Specifications

Linear Image Transforms
7-1
7
This chapter describes the linear image transforms implemented in the
library: Fast Fourier Transform (FFT) and Discrete Cosine Transform
(DCT). Table 7-1 lists the functions performing linear image transform
operations.
Table 7-1 Linear Image Transform Functions
Group Function Name Description
Fast Fourier
Transform (FFT)
iplRealFft2D
Computes the forward or inverse 2D
FFT of an image.
iplCcsFft2D
Computes the forward or inverse 2D
FFT of an image in a complex-
conjugate format.
iplMpyRCPack2D
Multiplies data in the RCPack format.
Discrete Cosine
Transform (DCT)
iplDCT2D
Computes the forward or inverse 2D
DCT of an image.
Fast Fourier Transform
This section describes the functions that implement the forward and inverse
Fast Fourier Transform (FFT) on the 2-dimensional (2D) image data.
Real-Complex Packed (RCPack2D) Format
The FFT of any real 2D signal, in particular, the FFT of an image is
conjugate-symmetric. Therefore, it can be fully specified by storing only
half the output data. A special format called
RCPack2D is provided for this
purpose.