Ad
Ad
Ad
Pages: « 1 [2]   Bottom of Page
Print
Author Topic: A Question of White Balance  (Read 6834 times)
BartvanderWolf
Sr. Member
****
Offline Offline

Posts: 3907


« Reply #20 on: February 08, 2010, 07:43:32 AM »
ReplyReply

Quote from: Ed Blagden
This all makes me wonder how on earth we managed back in the days of slide film - somehow a colour temperature of 5200K (at least for outdoor) seemed to work just fine in almost every outdoor situation.  Don't get me wrong: I love digital, am not a Luddite and would never go back.  However I sometimes think that one unfortunate side effect of digital is that we all spend far too much time worrying about things which don't really matter very much.

2 reasons how we managed.
1. By using filters (color correction and color compensating).
2. During the output process (either projection or print) color was adjusted.

Since we didn't have other options we just had to accept the result.

Quote
And speaking of WB related things which don't matter very much in the grand scheme of things: I live at high-ish altitude on the equator and have noticed that AWB tends to produce a reading 500K to 1000K below where it would be at sea level in more northern latitudes.  For example a sunlit outdoor scene in Nairobi (~6000 feet, ~1 degree south of the Equator) might give me a AWB setting of about 4500K and a similar scene in southern England would give me around 5200K.  Anyone have any idea of the physics behind this?  Not that it matters very much.

It's possibly caused by secondary absorptions of the filter dyes in the sensor array's CFA. As a result Ultra-Violet exposure could boost the response of the Red sensitive sensels, or IR light could boost Blue response, it depends on the CFA characteristics. Also the strength of the IR filter in front of your camera's AA-filter can play a role. Whether that's the real cause requires further tests and may give different results on different camera models. You could try shooting with, and without, a UV filter and see how your camera responds. When you shoot a spectrally uniform reflecting target, you can easily repeat the test at different latitudes/heights.

Cheers,
Bart
Logged
EduPerez
Sr. Member
****
Offline Offline

Posts: 696


WWW
« Reply #21 on: February 08, 2010, 08:42:30 AM »
ReplyReply

Quote from: BartvanderWolf
I understand, but that's not how the human visual system works. We mentally correct (WB) the image, and our camera doesn't. That's why shadows look so blue in an image that's color balanced for daylight, and we didn't notice it when we looked at those same shadows as we shot the image. When we look at a piece of white paper, we will always see it as white, regardless of the dominant lightsource (Tungsten of daylight), the camera will show it as a color cast.

It's a similar 'problem' as with the eye's adaptation for light and dark areas in a scene. The camera doesn't alter the exposure dynamically thoughout the scene, our eyes do.

Cheers,
Bart

Yes, I am aware of the human issue... but what I am trying to do is avoid the 'correction'; for the sake of simplicity, let's assume I am trying to use the camera as a colorimeter: if the camera sees something as red, I want it to tell me "dude, this looks like red", instead of "dude, this looks like red, but I know the light was red, so it must be white".
Logged

Peter_DL
Sr. Member
****
Offline Offline

Posts: 423


« Reply #22 on: February 08, 2010, 02:05:47 PM »
ReplyReply

Quote from: John Camp
If you know where "neutral" is with a grey or white card, or a color checker, or a whibal, and have some kind of grip on normal color temps during the day (or temps that you want) -- the temps of full sun at noon, open shade, cloudy, early morning/larger afternoon, etc., you should then be able to quickly dial in the actual color, instead of screwing around trying to get it by playing with sliders & etc.
That’s basically my take as well.

With a new camera I shoot the color checker chart at full noon sun in order to click-whitebalance the second gray in the Raw converter (ACR).  Temp and Tint are saved as Own-Daylight-Preset. Some warmer and colder variants thereof are then created mainly by means of the Temperature slider but also by co-adjusting Tint in way that the Green channel stays well placed in between Red and Blue.

Nothing against "adjust to taste", but I think the subject matter it is also a question of calibration – at least to define the starting point. Whereas the Daylight preset "as shipped" does not even come close. Further, remember that daylight film with its fix response often enough just did it right (not always of course). So it's possible.

