Image compression is very important for remote control systems. One family of algorithms for image compression is JPEG. Digital images are represented as many blocks according to a JPEG algorithm. Generally, even if only one pixel is changed, the whole block has to be compressed and transferred if loss is undesirable or high video quality is necessary.
One example of the problem above occurs in a remote control system. FIG. 1 illustrates a conventional remote control system which uses image compression algorithms. The system includes a remote controller 120 and a KVM 104 with four computers 102. The remote controller 120 communicates with remote client 124 via network 122. The remote controller 120 consists of A/D converter 106, FIFO 108, I/O module 110, CPU 112, memory controller 114, memory 116 and network interface card (NIC) 118.
As a special example, owing to unsteady data sampled by AID converter 106, 200 pixels are changed in 200 separated blocks. The system has to compress and transfer 200 blocks, each consisting of 256 pixels, 16*16 pixels. The amounts of the data are very large. The system must be able to read and compress them quickly enough to meet the timing requirements for image refresh.
The timing problems are particularly severe where the sequence of digital images is distributed over a network with limited bandwidth. Some way must be found to compress the scattered pixels of digital images and thereby reduce the bandwidth required to transmit the images to their destinations over a network.
Compression techniques can be used to provide some relief to the transmission bottleneck. However, the amount of compression achieved by existing compression techniques does not provide both high quality and rapid transmission over network connections with limited bandwidth. The resultant transmission is slow and inefficient.