Introduction

Photoshop CS has introduced changes in the image upsizing routine: new options for "bicubic smoother" and "bicubic sharper". This is what Adobe says about these new options:

Bicubic Smoother will produce smoother results when enlarging an image and Bicubic Sharper will preserve more detail when you reduce an image in size. These interpolation methods will produce results as good as if not better than using what was known as the ‘step interpolation’ method, and more quickly too. (What's New in Photoshop CS - PDF extract from Photoshop CS for Photographers Amazon.com Amazon.co.uk)

I've put together some comparisons using different methods to see whether this claim is true.

Upsizing Methods

The examples have taken a 200 x 200 pixel crop and upsized to 2x and 4x using:

In some cases, I've added variations on BiSh and BiSm. I've included both unsharpened and sharpened output. The upsized images were sharpened using FocalBlade. I used the same settings of medium for sharpening, texture and details, but let FocalBlade analyse the image each time.

The images were all converted using Camera Raw so that differences in converters did not complicate the comparison. Conversions were made to 16-bit and resampling was done in 16-bit except for GF, which only works in 8-bit mode.