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JPEG ENCODER

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01 Jul 2009 (Updated )

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

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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)
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Comments and Ratings (13)
14 Jul 2014 Raldi  
04 May 2013 kyo

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

:( HELP please

03 May 2013 kyo

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

29 Apr 2013 kyo

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

13 Dec 2012 sunil

this zipx conversion is not getting to compressed form

21 Apr 2011 vaalfegor  
05 Aug 2010 Tanyer Alan  
26 May 2010 elena elena  
25 May 2010 elena elena

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

03 May 2010 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 ...)?

23 Jan 2010 Ana Laura Rodriguez

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!

20 Aug 2009 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..

06 Jul 2009 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

Updates
19 May 2010

correction in jfif header format

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