Error validating server certificate svn
For a reasonable explanation of how it works, please see this example of Huffman coding an ASCII string and the overview from Wikipedia.For more details, please see my article on Optimized JPEGs - optimizing the huffman tables, particularly the first introductory sections and the section near the end titled "Standard Huffman Tables".bytes, DCT coefficients, etc.) and encodes them with variable length codes that are assigned according to statistical probabilities.A frequently-used symbol will be encoded with a code that takes up only a couple bits, while symbols that are rarely used are represented by symbols that take more bits to encode.A JPEG file contains up to 4 huffman tables that define the mapping between these variable-length codes (which take between 1 and 16 bits) and the code values (which is an 8-bit byte).
The above hex dump datastream shows the beginning of the Start of Scan (SOS marker (128 pixels x 8 bits/channel x 3 channels x 1 byte/8 bits).
If one uses optimized JPEG encoding, it is possible to reduce the image content size even further.
In the example image, the optimized version has much smaller huffman tables ( The scan data is: FC FF 00 E2 AF EF F3 15 7F To help resiliency in the case of data corruption, the JPEG standard allows JPEG markers to appear in the huffman-coded scan data segment.
After quantization, huffman / entropy coding is one of the more significant contributors to the file size savings in JPEG compression.
This page provides a tutorial on how the huffman coding works in a JPEG image.