Reminds me of one of my very first posts elsewhere.
Seems there always have been different opinions on this subject.

Peter

--
Logged
vgogolak
Sr. Member
****
Offline Offline

Posts: 337


WWW
« Reply #23 on: February 08, 2010, 06:18:03 PM »
ReplyReply

Quote from: Eric Myrvaagnes
Indeed. Some folks seem to feel there are two "rules" of good landscape photography:

1. Only photograph early or late in the day because the light is so gorgeous then, and

2. Always set white balance with a WhiBal (or comparable) so you can destroy that beautiful light and make the scene look like mid-day.   

I, too, stopped using my WhiBal after a few days once I realized I was no longer getting the sunset warmth that daylight film gave.

I agree: Season to taste!

Eric

Absolutely-that's the simple result of WB by card; everything is 'normalized' to mid-day, 5500K (or whatever!)

Here's a shot that has always intrigued me since I remmeber it well; a shot with DMR (who's color I really like, along with the Digilux 2 and the M9/M8 Leica really seems to try hard for an aesthetic look, maybe even filmic, and yes, maybe a BIT old fashioned, but to my eye quite good.)

Here's what the DMR did first; it was 5pm, sun in back, low on horizon-- the outdoor equivalent of Tungsten!  LOL.

Then WB using the strip of white on the plane (pretty similar with the aluminium, but watch it, the grey isn't really grey)

Yes, it looks good, maybe better to some, but definitely loses the "late in day" look

Victor

PS GREAT comments here; we are getting away from the tech, back to the "art" approach to photography. Michael, Kudos for seeing the importance of this!
« Last Edit: February 08, 2010, 06:23:07 PM by vgogolak » Logged
BartvanderWolf
Sr. Member
****
Offline Offline

Posts: 3907


« Reply #24 on: February 08, 2010, 06:47:17 PM »
ReplyReply

Quote from: vgogolak
Absolutely-that's the simple result of WB by card; everything is 'normalized' to mid-day, 5500K (or whatever!)


That's just one use of a WB card, when the colors must be right. More common is to use the WB card as a basis to depart from along the color temperature path, without ugly green or magenta tint.

Cheers,
Bart
Logged
vgogolak
Sr. Member
****
Offline Offline

Posts: 337


WWW
« Reply #25 on: February 09, 2010, 10:58:35 AM »
ReplyReply

Quote from: BartvanderWolf
That's just one use of a WB card, when the colors must be right. More common is to use the WB card as a basis to depart from along the color temperature path, without ugly green or magenta tint.

Cheers,
Bart

Hmmm... You raise an interesting point. When a WB card is in the image, we can do a lot with it..take out a color cast, or a 'mixed light' like fluorescent and tungsten..

However, my understanding was that the 'eyedropper' in most applications assumes that the pixel selected (or is it a group?) is either x,x,x for RGB or follows a Plank distribution for 5500K. These are not the same, since sunlight is roughly a 'black body' at 5500K and R and B are lower than G in emissivity. However, we mostly get white/grey as x,x,x yes?

Why not an 'ambient light' eyedropper? that is, select the WB card and tell it the car is illuminated by tungsten (2800K?) and will adjust accordingly.(say white as 240, 220,200)

That way green/magenta casts will be corrected but the image wont turn a warm lamp lighted image into a bluish 'daylight' look.

The bottom line is that I find in C1 esp I scroll through the profiles for the appropriate 'look' for the image. It is almost always 'warmer' than a WB gives.

Bart, since you raised the issue, do you have an idea how the WB could be used in say PS or C1 to remove color cast but preserve th 'as shot' look?

best regards
Victor
Logged
BartvanderWolf
Sr. Member
****
Offline Offline

Posts: 3907


« Reply #26 on: February 09, 2010, 02:24:27 PM »
ReplyReply

Quote from: vgogolak
Hmmm... You raise an interesting point. When a WB card is in the image, we can do a lot with it..take out a color cast, or a 'mixed light' like fluorescent and tungsten..

