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I am new to FFT, DCT and the like. Recently I was looking into the documentation for the vDSP library from Apple and was unable to find a DCT implementation. I was wondering if anyone knows of a way to calculate the DCT using one of the FFT functions provided in vDSP?

A bit of context. I am building an image processing implementation from a graphics paper I've been reading. They mentioned using DCT after performing some image sampling.

I'd really like to take advantage of the vDSP speed if at all possible.

damnabit
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  • I;m actually looking into exactly the same thing, for 1D transitions. I thought I had it figured out, but my results seem off-compared to other methods. So I need to do a bit more research. When I figure it out, I'll post it! (for the 1D case anyways). – Claude Mar 20 '12 at 12:01

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OK, turns out my results were off because I was using floats in stead of doubles....

So I managed to do 1D DCT on iOS on the vDSP. I'm not sure if it's the right way, but it gives me the same results as jtransform, which is good enough for me :).

And I know this question was old, but it might just help someone else searching for this.

https://gist.github.com/2140473

Claude
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