The Ridgelet and Curvelet Transforms - Sparse Image and Signal Processing - page 113

Figure 5.17. (top left) Saturn image and (top right) its histogram equalization.
(bottom left) Saturn image enhancement by the (Laplacian) sharpening method
and (bottom right) using the curvelet transform.
CurveLab is available for download (http://www.curvelet.org), and this is linked
from the topic's Web site (http://www.SparseSignalRecipes.info).
5.6.2 Sparse Representation Using DCTG2
The following MATLAB code uses WaveLab and CurveLab to illustrate how the
DCTG2 is able to sparsely represent the “Barbara” image and produces Fig. 5.18. It
also compares the DCTG2 to the undecimated wavelet transform (UWT).
% Read image;
img = fliplr(rot90(ReadImage('Barbara'),-1));
[N,J] = quadlength(img);
subplot(221);imagesc(img);axis image;axis off;colormap('gray')
set(gca,'FontSize',14);
title('(a)');