from bitImage

binary imageImage Processing Toolbox

% Compute mean in 4-by-4 blocks
kernel = ones(4);
meanImage = conv2(double(grayImage), kernel, 'same') / numel(kernel);
% Compare actual image to mean image.
bitImage = grayImage >= meanImage;

From the bitImage is it possible to get back grayImage

Best Answer

No. There is no way to obtain the original gray level image from a binary image that has been created by thresholding that gray scale image. If you want the gray scale image later, be sure to save your gray scale image variable.

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blackImage = zeros(size(grayImage), 'uint8');
rgbImage = cat(3, blackImage, grayImage, blackImage);

Or you can use ind2rgb():

cmap = [zeros(256,1), (0:255)', zeros(256,1)]
rgbImage = uint8(ind2rgb(grayImage, cmap));

MATLAB: Convert image to bitmap map image without using for loop

Try this:

% Compute mean in 4-by-4 blocks
% kernel = ones(4);
meanImage = conv2(double(grayImage), kernel, 'same') / numel(kernel);
% Compare actual image to mean image.
binaryImage = grayImage >= meanImage;

There will be some errors at the edge of the image where the window does not fit onto the image, like it's only 4 by 3 or whatever. If this is important, then you can use conv2 twice, once to sum the image and once to count the pixels, then divide the gray level sum image from the pixel count image. But usually edge effects are not worth worrying about because they get removed later in the process naturally.

Best Answer

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MATLAB: Grayimage back to green

MATLAB: Convert image to bitmap map image without using for loop

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