Check your Preferences setting for the Image Interpolation field in Preferences > General > Image Interpolation.

I've changed back to Bicubic myself.  I could never see the reasons for using those others.

What "part of it" is left to be solved?

-Noel

''Bicubic Sharper'' just does that.  Adobe's ideas of ''best for downsampling'' and mine just differ.  Have you used 'Bicubic Sharper'' before?

''Bicubic'' is what Photoshop has always defaulted to up to now.

Make your default ''Bicubic Smoother'' to completely avoid any sharpening (which by the way there seems to be just a little of in just plain ''Bicubic'' as well). 

-Noel

I don't think it's making any choices, except to use Bicubic Sharper for downsampling and Bicubic Smoother for upsampling.

I'm thinking of doing some comparisons...  I'll see if I can find a good image for showing the differences.

-Noel

Okay, I did some comparisons of the various forms of downsampling. What I did was find a representative image with some good contrasts, then downsample to 25% using the various methods in Photoshop CS5 and CS6, then re-upsample to original size using Nearest Neighbor, so we can clearly see the pixels. Here are the results:

Photoshop CS5:

Photoshop CS6:

Based on these, I'd say there's actually some USM sharpening in Bicubic Smoother as well, more than just plain Bicubic!

Seems pretty obvious to me that just plain Bicubic is still the best, but to each his own!

-Noel

I find that the results from using CS6 Auto is a bit too "crunchy" when downsampling to perhaps only 25% of the original size (as you might do for Web display purposes).

Also there is usually some considerable darkening/clogging of the mid-tones when you downsample and it would be great if a correction for that could be built-in to the resampling algorithm.

Chris Cox wrote:

 

It's not the same math as LR, but similar in concept.

Thanks for the confirmation...

As far as Sharper/Smoother, these variants were created specifically to address the problems with resampling up or down. Yes, Sharper has a sharpening component, but it's not really useful for upsampling as Bicubic Sharper will introduce sharpening artifacts that preclude other post upsampling sharpening–which must be done separately from the upsampling to get optimal results. Yes, on the "surface' some might see useful results with upsampling but it's not as good as applying post upsample image sharpening. This isn't hard to prove...see this article The Art of the Up-Res from Digital Photo Pro magazine (and yes, I wrote that article a while ago, but it still is applicable now)

I agree with Noel.

Unfortunately both recommended down-sampling methods in CS6 (Bicubic Sharper and the new Auto) do over-sharpen for most kinds of subject matter.

It really would be better if the degree of sharpening in both algorithms could be toned down a bit so that the User can then add further Output Sharpening or local sharpening at their own discretion.

One thing I did not realize (noticed this when testing out Bicubic Automatic) is if you use one interpolation method when resizing a Smart Object. Then return to another. Then Edit Contents of that SO, Photoshop will re-render the scaled SO with the current interpolation method, even if you did not additional scaling to the SO.

Yes, that is what I thought too.

It was unexpected, but probably makes sense that any edit to SO contents would have to be re-rendered and would use the currently chosen interpolation.