MATLAB: Making some intensity values of image to zero

image processingMATLAB

hi..

How to zero the unwanted pixel intensity values of a image to zero.

Best Answer

if your image is 'a', try

a(a>threshold)=0;

or try

max(a,threshold);

which makes the values equal to your threshold. maybe it is useful

Related Solutions

MATLAB: Masked image displaying wrong intensity

Try this instead, which will select only the pixels in image dictated by the mask:

%to get the masked image without changing the dimension of the image
masked_image = image.*(mask > 0);
%or if you want just the pixels
masked_image_pixels = image(mask > 0);

Note that mask should really be a logical array, not a uint8 array, which is what (mask > 0) is taking care of for you.

In your original code, the issue is that you are using a uint8 mask matrix to multiply element-by-element with the image matrix. This means doing the following:

image .* mask
(value from the image matrix) x (255 or 0 from the "binary" uint8 mask matrix)

which would explain the large numbers.

MATLAB: Image Intensity

The mean of a particular pixel is just simply the pixel value, since there is only one sample - nothing really to take the mean of:

intensityValue = grayImage(100, 230); 
meanIntensityValue = mean(grayImage(100, 230));

Here, of course meanIntensityValue will equal intensityValue.

To get the mean of all the pixel values in the entire image, you can do any of these:

meanIntensityValue = mean2(grayImage);
meanIntensityValue = mean(grayImage(:));
meanIntensityValue = mean(mean(grayImage));

Best Answer

Related Solutions

MATLAB: Masked image displaying wrong intensity

MATLAB: Image Intensity

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