JPEG ENCODER COMPLETE

PROGRAM CONSTRUCTS A JPEG FILE FROM THE INPUT BMP,TIFF FILE FORMATS.

Description

1.subsampling
2.level shifting --> dct -->quantization
3.DPCM OF DC COEFFICIENTS+HUFFMAN ENCODING.
4.ZIGZAG SCAN OF AC COEFFICIENTS
5.RUNLENGTH ENCODING + HUFFMAN ENCODING OF AC COEFFICIENTS.
6.ARRANGING THE AC DC COEFFICIENTS OF LUMA ,CB , CR ACCORDING TO JPEG STANDARD. (420 SUBSAMPLING) , REFER TO FIG 'itut81.JPG'.
7.COMBINING (LUMA,CB,CR) BITSREAMS OF 3 COMPONENTS.
7.BYTE STUFFING
8.TAKING 1 BYTE(8 BITS OF CODED STREAM) AND CONVERTING INTO DECIMAL EQUIVALENT.
9.WRITING JFIF HEADER FORMAT .
10. WRITING THE ENCODED BITSTREAM INTO THE ENTROPY CODED SEGMENT OF JFIF HEADER.

11.DECODING PART IS DONE BY THE IMAGE VIEWER ( DEFAULT IMAGE VIEWER LIKE MICROSOFT PICTURE , FAX VIEWER,PICASA, OR ANY OTHER VIWEWRS)

NOTE : I HAVE REPEATED THE DC ENTROPY AND AC ENTROPY CODING PROCEDURE , SEPERATELY FOR EACH COMPONENTS (LUMA,CB,CR). IT CAN BE AVOIDED BY WRITING A SINGLE FUNCTION EACH FOR AC AND DC ENTROPY ENCODING.

functions 'table_huff 'is same as 'table_bitcodval' .

THANKS

• MATLAB release: MATLAB 7.0.1 (R14SP1)
• Other Files: jpeg_encoder_complete.zipx, ; license.txt

[Ian]

The downloadable zip file contains another compressed file with a zipx extensions

7zip and other decompressers barf at this extension (they see the contents but return "unsupported compression method"

Is there any way that the zipx file could be compressed using a 'normal' compressor, tgz, zip, .7z, etc ?

Cheers

[Nikhil S Kumar]

 

[Ahmed Atteya]

hey, I have a project to implement a jpeg encoder from bmp to jpeg on matlab, but i'm facing some difficulties with the huffman encoding part. i don't know what to encode and what not to and i can't find good tutorials on the net, if you would be so kind to direct me to where i can find this information.. Thanks alot for your help..