If you're talking about a simple crop of the image, there should not be any change in the pixel colors. If you want to maintain the same number of pixels AND zooming the image, there is a resampling of the pixels and the RGB values will change.
hi , real pixel value is the same as intensity of the pixel . if you mean simple zooming by cropping the photo , it doesn’t make change ; but it will be different if you zoom by ( for example ) bilinear interpolation or using repetitive pixels!