MATLAB: How to calculate the total white dots/ white region in this image

image processingImage Processing ToolboxMATLAB

hi, i'm beginner of matlab. Please show me the ways to calculate the total white pixel/regions that appear on this image..thanks http://imageshack.us/photo/my-images/841/result2cars.jpg/ http://img841.imageshack.us/img841/810/result2cars.jpg

Best Answer

To read in the image, use

M = imread('result2cars.jpg');

Because your image is a grayscale image, M is just a matrix. Each entry corresponds to one pixel. The entries are integers from 0 (black) to 255 (white). To calculate the number of completely white pixels, use

sum(M(:) == 255)

If you accept very light gray as white as well, use

sum(M(:) > t)

where t sets the white tolerance. For example, using t = 128 would count all pixels who is brighter than 50% gray as being white.

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MATLAB: Black and white image

Try this

[counts, grayLevels] = imhist(grayImage, 256);
if sum(counts(2:end-1)) > 0
  % It's not pure black and white
end
% Get map of non-0 and non-255 pixels
grayPixels = grayImage > 0 & grayImage < 255;
% Get pure black and white image
bw = grayImage; % Initialize

bw(grayPixels) = 0; % Zero out any gray pixels.
% Get gray pixels only
grayOnly = grayImage; % Initialize
grayOnly(~grayPixels) = 0; % Zero out any pure 0 or pure 255 pixels.

MATLAB: How to create a white image

Try this to create a grayscale image:

whiteImage = 255 * ones(N, M, 'uint8');
imshow(whiteImage);

To create an RGB image, try this:

whiteImage = 255 * ones(480, 640, 3, 'uint8');
imshow(whiteImage);

Best Answer

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