However, my understanding was that the 'eyedropper' in most applications assumes that the pixel selected (or is it a group?) is either x,x,x for RGB or follows a Plank distribution for 5500K. These are not the same, since sunlight is roughly a 'black body' at 5500K and R and B are lower than G in emissivity. However, we mostly get white/grey as x,x,x yes?

Hi Victor,

The white balancing by eyedropper results in R=G=B. If the subject clicked on was spectrally neutral, i.e. it reflects all wavelengths that may fall on it in the exact same proportions, then all other neutral reflecting objects receiving the same light will also be neutral, and colored objects will retain their actual reflection color (assuming the sensor arrays has a neutral response to all wavelengths involved).

Quote
Why not an 'ambient light' eyedropper? that is, select the WB card and tell it the car is illuminated by tungsten (2800K?) and will adjust accordingly.(say white as 240, 220,200)

That way green/magenta casts will be corrected but the image wont turn a warm lamp lighted image into a bluish 'daylight' look.

The bottom line is that I find in C1 esp I scroll through the profiles for the appropriate 'look' for the image. It is almost always 'warmer' than a WB gives.

It's easier to make a neutral WB and change it with the temperature slider to taste. Ambient light is not only caused by the illuminant (which may have a discontinuous spectral output), but it also contains reflected/transmitted light from other objects in the area.

As an example consider an object of a given color, under a blue sky with direct sunlight falling on the object from one side, on a grass lawn. The ambient light will be a mix from direct sunlight filtered by the atmosphere together with some blue sky on one side together with the reflection of the grass (the percentage of the reflection reduces with the distance of the object above the ground). The part that's on the shadow side will lack the direct filtered sunlight but have an increased percentage of blue from the sky together with the grass.

Quote
Bart, since you raised the issue, do you have an idea how the WB could be used in say PS or C1 to remove color cast but preserve th 'as shot' look?

I haven't given it any thought before because it's impractical to what I want to achieve (an accurate baseline color balance or accurate colors), but perhaps you can do something in C1 with the Skin Tone control, e.g. by sampling something lit by different (filtered) lightsources, or a chart with colored (simulated blackbody) patches. As the C1 'manual' says:"The Skin Tone tool is created to adjust a selected color to an already defined color. by adjusting the white balance of the capture.". So you could define an off-white color as neutral and presumably the other colors will folow that shift. It won't solve the issue of mixed ambient light though, it will just create a WB shift.

Cheers,
Bart
Logged
douglasf13
Sr. Member
****
Offline Offline

Posts: 547


« Reply #27 on: February 09, 2010, 04:23:33 PM »
ReplyReply

Quote from: Ed Blagden
This all makes me wonder how on earth we managed back in the days of slide film - somehow a colour temperature of 5200K (at least for outdoor) seemed to work just fine in almost every outdoor situation.  Don't get me wrong: I love digital, am not a Luddite and would never go back.  However I sometimes think that one unfortunate side effect of digital is that we all spend far too much time worrying about things which don't really matter very much.

And speaking of WB related things which don't matter very much in the grand scheme of things: I live at high-ish altitude on the equator and have noticed that AWB tends to produce a reading 500K to 1000K below where it would be at sea level in more northern latitudes.  For example a sunlit outdoor scene in Nairobi (~6000 feet, ~1 degree south of the Equator) might give me a AWB setting of about 4500K and a similar scene in southern England would give me around 5200K.  Anyone have any idea of the physics behind this?  Not that it matters very much.

Ed

  I agree.  Some of the shooters over on the getdpi forums recommended something to me that has freed me up quite a bit.....I only shoot in with either daylight WB or tungsten WB!    This method reminds me much more of shooting film, and gives me a sense as to how the camera handles certain scenes.  Of course, I can always adjust WB in raw if need be, but I try to leave it alone for the most part.  My whiBAL has been relegated to studio shoots only, just in case.
« Last Edit: February 09, 2010, 04:24:50 PM by douglasf13 » Logged
pegelli
Sr. Member
****
Offline Offline

Posts: 609



WWW
« Reply #28 on: February 10, 2010, 01:45:53 AM »
ReplyReply

I'm very much agreeing with Michael, and I think we shouldn't turn WB into a science when the objective is to make a pleasing picture.

