No. Because these kinds of lens flares usually make a sound when seen on TV.
For example, the hero smiles and you see and hear the ding on his teeth.
Knowwhatimean?

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Chris Huff wrote:

> 
> Or are you talking about an automatic thing that goes through the image
> looking for the darkest and brightest pixels, and adjusts the image so
> those pixels are black and white? That could be done...

Almost. The Photoshop filter is a bit more complex but I think all those
features would be cumbersome in POV. In Photoshop you can adjust the settings
according to a colour histogram while seeing the preview image. 

"Auto Levels" in Photoshop adjusts each channel so that the reddest gets a 255
red value, the greenest a 255 green, etc. This is not very reliable and more
often than not produces an unwanted tint. 

I suggest the following syntax:

levels { <dark_tint>, <bright_tint> }

If the brightest was <.9,.95,.93> the new value would be:
<.9,.95,.93>/.95*bright_tint

For most "real world" scenes, levels{1,1} would then give good results. I have
to do this manually in Photoshop, adjusting the endpoints to the histogram
endpoints.

The in-between values could be changed as a linear function between the two new
endpoints. In Photoshop there's a value which controls this function, but I'm
not sure how it works. It seems to use a power function taking values from 0 to
10 where "1" is linear, 1-10 sort of moves the pure red/green/blue to pixels
which previously were dark. 1-0 moves the palettes against the light area
making the whole image darker. Aw, I'm hopeless at explaining. I could post
some demo images if you're interested.

sig.

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TonyB wrote:
> 
> Look into adding some way of adding sparkles when the color of the pixel
> surpasses a user-specified threshold.

John Beale has done sparkl01 which "add sparkle glint-type effects to a
TGA image"
http://www.best.com/~beale/gforge/

-----------------------------------------------------------------------
Kari Kivisalo                                          www.kivisalo.net

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Chris Huff wrote:
> This sounds like the "highlight/midtone/shadow level adjustment" filter
> which is still in the "to-do" list. I would like to make a filter which

Catching up on the other threads here I found that you've already mentioned
this. Levels wouldn't be the same as highlight/midtone/shadow because it's
dynamic; it changes according to the darkest/brightest pixel. The
highlight/midtone/shadow will change the colour values regardless of the image.
I think this could make the levels process very useful since we don't have the
fast preview capabilites of image editing programs.

sig.

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On Fri, 28 Apr 2000 09:13:10 -0400, "TonyB"
<ben### [at] panamac-comnet> wrote:

>No. Because these kinds of lens flares usually make a sound when seen on TV.
>For example, the hero smiles and you see and hear the ding on his teeth.
>Knowwhatimean?

I understand now. Perhaps "glint" is a better word for what you are
describing.

Later,
Glen Berry


( Remove the "7" from 7no### [at] ezwvcom to email me. )

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In article <390A074A.1A022398@kivisalo.net>, Kari Kivisalo 
<kar### [at] kivisalonet> wrote:

> John Beale has done sparkl01 which "add sparkle glint-type effects to a
> TGA image"
> http://www.best.com/~beale/gforge/

I downloaded the source and will have a look at it. I already have a 
kind of sparkle effect working, but this could be helpful.

-- 
Christopher James Huff - Personal e-mail: chr### [at] yahoocom
TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
Personal Web page: http://chrishuff.dhs.org/
TAG Web page: http://tag.povray.org/

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In article <390A0B46.AEDCEB12@stud.ntnu.no>, Sigmund Kyrre Aas 
<as### [at] studntnuno> wrote:

> Catching up on the other threads here I found that you've already 
> mentioned this. Levels wouldn't be the same as 
> highlight/midtone/shadow because it's dynamic; it changes according 
> to the darkest/brightest pixel. The highlight/midtone/shadow will 
> change the colour values regardless of the image.
> I think this could make the levels process very useful since we don't 
> have the fast preview capabilites of image editing programs.

How about a filter that can take either 2 or 4 colors, if 2 colors, then 
it would adjust the colors of the image so the brightest is equal to the 
second color and the dimmest equal to the first. If 4 colors, it would 
override that "auto adjust" and adjust the image as if the two 
additional colors are the dimmest and brightest colors.
Is this what you want?

-- 
Christopher James Huff - Personal e-mail: chr### [at] yahoocom
TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
Personal Web page: http://chrishuff.dhs.org/
TAG Web page: http://tag.povray.org/

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On Sat, 29 Apr 2000 10:56:20 -0500, Chris Huff
<chr### [at] yahoocom> wrote:

>In article <390A0B46.AEDCEB12@stud.ntnu.no>, Sigmund Kyrre Aas 
><as### [at] studntnuno> wrote:
>
>> Catching up on the other threads here I found that you've already 
>> mentioned this. Levels wouldn't be the same as 
>> highlight/midtone/shadow because it's dynamic; it changes according 
>> to the darkest/brightest pixel. The highlight/midtone/shadow will 
>> change the colour values regardless of the image.

You are only considering "auto levels" when you make that statement
about the levels control, if you are refering to the levels control as
implemented in Photoshop. It is also possible to supply parameters to
the levels dialog box to control the black point, white point, and
midpoint value (The midpoint value is similar to gamma, if not indeed
an actual gamma setting.) You can indeed manipulate the image in a
predermined manner, without relying on the computer to make some sort
of dynamic or automatic adjustment.

The GIMP has "levels" control, both auto and manual. It also seems to
be on par with the Photoshop levels control. Since the source is
available for the GIMP, it might pay to research the method used in
this program for inspiration.

PSP also has a similar function (histogram stretching? histogram
equalization?, not sure...), but it is different, and yields inferior
results.


Later,
Glen Berry

( Remove the "7" from 7no### [at] ezwvcom to email me. )

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Chris Huff wrote:
> 
> How about a filter that can take either 2 or 4 colors, if 2 colors, then
> it would adjust the colors of the image so the brightest is equal to the
> second color and the dimmest equal to the first.

Problem is you don't know the hue of the brightest/darkest pixel. That's why
I'm suggesting the bright/dark_tint. If the [darkest, brightest] colour is
[<.05,.1,.15>,<.9,.95,1>] and you simply set them to [<0,0,.05>,<1,.95,1>] it
will scale the rgb values differently. Although this might be useful, it will
almost certainly produce a tinted image.

"Auto Levels" in Photoshop does not preserve the hues of the darkest/brightest
pixel. It takes each colour component and scales them seperately, producing
[darkest, brightest] = [0,1], which IMHO is no good.

To get both these capabilities you could add keywords such as "absolute" and
"relative".

levels{ <dark>, <bright> relative}
If the brightest is <.9,.95,.93> the new value will be:
<.9,.95,.93>/.95*bright

If the darkest is <.1,.2,.3> the new value will be:
<0,.2,.3>*(1-.1)*dark
(Not sure of the math here. Idea is that 0.1->0 represents a 10% brightness
change)


levels{ <dark>, <bright> absolute}
If the brightest is <.9,.95,.93> the new value will be:
bright

If the darkest is <.1,.2,.3> the new value will be:
dark


sig.

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I think I get what you are saying...instead of adjusting the rgb values 
directly, you want to adjust the brightness of the colors?

-- 
Christopher James Huff - Personal e-mail: chr### [at] yahoocom
TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
Personal Web page: http://chrishuff.dhs.org/
TAG Web page: http://tag.povray.org/

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