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-   -   Correct White Balance Doesn't Mean Correct Color?? (http://www.velocityreviews.com/forums/t419311-correct-white-balance-doesnt-mean-correct-color.html)

jim evans 10-21-2005 03:08 AM

Correct White Balance Doesn't Mean Correct Color??
 
I read in google groups where someone posted this statement in this
group:

". . white balance . . . is the first step but not quite the same
thing [as correct color balance]. I.e., you can have poor color even
if the white balance is set right. "

Is this true? If so, why?

jim

Steve Cutchen 10-21-2005 03:34 AM

Re: Correct White Balance Doesn't Mean Correct Color??
 
In article <hjmgl1luso5qoh3jvvk4mdad74jaivj2sg@4ax.com>, jim evans
<jimsTAKEOUTnews2@houston.rr.com> wrote:

> I read in google groups where someone posted this statement in this
> group:
>
> ". . white balance . . . is the first step but not quite the same
> thing [as correct color balance]. I.e., you can have poor color even
> if the white balance is set right. "
>
> Is this true? If so, why?
>
> jim


Just a simplistic guess... but if white balance was right and exposure
was wrong, color would be wrong.

bmoag 10-21-2005 03:44 AM

Re: Correct White Balance Doesn't Mean Correct Color??
 
Color is what you choose it to be and correct white balance may destroy the
effect you are seeking:?
Duh?



GTO 10-21-2005 03:44 AM

Re: Correct White Balance Doesn't Mean Correct Color??
 
Yes.

Why? Please read
http://www.earthboundlight.com/photo...gray-card.html. His
well written page is easier to understand than my 5 minutes summary of it
;-)

Gregor


"jim evans" <jimsTAKEOUTnews2@houston.rr.com> wrote in message
news:hjmgl1luso5qoh3jvvk4mdad74jaivj2sg@4ax.com...
>I read in google groups where someone posted this statement in this
> group:
>
> ". . white balance . . . is the first step but not quite the same
> thing [as correct color balance]. I.e., you can have poor color even
> if the white balance is set right. "
>
> Is this true? If so, why?
>
> jim




MarkČ 10-21-2005 04:28 AM

Re: Correct White Balance Doesn't Mean Correct Color??
 
jim evans wrote:
> I read in google groups where someone posted this statement in this
> group:
>
> ". . white balance . . . is the first step but not quite the same
> thing [as correct color balance]. I.e., you can have poor color even
> if the white balance is set right. "
>
> Is this true? If so, why?


The quotee was likely referring to *preset* WB settings, such as
flourescent, tungsten, flash, etc.

-Most environments have a *mixture* of light sources...and these sources
create WB situations that do not fit neatly into the preset WB settings on
the camera. A camera's WB settings assume that the SOLE source of light is
that which it indicates (ALL flash, for example). When you shoot in these
mixed lighting environments, it's almost NEVER going to be the perfect WB.
This means that if you're picky, you'll still want to make at least minor
adjustments.

In addition...If you're shooting a concert, and you want to preserve the
blue light or red light of the stage, etc., you won't want the camera to try
and compensate for the red light, etc.

This is why no matter how "smart" camera tech becomes, it is STILL always up
the photog to take control...if you want final say over what you capture.

Custom white balance comes into play here, but even then, you can change the
nature of light simply by pointing in a somewhat different direction within
the same room, for example...where there may be a colored lampshade,
fourescent kitchen light, etc. etc.

Sitting here in my office, I have tungsten from a standard bulb...halogen
from a desk lamp...and light from both my computer and TV screen. Then
there's the hall lights casting rays into this room. As you can see...NO
camera WB is going to accurately handle this setting. When I'm doing
serious color work in Photoshop, I dim nearly all the lights in here, since
it will even throw your human vision off (!).
:)
-M2



Gary Hendricks 10-21-2005 04:49 AM

Re: Correct White Balance Doesn't Mean Correct Color??
 
Hi Jim,

Here's a good take on white balance from the Nikon pages:

http://nikondigital.org/articles/white_balance.htm


************************************************** ***************
Sincerely,
Gary Hendricks, Basic-Digital-Photography.com
The best digital photography tutorials and how-to guides:
http://www.basic-digital-photography.com
************************************************** ***************


jim evans 10-21-2005 06:16 AM

Re: Correct White Balance Doesn't Mean Correct Color??
 
Thanks for the replies. But, either I didn't understand them or they
don't address my question. I understand what white balancing is and
why it's done.

Perhaps I need to better define things.

By "white balance" I mean including a gray card in the image and
adjusting the color such that the card is gray -- R=G=B.

By "correct color" I mean the color of any area or object in the image
matches the color of the actual area or object photographed.

Someone said "Color is what you choose it to be." I don't agree. A
given red fire engine is a specific color of red. If you render it
correctly the image will be the same red as that fire engine.

Someone else said: "A camera's WB settings assume that the SOLE
source of light is that which it indicates (ALL flash, for example).
When you shoot in these mixed lighting environments, it's almost NEVER
going to be the perfect WB. This means that if you're picky, you'll
still want to make at least minor adjustments."

This statement assumes the white balance is not correct. My question
assumes the white balance is set correctly and asks if this statement
is correct and if so why.

>". . white balance . . . is the first step but not quite the same
> thing [as correct color balance]. I.e., you can have poor color even
> if the white balance is set right. "


You will note the statement assumes the white balance is correct and
says even then you can have poor color.