However I still use my WhiBal regularly to have a starting point which is close to 'neutral' and then adjust to make the picture look as I want it. I find that if I do not have a WhiBal reference that my pictures over the time of a PP session will develop some kind of color cast, not so much on the Temperature scale, but more on the green-magenta scale.
Logged

pieter, aka pegelli
BartvanderWolf
Sr. Member
****
Offline Offline

Posts: 3907


« Reply #29 on: February 10, 2010, 04:14:29 AM »
ReplyReply

Quote from: pegelli
I'm very much agreeing with Michael, and I think we shouldn't turn WB into a science when the objective is to make a pleasing picture.

However I still use my WhiBal regularly to have a starting point which is close to 'neutral' and then adjust to make the picture look as I want it. I find that if I do not have a WhiBal reference that my pictures over the time of a PP session will develop some kind of color cast, not so much on the Temperature scale, but more on the green-magenta scale.

That's right, our eyes adapt and it becomes increasingly difficult to avoid a bias, especially when our viewing conditions during post-processing are suboptimal (think brightly colored shirts or mixed room lighting with a different color temperature that our display calibration). It only makes sense to occasionaly include a WB reference during a series of shots to keep us on track. I find it only too easy to gradually create more magenta images than I intended. Color temperature is used to set the atmosphere in the image if the colors don't need absolute accuracy.

Cheers,
Bart
Logged
OrangeNature
Newbie
*
Offline Offline

Posts: 2



WWW
« Reply #30 on: February 12, 2010, 02:56:40 AM »
ReplyReply

I use WhiBal as a starting point, then I season color as I like. But it is a good article it can be tempting to always have exact "correct" whitebalance.
Logged

Photography enthusiast and traveler

Orange Nature
Philmar
Sr. Member
****
Offline Offline

Posts: 355


WWW
« Reply #31 on: February 12, 2010, 11:59:20 AM »
ReplyReply

Quote from: Jeremy Payne
I'm not sure why you need a grey card at all ...

Since you seem to recognize that the 'right' white balance is the one that looks the most pleasing to you relative to your intended output, why not leave the grey card at home?

I agree. the only time the card is useful is in specific situations where having a good starting or reference point would be helpful. For example when I was shooting in Petra and most of my shots were of red/orange rock formations and blue sky. Very little white/black/grey subject matter. Problem is compounded when some of the shots are taken in complete shade, complete bright sunlight (at varying times of the day), cloud and then shots with both sunny and shady elements. It is difficult to find a good starting point when selecting an appropriate w/b. I found that after processing individual shots that the rocks seemed of varying orange/red or green/magenta. Using a grey card would have provided me with a useful starting point in that situation.
The card would have definitely helped when I shot in Wadi Rum - a desert where the rocks and sands are of varying shades of orange, red and yellow.
Logged

An office drone pension administrator by day and a photo-enthusiast by night, week-end and on vacation who carries his camera when traveling the world:
Please have a chew on my photos:
http://www.fluidr.com/photos/phil_marion/sets
Philmar
Sr. Member
****
Offline Offline

Posts: 355


WWW
« Reply #32 on: February 12, 2010, 12:06:44 PM »
ReplyReply

Quote from: BartvanderWolf
These types of shooting scenarios can also happen in urban surroundings with colored buildings, or under mixed lighting (especially when discontinuous spectral lightsources are added to the mix).

Cheers,
Bart

As well as in the situation I described above.
Logged

An office drone pension administrator by day and a photo-enthusiast by night, week-end and on vacation who carries his camera when traveling the world:
Please have a chew on my photos:
http://www.fluidr.com/photos/phil_marion/sets
Chris_T
Sr. Member
****
Offline Offline

Posts: 541


« Reply #33 on: February 15, 2010, 07:43:04 AM »
ReplyReply

Quote from: ChristophC
I stopped caring about "correct" white balance too much after I understood,
that always shooting a metamerism free grey card and/or a colorchecker
simply helps me to completely destroy the light atmosphere.

Congratulations! You are now an official recovered WB Abuser.

