I have done an implementation of this paper from CG&A for image reconstruction.

Original and a greyscale from CIE luminance

8x magnification - greyscale

8x scale using gimp

DDT method (8 passes using yms optimisation)

8x magnification - colour

8x scale using gimp

DDT method (8 passes using yms optimisation)

DDT method (3 passes using yms optimisation)

Photo from a recent shuttle mission

original photo

zoomed section original

4x magnification using gimp

DDT method (8 passes using yms optimisation

A simple example

Original

My implementation

Gimp version

Another edge-directed algorithm on the same image

Index of /ddt 
Icon  Name                    Last modified      Size  Description
[DIR] Parent Directory                             -   
[IMG] costfunc.png            31-May-2002 00:10  3.4K  
[IMG] flow.png                10-Jun-2002 00:35   53K  
[IMG] flowerg-gimp.png        26-Jun-2002 00:53   50K  
[IMG] flowerg.png             10-Jun-2002 00:35  8.9K  
[   ] imagefilt-rob.tar.gz    06-Jan-2003 16:57   37K  
[IMG] lisa-gimp8.png          08-Jun-2002 17:51  310K  
[IMG] lisa-gimp8c.png         08-Jun-2002 17:32  710K  
[IMG] lisa-scale10.png        08-Jun-2002 17:32  762K  
[IMG] lisa-scale11.png        08-Jun-2002 17:46  763K  
[IMG] lisa-scale12.png        08-Jun-2002 17:48   19K  
[IMG] lisa-scale14.png        08-Jun-2002 18:16  349K  
[IMG] lisa-scale4.png         08-Jun-2002 15:13   62K  
[IMG] lisa-scale5.png         08-Jun-2002 15:14  415K  
[IMG] lisa-scale7.png         08-Jun-2002 16:03  398K  
[IMG] lisa.png                08-Jun-2002 15:14   34K  
[IMG] s110-zoom-ddt.png       08-Jun-2002 18:48  2.1M  
[IMG] s110-zoom-gimp4.png     08-Jun-2002 18:50  1.8M  
[IMG] s110-zoom.png           08-Jun-2002 18:50  247K  
[IMG] s110e5004.jpg           08-Jun-2002 18:52  1.4M  
[DIR] t/                      30-Mar-2010 23:10    -   
[IMG] thigh.png               12-Jun-2002 14:39  306K  
[IMG] thigh2.png              12-Jun-2002 14:40  284K  
[TXT] truck-distance-8pass..> 11-Jun-2002 10:13  681   
[TXT] truck-distance-8pass..> 11-Jun-2002 10:13  340   
[TXT] truck-yms-8pass.txt     11-Jun-2002 10:13  340   
[IMG] truck.png               11-Jun-2002 10:30  224K