image compression using jpeg
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- does doing dct followed by quantization and idct decompress the image?
- does run length encoding(rle) help to compress?
- when we save a file as jpeg and open it does it perform both dct and idct or only dct?
- how can i check if my image is compressed since both the original and output image are 256x256?
- in order to write a program to perform jpeg compression and display the compressed image do i have to use zig zag scanning and rle?
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Accepted Answer
Walter Roberson
on 8 Feb 2014
1. No.
2. Often enough to be useful, but not always.
3. You have not specified what "it" is.
4. In that situation there is no compression.
5. No. If you use lossless jpeg then the algorithm does not use those steps.
Compression involves processing data and creating an output that takes less storage than the original data. Decompression involves taking that lower-storage version and expanding it back to something (close to) the original data. The step you have missed in several of your questions is the "creating an output that takes less storage than the original data". Calculating dct and quantizing it probably does not take less storage -- but you can then take the quantized data and output only parts of it. The less you output the more the compression but the less accurately you can reconstruct the original data.
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More Answers (1)
jithin
on 17 Feb 2014
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Deepak Mishra
on 8 Sep 2022
i meant comparison between intraprediction and jpeg.. How can i prove that intraprediction produces better compression? and how can analysis filter cutoff frequency
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