Best Interpolation Methods - Qimage vs Adobe - Revisited

Started Mar 27, 2014 | Discussions thread
Flat view
Ron AKA Veteran Member • Posts: 4,875
Best Interpolation Methods - Qimage vs Adobe - Revisited

Nearly 10 years ago on this forum I did a comparison of interpolation methods to increase resolution for enlargements. A lot of things have changed in the time that has passed. The resolution of cameras has increased greatly. I had a 3 MP Fuji at the time. The need for interpolation has been significantly reduced, but for larger prints it is still needed. And for Qimage new methods have been developed. So I thought it was time to revisit the issue and see where things are now. Opinions varied some, but in the original testing I ranked these as the top three methods in order:

1. Qimage Pyramid

2. Adobe Bicubic Smoother

3. Qimage Vector

When I produced the images to do the comparison I started with a 4"x5" 72 PPI original, and then down rezed it to 22 PPI and then rezed it back up again to 72 PPI with each of the 6 different methods tested. This time I thought I would do it a bit different. It is claimed that best methods for down rez are different than for up. So, to counter this I used the Adobe Bicubic Sharper, which is claimed to be best for down rez and used it to make one 22 PPI image. Then I used that same low rez image with each of the current 8 methods I tested. And this time I brought resolution up to 360 PPI instead of 72. With the image display technology that DPReview now has, that should make it easier to compare each of the images.

What were the results? They turned out to be a total surprise. I did a blind evaluation of all the images using the side by side display in the PSE Organizer. It is kind of a lame display as by default you look at the images blindly with no info on each image until you click on the "I" icon. This let me pick the best of the 8 without know which it was, and then one by one pick the next best and so on. Since the Adobe methods have not changed in 9 years or at least I assume they have not, as their name has not changed, and Qimage has developed 3 new methods with Fusion the latest, I expected Qimage Fusion to be the winner. Well no, it wasn't in my eyes. I picked the same method as I did 9 years ago - Qimage Pyramid! YMMV, and I would be interested in your opinions. There are very distinct differences in the methods. In general the sharper and clearer they are, the more artifacts they have. I find artifacts distracting, and generally picked smoothness and lack of artifacts over sharper with glaring artifacts. You may choose differently.

So here they are. First the original image at 72 PPI and then in order from in my opinion best to worst, the 8 methods each at 360 PPI.

Last place went to Adobe Nearest Neighbour. I threw that one in as an example of how bad interpolation methods can be. Jim Kasson has written a number or articles and done some similar testing. He claims Nearest Neighbour is the method used by Epson in their printer driver. If so, you certainly are well advised to stay away from letting the printer driver do that nasty stuff to your image!

Conclusion? I will switch my Qimage default interpolation method from Fusion to Pyramid, and continue to avoid Adobe... But if forced I would use Bicubic Smoother.

Original 4"x5" @ 72 PPI

Qimage Pyramid

Qimage Hybrid SE

Qimage Hybrid

Adobe Bicubic Smoother

Qimage Fusion

Adobe Bicubic

Adobe Bicubic Sharper

Adobe Nearest Neighbour

 Ron AKA's gear list:Ron AKA's gear list
Sony RX100 Epson Stylus Photo R3000 +1 more
Flat view
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow