Evaluation of lossless image compression algorithms for CFA data

The CCD sensors of a digital camera are arranged in a colour filter array fashion where each element records only one colour. While the majority of images captured with digital cameras are recorded in JPEG format, preserving the raw image data becomes more and more important. Typically each manufacturer uses their own proprietary raw image format and usually no compression is applied. In this paper we investigate what savings in terms of storage space can be gained by applying lossless compression to the raw colour filter array data. Based on an image set of 200+ images we evaluate eight different compression algorithms in terms of compression efficacy and compression speed. The results show that JPEG-LS seems to be best suited to be employed in digital cameras offering good compression ratios coupled with high speed.