File Exchange

image thumbnail

JPEG ENCODER

version 1.1 (38 KB) by

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

3.33333
7 Ratings

13 Downloads

Updated

View License

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

Comments and Ratings (13)

Raldi

Raldi (view profile)

kyo

kyo (view profile)

Is there anybody have the correct code ???
the image file output is invalid why !!!

:( HELP please

kyo

kyo (view profile)

To decompresse the file.zipx, use this software: PeaZip

kyo

kyo (view profile)

the result image is broken why ???
i think that JP_STREAM is not orgianized correctmy !!

sunil

sunil (view profile)

this zipx conversion is not getting to compressed form

vaalfegor

Tanyer Alan

Tanyer Alan (view profile)

elena elena

elena elena

I have downloaded the ZipX utility but to avail. But it is need a password. How can I open it

Kenneth Sala

I have downloaded the ZipX utility but to avail. Nothing I have (WinZip , RAR, ...) including this ZipX utility can decompress your files (this one and the "encoder + decoder" file). Could you PLEASE make your files available on MathWorks in some more standard compression format (zip or rar or ...)?

Hi! In the function DC_Huffman you compare G with different categories of table A, where is that table? it contains information about variables u,c,d,x,y and h? Could you explain me this a little better? Thank you for your help!

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..

Ian

Ian (view profile)

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

Updates

1.1

correction in jfif header format

MATLAB Release
MATLAB 7.0.1 (R14SP1)

Download apps, toolboxes, and other File Exchange content using Add-On Explorer in MATLAB.

» Watch video