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Originally Posted by Steve D.
Tim,
The moire effect is common with digital screen shots.
-Steve D.
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To avoid the moire efects, you'd need to photograph the TV screen at a much higher resolution. High enough that you actually capture all the RGB phosper dots. This also applies to scanners used to scan magazine ads. High enough resolution to capture individual halftone dots. Then using Photoshop or such, do a low pass filter, aka "blur" on the picture. Then shrink the image to the desired final size. Photoshop's shrink is usually preconfigured to do the blur before the shrink for you.
TV camera designers even in the old days had to worry about this. To avoid moire flicker (in interlace mode this really sticks out) they had the TV camera lens designed so it could never make too sharp an image on the pickup tube. The scan lines did a "digital sampling" of sorts of the image in the vertical direction. Have the image too sharp of say a distant window with venitian blinds and some of the slats would fall between the scan lines. And produce moire patterns that don't exist in the real world in person.