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From: clipka
Subject: gamma tutorial on Wiki
Date: 26 Mar 2010 17:04:29
Message: <4bad215d$1@news.povray.org>
After a long break, I have started again working on a gamma tutorial on 
the Wiki; see:

http://wiki.povray.org/content/User:Clipka/Gamma

Comments appreciated.


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From: Jim Holsenback
Subject: Re: gamma tutorial on Wiki
Date: 26 Mar 2010 18:15:46
Message: <4bad3212$1@news.povray.org>
On Fri, 26 Mar 2010 22:04:24 +0100, clipka wrote:

> After a long break, I have started again working on a gamma tutorial on
> the Wiki; see:
> 
> http://wiki.povray.org/content/User:Clipka/Gamma
> 
> Comments appreciated.

I've not had a chance to read through all of it, but first 
impressions ... well laid out, and thorough! Nice job! I'm thinking that 
perhaps I should find an appropriate place in the docs to add a link to 
it, or at the very least a link to it in KB namespace ... would you be 
open to doing something similar (documenting) all the fine work you've 
done with radiosity as well?

Jim


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From: clipka
Subject: Re: gamma tutorial on Wiki
Date: 26 Mar 2010 21:01:14
Message: <4bad58da@news.povray.org>
Jim Holsenback schrieb:

> I've not had a chance to read through all of it, but first 
> impressions ... well laid out, and thorough! Nice job! I'm thinking that 
> perhaps I should find an appropriate place in the docs to add a link to 
> it, or at the very least a link to it in KB namespace ... would you be 
> open to doing something similar (documenting) all the fine work you've 
> done with radiosity as well?

Well, the gamma tutorial isn't finished yet - the most crucial part 
("Getting The Render Preview Right") is still missing. And then there's 
still some programming to do...

Let's put it this way: I'm generally open to the idea, but I can't 
promise anything at present; so if anyone else would volunteer you'd 
better not stop them.


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From: Warp
Subject: Re: gamma tutorial on Wiki
Date: 27 Mar 2010 02:35:04
Message: <4bada718@news.povray.org>
clipka <ano### [at] anonymousorg> wrote:
> http://wiki.povray.org/content/User:Clipka/Gamma

> Comments appreciated.

  percieved -> perceived

  While the information is great, I'm wondering if it's a bit too long-winded.
People get bored when reading a wall of text, which may be especially bad if
the important info (ie. the info which would be most useful for the reader)
is at the end. Most people might stop reading before they get to the info that
they need to know.

  Maybe some restructuring of the article could help this. After a short
introduction, first explain *what* has to be done, and then explain *why*
(rather than the other way around). Even if the reader gets bored at the
middle of the article, at least he will have seen what he needs to do in
order to get things right, even if he still doesn't know exactly why. He
can later refer to the reasons.

  Some brief history of why gamma correction exists in the first place
(going all the way back to the invention of CRT) and where the name "gamma"
comes from could be an interesting tidbit of information. This doesn't need
to be long. One single paragraph should be enough.

-- 
                                                          - Warp


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From: Warp
Subject: Re: gamma tutorial on Wiki
Date: 27 Mar 2010 02:36:14
Message: <4bada75e@news.povray.org>
Oh, and forgot to mention: The reflecting-sphere-on-checkered-plane shows
that something might be wrong with the output of POV-Ray 3.6, but it doesn't
explain why. It might be a good idea to explain what's going on with that
image and why it's wrong.

-- 
                                                          - Warp


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From: Thomas de Groot
Subject: Re: gamma tutorial on Wiki
Date: 27 Mar 2010 04:22:47
Message: <4badc057$1@news.povray.org>
I think this looks and feels very good.

While - to some extent - I agree with Warp, I believe the structure of the 
text should remain as Clipka wrote it. After all, one can jump directly to 
the practical part if one wants to.

To make that easier, I suggest to subdivide the text in 2 clear parts, 
Theory and Practice, also mirrored (of course) in the Content, and increase 
the number of code examples in the Practice part.

