The feature extraction step of my algorithm, applies some filter on data and use the value of filtered pixels as the feature of original pixels of image.
My problem is that I need the feature of only small subset of pixels(threshold-ed pixels), not all of the image. and it is time consuming to filter all of the image, instead of only some pixels.
My question is how can I filter only selected pixels of an image? Is there any matlab function for this purpose?(I think I can not use imfilter)