Hybrid images are static images that changes in interpretation as a function of the viewing distance. Hybrid image is combination of low pass component of one image and high pass component of other. At a distance, only the low frequency part of the image signal is visible while with close look we are able to see higher frequency components.
Image filtering or convolution is a fundamental image processing technique. It helps in modifying or enhancing an image. This technique involves sliding a kernel over input image and performing convolution sum to update pixel value at the centre of the kernel. Different types of kernel can be used to perform different tasks like smoothing, sharpening, and edge detection etc.