The two alternative solutions for performing image filtering presented so far have their origin in general two-dimensional signal processing theory. This means that they should be expanded for three-dimensional signals when we have to deal with colored image filtering. The process is pretty straightforward and involves repeating the process for all three separate colored channels. But why do that, when we have a function that takes care of checking the image before applying the filter and then selecting the correct method?

This specialized function is called imfilter and it is designed for handling images, regardless if they are grayscale or color. This function can implement both filtering methods described in previous paragraphs and it can also define the result to be same or full. Its extra functionality comes in the selection of the way it handles boundary values, and the automatic processing of color images. Furthermore, this function performs the needed conversions, in case the image input is integer-valued. Combined with the fspecial function, this will probably be your most valuable tool in MATLAB when it comes to image filtering.