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Author Topic: A short illustration to aliasing and fake detail  (Read 1191 times)

ErikKaffehr

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A short illustration to aliasing and fake detail
« on: April 28, 2013, 04:12:04 PM »

Hi,

Here is a short article illustrating some aspects of aliasing and fake detail:
http://echophoto.dnsalias.net/ekr/index.php/photoarticles/75-aliasing-and-fake-detail

Best regards
Erik Kaffehr

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What is vision anyway?
« Reply #1 on: April 28, 2013, 04:54:00 PM »

Vision is nothing more than an interpretation of light. When you get down into the nitty gritty of it, even white & black are, in some sense, fake. There's nothing inherently "white" about large collections of photons or "black" about meager collections. Color is even more fake. There's somewhat of a connection between particular wavelengths of light (or photon probability distribution curves, if you prefer the particle-oriented view) and perceived colors, but color itself is not a property of light. Nor of objects...we don't see objects, only light emitted by objects. (There's no such thing as reflection either, but that's getting quite off-topic.) White, black, shades of grey & colors exist only between our ears.

So I guess fake aliasing "detail" just doesn't bother me much. If I don't know it's there, why should I care? Now when it has larger-scale effect, as in moire, then I prefer to minimize or even get rid of it. But that's just me insisting that photos conform to the way I expect them to look.

-Dave-
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BartvanderWolf

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Re: What is vision anyway?
« Reply #2 on: April 28, 2013, 06:50:26 PM »

Vision is nothing more than an interpretation of light. When you get down into the nitty gritty of it, even white & black are, in some sense, fake.

Hi Dave,

But the aliasing effects that Erik used as an example are not 'vision' (as a naming convention) induced, but rather stem from discrete sampling, and are very much predictable. Up to a certain degree they are also avoidable, if one understands the principles that cause them. Low-pass filtering (or over-sampling) is the key.

Cheers,
Bart
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== If you do what you did, you'll get what you got. ==

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Re: What is vision anyway?
« Reply #3 on: April 29, 2013, 02:05:58 PM »

But the aliasing effects that Erik used as an example are not 'vision' (as a naming convention) induced, but rather stem from discrete sampling, and are very much predictable. Up to a certain degree they are also avoidable, if one understands the principles that cause them. Low-pass filtering (or over-sampling) is the key.

Bart, yeah, I understand what Erik is getting at. I'm just questioning whether or not such small-scale effects are worth avoiding. This is why I mentioned moire (I wish LL recognized my iPad's alternate "e" characters so I could use the proper accent symbol), an example of a larger-scale effect I do seek to avoid or at least minimize.

I also find it odd that folks tend to be concerned with artifacts when they concern spatial detail but much less so when it comes to demosaicing-induced tonality issues. Personally the latter don't bother me much either, but it seems logical that both would be of equal concern to people who enjoy getting deep into the weeds of this stuff.

-Dave- (who, despite knowing that his hands are mostly empty space, still uses them for typing)   :D
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Perception
« Reply #4 on: April 29, 2013, 02:24:54 PM »

A very nice piece on perception, maybe only tangentially related to the current topic but worthy of consideration anyway:

http://opinionator.blogs.nytimes.com/2013/04/28/borges-and-the-paradox-of-the-seenk

-Dave-
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ErikKaffehr

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Re: Perception
« Reply #5 on: April 29, 2013, 03:47:24 PM »

Hi,

A long article, certainly food for thought.

Best regards
Erik

A very nice piece on perception, maybe only tangentially related to the current topic but worthy of consideration anyway:

http://opinionator.blogs.nytimes.com/2013/04/28/borges-and-the-paradox-of-the-seenk

-Dave-
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