ISP

www.3dic.org/ISP

(Redirected from Image signal processor)

Image Signal Processor (ISP)


So what purpose does ISP have? Well, pixels are sensitive to light between some set of wavelengths, essentially they’re color agnostic. The way to get a color image out is to put a filter on top, usually a bayer pattern color filter, then interpolate the color of the pixels adjacent. Your 8 MP CMOS image sensor doesn’t sense red green and blue for each pixel, it senses one color for each, then ISP guesses the color based on what’s next to it. This is called demosaicing, and it’s probably the primary job of ISP, and there are many secret sauce methods to computing this interpolated image.


In addition, ISP does all the other housekeeping, it controls autofocus, exposure, and white balance for the camera system. Recently correcting for lens imperfections like vignetting or color shading imparted by the imperfect lens system (which you’ll add right back in with instagram, you heathen) has been added, along with things like HDR recombining, noise reduction, other filtering, face or object detection, and conversion between color spaces. There’s variance between the features that ISP does, but this is really the controller for getting that bayer data into a workable image array.