How do I downsize an image without introducing blur?

[anonymous]

I found this site looking for an answer to my Photoshop question. I have an image that I want to be smaller but when I downsize it, a certain edge gets blurry. If you zoom in on the edges, they're nice and clean, but when I downsize it, the edges get anti-aliased and I don't want that. How do I downsize without getting that blurred edge?

[McQ]

You can downsize without anti-aliasing by using nearest neighbor interpolation in Photoshop (or otherwise). The only drawback to this is that it is the most susceptible interpolator to moiré and other artifacts, and does not reduce noise (if any).

If you try using nearest neighbor, it retains the crisp edge, but also retains aliasing and makes the anti-aliased text look odd. You could try downsizing two versions: one with nearest neighbor, and the other as normal (bicubic usually). You could then use a layer mask and only include the edge (which you are concerned about) from the nearest neighbor downsize, while the rest of the image is from bicubic. This is perhaps the most time consuming, but will get you the result I believe you are looking for.

Another option is to sharpen afterwards using and unsharp mask with a radius of 0.2 and high percentage (and zero threshold). This can offset the softening while avoiding halo artifacts from sharpening. I would think this is the best way to proceed. Hope this all helps get you started.

[anonymous]

Thank you so much for your help. I thought I would go crazy!!

The reason why I need a clean edge is because it's for a game where the edge is eventually going to be programmed to be transparent. The last option, using two versions (bicubic and neighbor) sounds like the best plan.. I'll do that.

[sanjja]

When I downsize an image in Photoshop, I use Bicubic Sharper,which Adobe itself states is "best for reduction."

Go to image/image size. A large menu will open. Make sure the three boxes in the left bottom of the menu (Scale Styles, Constrain Proportions, and Resample Image) are checked. Pick a size, allowing for proper application -- e.g, web (72 ppi) or hard-copy print (240-360 ppi). Then open up the bottom horizontal menu and pick: Bicubic Sharper (best for reduction"). Finally, hit "OK."