So rephrasing my question -- how can colors be wrong when the white
balance is correct?



jim

MarkČ 10-21-2005 06:52 AM

Re: Correct White Balance Doesn't Mean Correct Color??
 
jim evans wrote:
> Thanks for the replies. But, either I didn't understand them or they
> don't address my question. I understand what white balancing is and
> why it's done.
>
> Perhaps I need to better define things.
>
> By "white balance" I mean including a gray card in the image and
> adjusting the color such that the card is gray -- R=G=B.
>
> By "correct color" I mean the color of any area or object in the image
> matches the color of the actual area or object photographed.
>
> Someone said "Color is what you choose it to be." I don't agree. A
> given red fire engine is a specific color of red. If you render it
> correctly the image will be the same red as that fire engine.


That fire engine appears as one version of "red" at sunset, and another
version of "red" during mid-day.
The "red" you wish to depict in your image IS, in fact, up to you to the
extent you control your camera's rendition.

>
> Someone else said: "A camera's WB settings assume that the SOLE
> source of light is that which it indicates (ALL flash, for example).
> When you shoot in these mixed lighting environments, it's almost NEVER
> going to be the perfect WB. This means that if you're picky, you'll
> still want to make at least minor adjustments."
>
> This statement assumes the white balance is not correct.


No it doesn't. It assumes that the present WB settings on any camera CANNOT
be preset to account for the limitless variations of lighting soources that
exist all over the place.

>My question
> assumes the white balance is set correctly and asks if this statement
> is correct and if so why.


That's a very large assumption.
What do you mean by "set correctly"?
Do you mean a custom white balance?
Or do you simply mean one of the preset WB choices offered by your camera
(sunny, cloudy, shade, etc.)?
If it's the second one, then you will find that SOMETIMES it works--when in
a very typical sunny scene, or 100% flourescent-lighted room...but its
common to have a mixture of light qualities/sources, each with a different
color cast that mixes with others (sunlight through a big window, but
flourescent lighting inside). This means that neither sunny WB nor
flourescent camera WB settings will be accurate. This is where creating a
custom WB is beneficial...or...taking the time to tweak the color balance in
photoshop after the fact.

>
>> ". . white balance . . . is the first step but not quite the same
>> thing [as correct color balance]. I.e., you can have poor color even
>> if the white balance is set right. "

>
> You will note the statement assumes the white balance is correct and
> says even then you can have poor color.


I think there is still some question as to what you are referring to as
"correct WB is set."

> So rephrasing my question -- how can colors be wrong when the white
> balance is correct?


They shouldn't be, unless you've over or under-exposed the image.
But still, I suspect you may not be as "correct" as you think.
Explain further so we can answer your question:
-How are you determining that your WB settings are "correct?"
What basis are you using to establish your certainty of this?
I'm not challenging you... It's just that without knowing what you mean, it
leaves a huge question mark which prevents a helpful, accurate answer.



Steve Wolfe 10-21-2005 06:55 AM

Re: Correct White Balance Doesn't Mean Correct Color??
 
>I read in google groups where someone posted this statement in this
> group:
>
> ". . white balance . . . is the first step but not quite the same
> thing [as correct color balance]. I.e., you can have poor color even
> if the white balance is set right. "
>
> Is this true? If so, why?


Partly so. It's not because white balance shouldn't set all of the colors
correctly in theory, it's because of real-world deviations from the ideal.
Different sensors (or monitors, printers, or any other color-related device)
will have some non-linearity in how receptive they are to colors at
different intensities. Put another way, they will react somewhat
differently to a red object that's brightly lit than if it is not brightly
lit. To make it even better, each of the colors will behave differently as
well - it won't react the same way to a bright blue ball as to a bright red
ball.

Here's an example - take a monitor calibration device, and set the white
point correctly on a monitor - either LCD or CRT. Does that make the colors
look right? Nope, not at all - the device will need to go through and
analyze the color response to different colors and different intensities to
create a custom profile.

As for your camera, the firmware is sufficiently aware of the properties
of the average sensor in that model to get things pretty close. If it's not
close enough, there is a part in "Real World Camera Raw" that goes over how
to set the various parameters in ACR to match your individual camera. I
suspect that "Real World Color Management" would go to even greater lengths.
You can also get products from the various color-management companies that
will develop a custom profile to match your camera's specifics.

All of that being said, you need to take it with a grain of salt. Your
camera will do a reasonable job of getting close enough if the white balance
is correct. Besides that, in the majority of photography, you rarely want
100% accurate color anyway. Most of the time you're trying to manipulate
things to make them look flattering, not accurate - in fact, it's common to
completely discard color, and shoot black and white when color won't be
flattering. Look at pictures of newborns, the great majority of them are
B&W, as they usually have complexions that aren't terribly flattering in
color. Even when you're shooting a color picture, you generally try to
emphasize certain hues or colors. In the end, most photographs are about
what you WANT them to be.

steve



Chris Brown 10-21-2005 09:30 AM

Re: Correct White Balance Doesn't Mean Correct Color??
 
In article <9t1hl19b60vpumoj7muito89615k9big1l@4ax.com>,
jim evans <jimsTAKEOUTnews2@houston.rr.com> wrote:
>Thanks for the replies. But, either I didn't understand them or they
>don't address my question. I understand what white balancing is and
>why it's done.
>
>Perhaps I need to better define things.
>
>By "white balance" I mean including a gray card in the image and
>adjusting the color such that the card is gray -- R=G=B.
>
>By "correct color" I mean the color of any area or object in the image
>matches the color of the actual area or object photographed.


Therin lies the rub. Adjusting the white balance so that the grey card is
grey can make the colours wrong in some images (think sunsets), or may not
even be possible in others (think sodium light).

In a nutshell, if white balance is set from a grey card then the colours
will be wrong if the grey card didn't look grey to the photographer when she
took the picture.


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