Databases Reference
In-Depth Information
F I GU R E 11 . 18
Left: Reconstructed image using differential encoding at 1 bit per
pixel. Right: Reconstructed image using JPEG at 1 bit per pixel.
F I GU R E 11 . 19
Left: Reconstructed image using differential encoding at 1 bit per
pixel using median predictor and recursively indexed quantizer.
Right: Reconstructed image using JPEG at 1 bit per pixel.
For the boundary pixels we use the simple prediction scheme. At a coding rate of 1 bit per
pixel, we obtain the image shown in Figure
11.19
. For reference we show it next to the JPEG-
coded image at the same rate. The signal-to-noise ratio for this reconstruction is 29.20 dB
(PSNR 38.28 dB). We have made up two-thirds of the difference using some relatively minor
modifications. We can see that it might be feasible to develop differential encoding schemes
that are competitive with other image compression techniques. Therefore, it makes sense not
to dismiss differential encoding out of hand when we need to develop image compression
systems.
