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February 5th, 2008
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#1 (permalink) |
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Member
Join Date: Sep 2007
Location: Goteborg
Posts: 88
Name: Robert Karlsson  |
Why is the default highligh = 0,2 for "mr photographic exposure control"?
I'm not really having any problems with this, I'm just curious!
I find the "mr photographic exposure control" is quite nice and I think it does a great job making balanced renderings. However, I wonder why the highlight default is 0,2? Doesn't this mean the highlights are clamped? I mean, if the S-shaped graph is anything like a histogram, doesn't that mean that you loose detail in the brightest areas? Just a thought... Robert |
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February 7th, 2008
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#2 (permalink) | |
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Member
Join Date: May 2006
Location: Eskilstuna
Posts: 70
Name: Håkan Andersson |
Re: Why is the default highligh = 0,2 for "mr photographic exposure control"?
They aren't really clamped they are compressed.
This is what film does, also. Film as a "toe" and "knee" region, which is what this curve emulates. The default is just something "camera-ish" looking. If you set highlights to 1 and shadows to 0, you have a completely linear curve (prior to gamma correction). If you do this you will see that highlights blow out much quicker, which could be a look you may want for a "contrasty" result, but is often undesirable and very "video" looking. (Actually to make it completely "video" looking you need to add ringing to overbrights, "sharpening" they call it in video, but that's a digression). BTW: I do indeed suggest to turn on Vignetting to 4.0 as a good default. I'm a bit sad someone (that was not me) chose to default it to 0.0, since actually a real camera by nature always has some vignetting (the only way to completely remove it in a physical camera would be to have a ND filter that is darker in the center to compensate... ) According to Wikipedia the Natural Vignetting of a camera is the 4:th power of the cosine of the light angle against the film plane, and it so happens that the "vignetting" parameter is the power of the cosine of the ray angle to the film plane....  /Z Quote:
__________________
mentalraytips.blogspot.com - mr Zap Andersson - a completely mental shader guy |
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February 7th, 2008
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#4 (permalink) | |
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Member
Join Date: May 2006
Location: Eskilstuna
Posts: 70
Name: Håkan Andersson |
Re: Why is the default highligh = 0,2 for "mr photographic exposure control"?
Quote:
I have my blog, and I'll have a siggraph course (or two) this year... /Z
__________________
mentalraytips.blogspot.com - mr Zap Andersson - a completely mental shader guy |
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February 7th, 2008
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#5 (permalink) |
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Member
Join Date: Sep 2007
Location: Goteborg
Posts: 88
Name: Robert Karlsson |
Re: Why is the default highligh = 0,2 for "mr photographic exposure control"?
Great explanation! Master Zap, you're the man. I really like the way CG is moving more and more towards realworld photography - it takes much of the guesswork out of setting up the rendering. Especially used in combination with photometric lights and things like candela, lumen, and the rest (all it takes now is for me to figure out what all that means!).
I'll definitely look into vignetting now that you recommended it. Since it defaults to 0 I figured it was better left alone :-) Cheers, Robert |
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February 7th, 2008
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#6 (permalink) | |
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Senior Member
Join Date: Oct 2007
Location: Australia
Posts: 375
Name: James Burrell  |
Re: Why is the default highligh = 0,2 for "mr photographic exposure control"?
Quote:
 "have my blog," which i read often  "I'll have a siggraph course (or two) this year..." time to buy myself a plane ticket :'( |
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