Thomas


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From: Kenneth
Subject: Re: gamma tutorial on Wiki
Date: 27 Mar 2010 15:15:00
Message: <web.4bae58b8661cde4765f302820@news.povray.org>
My own small 2-cents worth:

I kind of agree with Warp--the essay pretty much jumps right in with a rather
technical discussion.  A GOOD one, of course--very well done!--but it needs a
short preamble, IMO, to get folks up to speed on what gamma is basically about
(as pertaining to *images*, which is what most of us first become concerned with
when doing CGI.) Perhaps something simple about how gamma basically bends the
color/grayscale values of an image, while leaving pure black and pure white
untouched. *Then* getting deeper into the technical aspects of CRT/LCD
reproduction, etc. I agree that part of the first paragraph, "...regarding how
intermediate brightness levels between 0% and 100% are interpreted," pretty much
says it all; but it doesn't quite grab me, or give an immediate picture in my
mind of how it basically affects images.

The best advice I ever heard about writing in general was, "Grab 'em right from
the start! Make it simple! Then they'll stick around for the details."

Ken


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From: Kenneth
Subject: Re: gamma tutorial on Wiki
Date: 27 Mar 2010 15:25:01
Message: <web.4bae5ab8661cde4765f302820@news.povray.org>
Oh, and I forgot to nit-pic  :-p   (My apologies if this isn't the right place
to do so.)

PERCIEVE is spelled PERCEIVE. I wouldn't normally mention it, but the word is
used throughout the text.

KW


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From: clipka
Subject: Re: gamma tutorial on Wiki
Date: 27 Mar 2010 15:31:08
Message: <4bae5cfc@news.povray.org>
Warp schrieb:

>   Some brief history of why gamma correction exists in the first place
> (going all the way back to the invention of CRT) and where the name "gamma"
> comes from could be an interesting tidbit of information. This doesn't need
> to be long. One single paragraph should be enough.

Um... that information is in there already... so you got bored, hm? ;-)


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From: clipka
Subject: Re: gamma tutorial on Wiki
Date: 27 Mar 2010 16:41:32
Message: <4bae6d7c@news.povray.org>
Thomas de Groot schrieb:

> I think this looks and feels very good.

Thank you (and all others so far) for the feedback.

> While - to some extent - I agree with Warp, I believe the structure of the 
> text should remain as Clipka wrote it. After all, one can jump directly to 
> the practical part if one wants to.

Yes, I'll probably stick to this structure, despite unexpectedly 
numerous comments that suggest to change it.

While I do see the benefits of structuring it the other way round, there 
is a pretty simple some reason why I didn't: The order I used is simply 
my style of writing. I'd probably have a much harder time trying to get 
it the other way round and still be happy with the text.

Once I hand over the text to the POV-Ray community, everyone who feels 
up to it is free to propose a re-structured version of the text. No 
problem there.

I don't think this is really needed though. For the average user, the 
how-tos important to them probably boil down to (a) how to properly 
calibrate the system and set the Display_Gamma option, and (b) the 
advice to stay with POV-Ray's default settings and let the recently 
implemented gamma handling automatisms do their job. (a) is best placed 
(or at least linked to) in the installation section anyway, and (b) does 
not need an elaborate tutorial. For any issues beyond that, I guess the 
user will need at least some background information so that they can 
assess which of the tips are applicable to their particular problem. And 
if they already have that information, they can just skip to the how-tos 
by virtue of the table of contents. I think the section titles are 
talktive enough for that.

> To make that easier, I suggest to subdivide the text in 2 clear parts, 
> Theory and Practice, also mirrored (of course) in the Content, and increase 
> the number of code examples in the Practice part.

I guess I'd make that 3 parts: One "what is gamma all about" section 
giving background information, one "why should I bother" section naming 
some pitfalls, and one "how to" section describing how to deal with 
those issues.

I'm reluctant to already put this subdivision into place though; the 
current lower-level titles' typography makes me uneasy, them being much 
bolder and prominent than normal section titles. Looks like they're 
currently not intended to be used.


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