DCT: Two Dimensional Discrete Cosine Transformation and Inverse...

In imagerExtra: Extra Image Processing Library Based on 'imager'

Description

DCT2D computes two dimensional discrete cosine transformation. IDCT2D computes two dimensional inverse discrete cosine transformation.

Usage

DCT2D(imormat, returnmat = FALSE)

IDCT2D(imormat, returnmat = FALSE)

Arguments

imormat	a grayscale image of class cimg or a numeric matrix
returnmat	if returnmat is TRUE, returns numeric matrix. if FALSE, returns a grayscale image of class cimg.

Value

a grayscale image of class cimg or a numeric matrix

Author(s)

Shota Ochi

References

Makhoul, J. (1980). A fast cosine transform in one and two dimensions. IEEE Transactions on Acoustics, Speech, and Signal Processing. 28 (1): 27-34.

Examples

g <- grayscale(boats)
layout(matrix(1:2, 1, 2))
plot(g, main = "Original")
gg <- DCT2D(g) %>% IDCT2D() %>% plot(main = "Transformed")
mean((g - gg)^2)

Example output

Loading required package: imager
Loading required package: magrittr

Attaching package: ‘imager’

The following object is masked from ‘package:magrittr’:

    add

The following objects are masked from ‘package:stats’:

    convolve, spectrum

The following object is masked from ‘package:graphics’:

    frame

The following object is masked from ‘package:base’:

    save.image

[1] 2.665872e-32

imagerExtra documentation built on May 2, 2019, 1:44 p.m.