In image processing filters are mainly used to suppress either the high frequencies in the image, i.e. smoothing the image, or the low frequencies, i.e. enhancing or detecting edges in the image. An image can be filtered either in the frequency or in the spatial domain.
A digital camera's internal FPGA may handle a large portion of the image processing directly as the image streams from the sensor, producing a processed output data stream rather than a series of individual images.
Here, I'm using VHDL to implement an image processing filter that blurs images.