Some references to support your decision:

http://luminous-landscape.com/forum/index....st&p=341597

http://photo.net/digital-darkroom-forum/00VNcE

Quote
What I do now is to look how the color would look if I use the grey card for white balance and how the whitebalance
would be changed if I used the daylight setting in the RAW converter. So I get a sort of measurement of the color
temperature at shooting time and can now moderately adjust the whitebalance between the extreme color of the non
whitebalancing daylight setting and the neutralizing greycard mode and adjust it somewhere in between to my liking.

As others have suggested, you don't need the gray card. Instead, in Raw conversion, rely upon your memory and/or taste.

"The negative is comparable to the composer's score and the print to its performance. Each performance differs in subtle ways." - AA

Still true by replacing "negative" with "sensor capture", and add "or jpeg" after "print".
Logged
Eric Myrvaagnes
Sr. Member
****
Offline Offline

Posts: 8291



WWW
« Reply #34 on: February 15, 2010, 09:50:44 AM »
ReplyReply

Quote from: Chris_T
Congratulations! You are now an official recovered WB Abuser.

Some references to support your decision:

http://luminous-landscape.com/forum/index....st&p=341597

http://photo.net/digital-darkroom-forum/00VNcE



As others have suggested, you don't need the gray card. Instead, in Raw conversion, rely upon your memory and/or taste.

"The negative is comparable to the composer's score and the print to its performance. Each performance differs in subtle ways." - AA

Still true by replacing "negative" with "sensor capture", and add "or jpeg" after "print".

Right on!


I suspect that much of the longing for film we keep hearing about results from the over-use of so-called "correct" white balance.

I'm sure if AA were around now, he would have lots to say about how to get the right white balance for the mood you want to create (or recreate).

Eric

Logged

-Eric Myrvaagnes

http://myrvaagnes.com  Visit my website. New images each season.
Christoph C. Feldhaim
Sr. Member
****
Offline Offline

Posts: 2509


There is no rule! No - wait ...


« Reply #35 on: February 15, 2010, 11:50:04 AM »
ReplyReply

Quote from: Chris_T
Congratulations! You are now an official recovered WB Abuser.

Logged

Chris_T
Sr. Member
****
Offline Offline

Posts: 541


« Reply #36 on: February 16, 2010, 07:15:18 AM »
ReplyReply

Quote from: Eric Myrvaagnes
I suspect that much of the longing for film we keep hearing about results from the over-use of so-called "correct" white balance.

I'm sure if AA were around now, he would have lots to say about how to get the right white balance for the mood you want to create (or recreate).

The use and mis-use of WB is a good example of what digital imaging brings. Like many digital tools and features, it is wonderful when used appropriately and horrible when used wrong. I attribute why many users mis-use these features and tools to the following:

- the vendors tell them they must have them
- after money spent, why not use them when they are there
- books and tutorials tell them they will solve their problems, without any context
- they hope that these will finally make them better photographers

Some photographers, like this one, got it right and stopped climbing the digital hamster wheel and returned to being photographers.

http://www.huntingtonwitherill.com/pdf/Hamster_Wheel.pdf
Logged
Eric Myrvaagnes
Sr. Member
****
Offline Offline

Posts: 8291



WWW
« Reply #37 on: February 16, 2010, 08:56:45 AM »
ReplyReply

Quote from: Chris_T
The use and mis-use of WB is a good example of what digital imaging brings. Like many digital tools and features, it is wonderful when used appropriately and horrible when used wrong. I attribute why many users mis-use these features and tools to the following:

- the vendors tell them they must have them
- after money spent, why not use them when they are there
- books and tutorials tell them they will solve their problems, without any context
- they hope that these will finally make them better photographers

Some photographers, like this one, got it right and stopped climbing the digital hamster wheel and returned to being photographers.

http://www.huntingtonwitherill.com/pdf/Hamster_Wheel.pdf
Indeed.

Witherill does gorgeous work.


Eric

Logged

-Eric Myrvaagnes

http://myrvaagnes.com  Visit my website. New images each season.
Pages: « 1 [2]   Top of Page
Print
Jump to:  

Ad
Ad
Ad