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Posted by Rick Merrill on 04/07/07 13:05
Gene E. Bloch wrote:
> "AnthonyR." <nospam@sorryspammers.com> wrote in
> news:46152706.3000301@sorryspammers.com:
>
>> Richard Amirault wrote:
>>> "Gene E. Bloch" wrote ...
>>>> I would be willing to bet (OK, maybe only a nickel) that your
>>>> camcorder has custom white balance, but I'm too lazy right now
>>>> to download the manual and find out for myself.
>>>>
>>>> Although that's not called manual, it does give a comparable
>>>> capability.
>>> I have a Sony Digital 8 that *only* has automatic color balance.
>>> My Sony Mini-DV has adjustable white balance.
>>>
>>> For the original poster ... What kind of circumstances are you
>>> shootiing? What is the color of the subject? What is the color of
>>> the background? What kind of room? Daytime? Nighttime? Windows?
>>> Are the lightbulbs all the same type (mixed incandesant /
>>> flourescant?)
>>>
>> Richard, when you say the camera has automatic white balance, what
>> do you mean? How does it balance it? How do you tell it what is
>> white? And if it's automatic, how does it do it?
>> Usually, every camera I've ever owned even the cheapest, let's you
>> point to a white object and hit a button so it can adjust to that
>> being white.
>>
>> Does your manual in the Sony Digital 8 explain how it can possible
>> determine a white subject on it's own (automatically)?
>> It might have settings for daylight, tungsten, florescent etc...I
>> can understand that, but auto, how?
>>
>> AnthonyR.
>>
>
> How about the simple way? Find out the average color of the scene,
> assume that that average corresponds more or less to white - or
> grey, which is a dirty white :-) - and choose a balance that makes
> that average color look white.
>
> This amounts to adjusting the gain of two of the colors so that
> their average intensity equals that of the other color. Let us say,
> adjust the levels of red and blue to match that of green.
>
Your method is too slow. Find the most white and the most dark and make
them so and interpolate all other intensities between those ends.
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