| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Codec.Picture.Jpg.Internal.FastIdct
Description
Module providing a fast implementation of IDCT
inverse two dimensional DCT, Chen-Wang algorithm (cf. IEEE ASSP-32, pp. 803-816, Aug. 1984) 32-bit integer arithmetic (8 bit coefficients) 11 mults, 29 adds per DCT sE, 18.8.91
coefficients extended to 12 bit for IEEE1180-1990 compliance sE, 2.1.94
this code assumes >> to be a two's-complement arithmetic right shift: (-2)>>1 == -1 , (-3)>>1 == -2
Synopsis
- type MutableMacroBlock s a = STVector s a
- fastIdct :: MutableMacroBlock s Int16 -> ST s (MutableMacroBlock s Int16)
- mutableLevelShift :: MutableMacroBlock s Int16 -> ST s (MutableMacroBlock s Int16)
- createEmptyMutableMacroBlock :: (Storable a, Num a) => ST s (MutableMacroBlock s a)
Documentation
type MutableMacroBlock s a = STVector s a Source #
Macroblock that can be transformed.
fastIdct :: MutableMacroBlock s Int16 -> ST s (MutableMacroBlock s Int16) Source #
Algorithm to call to perform an IDCT, return the same block that the one given as input.
mutableLevelShift :: MutableMacroBlock s Int16 -> ST s (MutableMacroBlock s Int16) Source #
Perform a Jpeg level shift in a mutable fashion.
createEmptyMutableMacroBlock :: (Storable a, Num a) => ST s (MutableMacroBlock s a) Source #
Create a new macroblock with the good array size