the ippiResize function will be deprecated in future releases. We recommend you to use ippiResizeSqrPixel function which do support lanczos interpolation.
I've tried theippiResizeSqrPixelfunction instead ofippiResize, adding a tmpbuf and zeros for the shift values.
I can see that this enables theCUBIC2P interpolations that the older function did not support, but the Lanczos image still comes out with unsatisfying quality, just as I've shown in my previous post: The picture is about the same as the one I get fromIPPI_INTER_CUBIC.
Could you please provide your test case and source image, so we can look carefully if everything is ok with how you call the function?
I tried out the example provided in Vol2 of the IPP manual and found that it all works as intended by Intel: I get the results as described. So there's no reason to suspect I'm calling it in a wrong way. Plus, the parameters are straight-forward, what can be done wrong there that would lead to sensible results that just provide unsatisfying interpolation results? The code I have here is woven into quite a complex app, and unless you can hint at possible errors I could make, I find it a waste of time to turn it into a demo app that I can send you to try it out yourself - please don't take offense at that.
It's rather obvious to me that the Lanczos algo used by the Resize functions is the culprit here - it apears inferior to the one Apple provides in their vImage lib. Theirs provides a great result where there are hardly any interference patterns where Intel's shows them pretty badly, as shown in the sample images I linked to in my first post.
If I scale that down to any factor < 1 (same factor for X and Y), using Lanczos, I see the interference patterns. If I let my browser (Safari 3 on OSX) or Apple's vImage scaler make it smaller, those patterns hardly show, just as it's expected from a Lanczos filter. Are you sure you'd be able to get similar good results with IPP's resize function? Are there any examples to look at?
(I'd like to send you some confidential infos, that I don't want to post publically, but I cannot figure out how to do that here)