Aliasing (moire patterns)
All photograph images are slightly aliased, even when not visually apparent. That is why resizing an image can cause…
When photos are resized, the new resized image can show obvious aliasing effects, as below (moire patterns). There are processing tricks to make the resized image more acceptable. All these tricks cause a loss of sharpness.
But the truth is… All photograph images are slightly aliased, even when not visually apparent. ( WOW, I didn’t know that) That is why resizing an image can cause these problems, when the details are right for amplifying the visual alias.
There is a way to capture data that is not aliased. It is used in oil field seismology. But unfortunately the technique cannot be applied to capture photographic data.
Thanks to our Science guru Brian, for these awesome facts!