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Questions tagged [dct]

Discrete Cosine Transform (DCT).

A discrete cosine transform (DCT) expresses a sequence of finitely many data points in terms of a sum of cosine functions oscillating at different frequencies. DCT's are important to numerous applications in science and engineering, from lossy compression of audio (e.g. MP3) and images (e.g. JPEG) (where small high-frequency components can be discarded), to spectral methods for the numerical solution of partial differential equations.

More information on Wikipedia: Discrete cosine transform .

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Questions regarding DCT8x8 CUDA sample

I have a questions regarding the Sample provided by Nvidia called DCT8x8 which is applied to an image to execute the algorithm in parallel. more info: http://developer.download.nvidia.com/compute/DevZone/C/html/C/src/dct8x8/doc/dct8x8.pdf The code…
user3025898
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quantization of dct image for steganography

I hav a greyscale image. I did 8x8 blocks and computed each of their DCTs. I want to quantize the DCT coefficients and then replace their LSBs with my secret message bits. How exactly do I quantize the coefficients? Should I use the quantization…
shiladitya
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incorrect result of fast dct algorithm

I want to implement the Loeffler fast dct algorithm by VHDL. Prior that i checked the algorithm result for a given data such below: x=[0 1 2 3 4 5 6 7] then i calculated dct equivalent using this algorithm and result be came: y=[28 -8.47 0 …
user3625280
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how to parallelize dct (for loops) in cuda

How to parallelize four nested for loops in cuda in case of dct i have four nested for loops i want my dct function in cuda code for(y = 0; y < HEIGHT; y+=BLOCK_H) { for(x = 0; x < WIDTH; x+= BLOCK_W) { for(i = 0; i < BLOCK_H; i++) { for(j = 0; j <…
Noreen Bibi
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sum += x; sum /= y; behaves differently to temp = x; temp /= y; sum += temp

I just finished spending ~4hours debugging an issue I had with a larger program, and even after fixing it, I still can't figure out why it was causing an issue. EDIT: MAIN DIFFERENCES between the two versions. Version 1 (Wrong): for (int…
The Muffin Boy
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discrete cosine transform in matlab

In the matlab code, i apply the discrete cosine transform in an image,after applying the dct, the file size of the dct image is increased from the original file size.Is it true without applying quantization and entropy coding,the file size of the…
user15286
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DCT taking too long to be implemented

I am trying to implement DCT 2-D but as mentioned it takes too long. I have tried it on Matlab using dct2d and it is really a LOT faster. I am using dct-2D from wikipedia page: https://en.wikipedia.org/wiki/Discrete_cosine_transform Any ideas?
J.S
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