I have decided to revisit my old post about enlarging photos with Gimp vs. Photoshop and Qimage since I found out there is a better way to enlarge photos, albeit more CPU heavy, in Gimp. In my old post I enlarged photos in Gimp using Cubic interpolation but after some reserch I have found out that Sinc (Lanczos3) does a far better job when enlarging. To check this out I decided to revisit the old test and enlarge the photo once more but this time with Sinc interpolation.
As before I started out with the native resolution Sigma file and enlarged them in Gimp, Photoshop and Qimage. Lets see the results, you are looking at a small area in the print at 200% resolution or zoom in Gimp. The first photo is the one enlarged with Gimp using Sinc (Laczos3), then the Cubic in Gimp, then Photoshop and finally Qimage.
My conclusions again
Qimage still creates the best version with a cleaner, sharper and less pixalated image. But Gimp using Sinc (Laczos3) interpolation is pretty darn close. Qimage still has the edge but by so little. The final output from Gimp using Sinc looks almost identical to the Photoshop version using Bicubic smoother. Have in mind I am using PS cs2 which is a rather old program and the new Photoshop version probably has something new when it comes to enlarging. But why bother when Gimp can produce excellent result with Sinc interpolation almost rivaling the result from Qimage.
I also did a print test on photographic paper via Epson 1270 printer and from a normal viewing distance it was hard to tell them apart but there is a small difference. The Gimp and Qimage prints are very close and I see no need to use Qimage over Gimp for enlarging photos.
If you want to redo this test you can download the original Sigma file in it’s native resolution.
Now I have no longer a need to get Qimage to work on Ubuntu via Wine. It just no longer is an issue.