In scipy why doesn't idct(dct(a)) equal to a?
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00:00 Question
01:14 Accepted answer (Score 13)
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https://stackoverflow.com/questions/3489...
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#python #scipy #dct
#avk47
--
Music by Eric Matyas
https://www.soundimage.org
Track title: Magical Minnie Puzzles
--
Chapters
00:00 Question
01:14 Accepted answer (Score 13)
01:39 Thank you
--
Full question
https://stackoverflow.com/questions/3489...
--
Content licensed under CC BY-SA
https://meta.stackexchange.com/help/lice...
--
Tags
#python #scipy #dct
#avk47
ACCEPTED ANSWER
Score 13
You need to set scaling to ortho for both dct2 and idct2:
def dct2 (block):
return dct(dct(block.T, norm = 'ortho').T, norm = 'ortho')
also, you cannot expect the values to be exactly the same, but almost the same within some margin of error:
np.allclose (a, idct2(dct2(a)))