1. An image processing method, adapted to an image capturing device, the image processing method comprising: capturing a first image with a first focal length, and capturing a second image with a second focal length, wherein the first focal length is focused on at least one main object; performing a geometric calibration procedure on the second image to produce the motion calibrated second image; performing a gradient operation on each pixel of the first image to produce a plurality of first gradients, and performing the gradient operation on each pixel of the motion calibrated second image to produce a plurality of second gradients; comparing each of the first gradients and the corresponding second gradient to generate a plurality of first pixel comparison results, and generating a first parameter map according to the first pixel comparison results; and producing a blending image according to the first parameter map and the first image, and producing an output image at least in accordance with the blending image, wherein the step of comparing each of the first gradients and the corresponding second gradient to generate the first pixel comparison results, and generating the first parameter map according to the first pixel comparison results comprises: dividing the second gradients by the corresponding first gradients to generate a plurality of gradient comparison values; and generating a plurality of parameters according to the gradient comparison values, and recording the parameters as the first parameter map.