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code for jpg manipulation

Posted on 1999-01-21
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Last Modified: 2010-04-15
i need a source code for mnipulating jpg images. iwant to paste a couple of jpgs on a different larger size jpg.

the source will get the jpgs paths as arguments, and execute the copy and paste.
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Question by:liorliat
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by:Tommy Hui
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Go to http://www.ijg.org for a library that can manipulate JPEG files.
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by:liorliat
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i'm sorry, but i have been informed that the application sould run on linux/unix, so i'll ask this question on linux.  about ijg,the only code i could find was JPEG compression and decompression. nothing about other manipulations. i'll be glad if you instruct me to a specific place to get code from.
thanks  :)
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hougaard earned 300 total points
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Due to the fact that jpg is a compressed format you will have to do your stuff in steps:

1. Create the target bitmap in memory (uncompressed) malloc(width*height)
2. Load and uncompress the jpg's to another memory location
3. Perform a pixel to pixel convertion from the loaded (uncompressed) jpg into the target bitmap (something like:

XOffset = 100 // X Offset into target bitmap
YOffset = 100; // Y Offset into target bitmap
for (x = 0; x <= Width; x++)
  for (y = 0; y <= Height; y++)
  {
   // DOne with arrays for easy reading - sould be pointers into the allocated bitmap memory
    TargetPixel[Xoffset + x,YOffset + y] = SourcePixel[x,y]
  }

4. Compress the target bitmap (With the jpg compress function from ijg.org)
5. Save the jpg.
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Author Comment

by:liorliat
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i know the algorithm, i need the code...  i know it's a lot of code,i need somthing written, like the written files of Tom Lane and the independed jpg group.(i didn't find there what i was looking for).  
thanks a lot   :)

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Expert Comment

by:AlexVirochovsky
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See to http://user.cs.tu-berlin.de/~uzadow/paintlib/
for C++ code of jpg manipulations
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Author Comment

by:liorliat
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hougaard, thanks you 4 your answer. i'm sorry about the confused requests....   this time it's finall...   i need a  c  code for compression\decompression jpg files.  i have the IJG code, but it's too much, and too big for me.
can you help me with a precise code ?
thanks(again) and sorry(again) for the bother..
:)
 

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Expert Comment

by:hougaard
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The best stuff is the IJG code, here is what you need to do with it!

1. Read the libjpeg.doc document ... Good starter info
2. Compile the example.c (Has read and write jpeg file functions!)
2.1 In order to this you will have to build the libjpeg.lib (the example.c includes the libjpeg.h)
2.2 Study the way the library stores the pixels - from this points it becomes easy to do what you want!
4.Change the example.c to include a main()
5. Have a Party!
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