On-chip compression for HDR image sensors

An image compressing technique for High Dynamic Range (HDR) image sensors is introduced. Compression is performed in two steps: Pixel value coding optimization followed by DCT-based (Discrete Cosine Transform) compression. A floating point coding technique is first used with a common exponent shared between pixels of the same block, and then a DCT is applied to each group of pixels. This new concept, while maintaining low complexity architecture, shows a compression ratio of 75 % and retains a good image quality with a PSNR of about 40 dB.