[Solved] Total Number of pixels in an image [closed]

Question

The total number of pixels is not equal to the sum of values in your image.

sumOfAllPixelValues = sum(double(rgbImage(:)));
numberOfPixels      = numel(rgbImage);

The size on disk of an image is numberOfPixels*bytesPerPixel, where bytesPerPixel depends on the bit depth of an image (uint8 would be 8 bits=1 byte, for example.

To downsample the image by half, you can either reduce the bit depth (e.g. going from uint16 to uint8, or you reduce the number of pixels by sqrt(2) in height and width, for example using imresize.

Accepted Answer

The total number of pixels is not equal to the sum of values in your image.

sumOfAllPixelValues = sum(double(rgbImage(:)));
numberOfPixels      = numel(rgbImage);

The size on disk of an image is numberOfPixels*bytesPerPixel, where bytesPerPixel depends on the bit depth of an image (uint8 would be 8 bits=1 byte, for example.

To downsample the image by half, you can either reduce the bit depth (e.g. going from uint16 to uint8, or you reduce the number of pixels by sqrt(2) in height and width, for example using imresize.