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Digital photography - prevent aliasing when resampling images | Entertainment | Tech-Recipes

Started by qdideas · Hace 9 meses

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  • Mal

    Hace 4 meses

    Your method is not the best way. With going to 50% or 25% or any percentage size reduction you will get stair stepping or jaggies on diagonal lines. Try it on a photo of the telephone wires outside on the poles and you will see what I mean.

    The better way that works beautifully, as long as the resulting image is smaller that the original, is to reduce in Photoshop and change the number of pixels in just one dimension (the other dimension changes automatically). That smaller image will have a slight degree of fuzziness due to the ambiguity regarding which colors should be averaged into which new and fewer photosites/pixels. The cure for that is to apply a small degree of sharpening in Photoshop. The sharpening clears up the ambiguity and makes a decision of what should go where. It is quite effective and the image will be seamless rather than pixilated.

    Understand any time you reduce a digital image you will lose information. But the Photoshop way with a slight degree of sharpening will give results where you could not tell that the image was not shot at the smaller image size.

    Here is how to do it in Photoshop: 1. open your image in Photoshop. 2. click on the image on the taskbar at the top left. 3 you will get a drop down menu and click on the word size. A new window opens and there will be a word labeled width. Change the number of pixels in that box to your new dimension and hit OK. Open the image to full size and if it looks fine leave it alone. If you want it sharper then sharpen it.

    For instance – my camera shoots images that are 4272 in the long axis. I change that to 1024 which fits my entire screen with no overlap.
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