MATLAB: Finding pixels having a specific intensity value

intensity

Hi, I want to find the pixels or the infinitesimal areas having an intensity value of 255 in a grayscaled image and calculate the area they occupy in the image. Can anyone help me?

Best Answer

To "find the pixels", as in getting the rows and columns where they live , do this:

[rows, columns] = find(grayImage == 255);

To get the area in pixels, use the formula like Walter gave.

Related Solutions

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));

MATLAB: Finding a closed region

Create a mask of your regions (blobs). Then use the fourth syntax of REGIONPROPS to specify both the mask and the intensity image. With that syntax, you can calculate the 'PixelValues' of each blob, and use whatever test you want to classify them.

Alternatively, for this simple case, you can request 'MinIntensity' and 'MaxIntensity' properties of the blobs. Then, if min==255 AND max==255, all pixels in the region must be 255.

Cheers,

Brett

Best Answer

Related Solutions

MATLAB: Image Intensity

MATLAB: Finding a closed region

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