kwalsh Offline Upload & Sell: Off
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denoir wrote:
Preserving the information about the dotted pattern is a good argument for no AA filter. The color artifacts you can get rid of in PP in most situations but there is no way of reconstructing information you have thrown away.
You can recreate any sort of false data you want or remove any false data you want anywhere in the image. Whether you want to be desaturating portions of the image to deal with color moire or start adding detail or sharpening to regions is up to the photographer. In some cases one is harder than the other or more frequently necessary than the other. I think this was already covered pretty thoroughly.
That said, I have already agreed with you that in many cases the false information looks nice. In others, to my taste (and others) it looks like crunchy garbage. That was my main point here. Leave it at that - sometimes good for some, sometimes bad for others.
And actually, now that you mention it, the wild rainbow of colors is indeed a good argument for no AA filter. That was shot with a camera that has an AA filter. I mean, why bother? You've killed off detail with it and you still get the moire.
Silly point. You get global color issues in more situations without the AA than you do with. It is a trade off as to what you shoot and what post-processing you want to deal with. Again, sometimes useful sometimes not.
Err.. I have no idea what you are talking about. I don't recall saying any such thing nor have I been able to find any such statement by anyone in the past pages and definitely not any made by me.
This post:
https://www.fredmiranda.com/forum/topic/1038448/14#9874135
Specifically this quote:
Color moire occurs when you have a lens that resolves detail higher than the nyquist frequency at very high MTF and it's a high contrast, high frequency subject and you get an unfortunate alignment with the CFA. An AA filter smears the light across the CFA quadruplets (GRGB). Without an AA filter and with the conditions I mentioned above you can get for instance that GRG records black (zero signal) while B gets a full blast of white. A perfectly AA filtered sensor would in the case of such an edge record G=0.5, R=0.5, G=0.5, B=0.5. In the case without the filter you get G=0, R=0, G=0, B=1. Then during raw development the demosaicing algorithm calculates a linear combination of the colors for each of the four pixels and ends up with something blue.
That's the basic mechanism. The point however is that this is at the local pixel level and the color artifacts you see are a few grouped pixels with wildly varying colors. You can't get a color shift from it. It just looks like very high frequency colored noise.
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You appear to state color effects are only on a local pixel level and can not be seen as color shifts on a more global scale. That's not true. Apologies if I misread or misunderstood what you wrote there.
Ken, I'm disappointed in you. I thought we had agreed to skip this type of cheap personal attacks.
It wasn't meant as a personal attack! Apologies if it came off that way, "credibility" was probably not the appropriate word.
I just meant it reads a bit silly when you completely ignore the OP's point about obvious and gross color artifacts to make the same point about pleasing false detail you've already expressed repeatably in the thread. I think we know where you are coming from on that, and I agree with you that in some cases it is useful. Really though, reviving a dead thread and avoiding commenting on the most recent information in it only to rehash a point already beat to death didn't seem to be adding much to the discussion.
That said I probably added even less and should have just left it to scroll off the front page again...
Ken
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