This code implements a JPEG encoder and decoder for girl.png image with 8-bit grey scaled pixels, with the following steps:
1- Reads and divides the image into blocks of 8x8 pixels.
2- Performs DCT on each block.
3- Performs quantization step per 8x8 block using 3 different quantization tables.
4- Transforms each block from 2-D into 1-D vector using zig-zag pattern.
5- Performs run-length encoding to compress the stream of zeros that may result due to quantization.
6- Performs Huffman to encode the final stream into a further compressed bit stream.
7- Performs Huffman decoding to decode the Huffman encoded stream.
8- Performs run-length decoding.
9- Transforms the 1-D vector into groups of 8x8 matrices.
10- Multiplies each group by the quantization tables.
11- Performs IDCT on each 8x8 pixel group.
12- Combines the 8x8 pixel groups into a single image and saves it back to a file.
13- Compares the original image with the compressed image when using each quantization table in step (3).
- DCT, IDCT
- Quantization, Inverse Quantization
- Zig-Zag scan, Inverse Zig-Zag scan
- run-length encoding/ decoding
- Huffman encoding