7 votes

Relationship between spatial frequency of an image and Aliasing

Like in any other kind of signal processing, the relationship is Nyquist's theorem. An image is a discrete sequence of samples of a continuous signal. If the original signal has frequency components ...
Dan Hulme's user avatar
  • 6,810
5 votes
Accepted

Why isn't PNG preferred over JPG for being lossless art quality yet?

I don't know if this is the real reason, but here's one possibility: because it's unnecessary. It's easy to say "JPEG = lossy = bad", but JPEG doesn't just destroy image quality willy-nilly. What the ...
Dan Hulme's user avatar
  • 6,810
4 votes

Why isn't PNG preferred over JPG for being lossless art quality yet?

Lossy does not necessarily imply any major quality loss. It is mostly dropping out meaningless information of the image in favor a much smaller image file. The amount of quality drop can be adjusted, ...
joojaa's user avatar
  • 8,437
2 votes

Is it possible to get recording device from meta data?

There's a tool called ExifTool that can extract various forms of metadata from video and audio files. Here is an example (from 2013) of using the tool on a .mov file from an iPhone, which includes ...
Nathan Reed's user avatar
2 votes
Accepted

How to change a picture to fail comparison algorithms?

It's dependent on the algorithm used for comparison, but if you have access to that algorithm, you can add small amounts of noise to pixels randomly until it misclassifies the image. If you had ...
Alan Wolfe's user avatar
  • 7,801
1 vote

Image regeneration with nearest neighbor search

I would have done it with a script and NETPBM like so: 1) reducing Image1 (the tiles) to size X by X -> Image1R 2) recording the mapping from pixel values of Image1R to coordinates (no need to ...
Leo B.'s user avatar
  • 141

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