Changes between Version 1 and Version 2 of Examples/Fft2dHighpass


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Timestamp:
May 7, 2010, 7:08:49 AM (15 years ago)
Author:
Ben Lippmeier
Comment:

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  • Examples/Fft2dHighpass

    v1 v2  
    11== fft2d-highpass ==
    22
    3 Applies a highpass filter to a BMP image, using a Fast Fourier Transform. The first argument is the lower cutoff frequency.
     3Applies a highpass to a BMP image. The first argument is the lower cutoff frequency.
     4
     5Each of the RGB channels is converted to the frequency domain, the lower frequencies are set to zero, then the channels are converted back to the image domain.
    46
    57{{{
    … …  
    79}}}
    810
     11=== Code ===
     12
     13The main algorithm is at http://code.haskell.org/repa/repa-stable/repa-algorithms/Data/Array/Repa/Algorithms/FFT.hs
     14
     15The wrapper is at http://code.haskell.org/repa/repa-stable/repa-examples/FFT/src/HighPass/Main.hs
    916
    1017=== Test Data ===
    11 
    12 `lena.bmp` is a standard test image. See [http://en.wikipedia.org/wiki/Lenna http://en.wikipedia.org/wiki/Lenna]
     18[http://en.wikipedia.org/wiki/Lenna http://en.wikipedia.org/wiki/Lenna] is a standard test image.
    1319
    1420|| lena.bmp || lena-high2.bmp ||
     21|| [[Image(Examples/Fft2dHighpass:lena-thumb.jpg)]] || [[Image(WikiStart:lena-high2-thumb.jpg)]] ||
     22|| [http://code.haskell.org/repa/wiki/images/lena.bmp full size] || [http://code.haskell.org/repa/wiki/images/lena-high2.bmp full size] ||
    1523
     24=== Runtime ===
     25Compiled with GHC 6.13.20100309. 512x512 image.
     26
     27Running on a Intel i7 iMac. 
     28
     29|| Threads || Time(s) ||
     30|| 1  || 24.81 ||
     31|| 2 || 13.37 ||
     32|| 3 || 10.4 ||
     33|| 4 || 7.79 ||
     34|| 5 || 8.24 ||
     35|| 6 || 7.25 ||
     36|| 7 || 6.87 ||
     37|| 8 || 6.58 ||
     38
     39