ImageValue

ImageValue[image,pos] gives the interpolated value of image at position pos.

ImageValue[image,pos,"type"] gives the value converted to the specified type.

Examples

Get the interpolated pixel value at a position:

img = ExampleData[{"TestImage", "Lena"}];
ImageValue[img, {100.5, 200.5}]

Please visit the official Wolfram Language Reference for more details.