Stairstep Resize Myth Debunked
For years now, ever since a Photoshop World conference back in my juice-label days, whenever I’ve had to resize an image up — make larger file from a small original, I mean — I’ve used the “stairstep” method. I’m pretty sure it was Scott Kelby whose presentation started the trend for me, followed by another Photoshop “guru” afterwards cementing the method; others have been heard to say the same thing.
By “stairstepping,” I’m referring to the practice of sizing up an image in 10% jumps. I’ve even added actions to Photoshop to do this, so it’s just a matter of a few clicks to get an image to a size I might need. By and large, it’s worked pretty well.
Well, no longer — it’s been proven the less effective method:
Stairstep upsampling on the left; bicubic (with smoothing) on the right.
[I]t’s pretty easy to see that this method doesn’t hold a candle to the bicubic smoother method. Look at the differences in test patches 0/4, 0/5, 0/6. They’re no longer clearly resolved, because the aliasing that I feared has messed them up. The same aliasing has the effect of ‘enlarging’ each of the dark areas, so that the Stair Interpolation version seems to ‘bloom’ slightly compared to the bicubic version.
Read the rest, including some nifty mouseover comparisons, here. (And check out some of Paul’s portfolio — nice.)
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Posted by Giles, Wednesday, June 21, 2006, at 11:11 AM.
Posted to Book cover photography | Book design | Computers | Design | Photography | Technology
