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Home >> Photography >> Digital White
Balance Tools
Resolution is important because it defines the relative size of the enlargements possible from a given camera. Low noise performance is important because it allows us to take photos in low ambient light settings – given the types of photography I have been doing recently, I would take a relatively lower resolution camera with superb high ISO capabilities, as in ISO 3200 being as noise-free and detailed as my Nikon D100’s ISO 400 setting. White balance affects the color balance of a digital file, as measured in degrees of Kelvin. For reference, a sunny noontime kind of light is 5500K and is what most films are calibrated for to provide accurate color balance. Use the daylight balanced films outside of the couple of hours straddling both sides of noontime and you will have affected the color balance if you were to use them during the prime time of best light in the early morning or late afternoon. The use of filters helps to mitigate the effects of the light and many photographers choose to use a Skylight or 81A warming filter not as protection for the lenses, but to affect a slightly warmer color balance and/or counteract the blue cast in skylight. The flower shot below shows the effects of a warm filter (right shot) in overcast light with the red arrow pointing out the obvious change in color for the bricks in the background.
For digital photographers, we literally have a pocketful of color correction filters built into the camera thanks to the white balance control. No serious camera is without this important feature and most digicams also offer user controllable settings for the white balance. Most consumer digicam users are likely using the Auto White Balance (AWB) setting on their cameras, but a fair number of serious D-SLR users also use AWB. D-SLR users shooting in RAW mode (an image file that has no in-camera processing, as opposed to JPEGs and TIFFs that do) have the luxury of being able to change various settings during RAW conversion to a more usable file format for Photoshop or other editing. White balance is one of those user-selectable settings that can be modified at will to achieve either a more accurate color balance or one that suits the photographer’s aesthetic needs. Other photographers prefer to shoot JPEGs to achieve greater performance from their cameras for speed of shooting and buffer size that is not available when shooting in RAW mode. For these photographers, the ability to edit the color balance in post-production is not necessarily impossible, but you do so at the risk of tossing away image data that can affect your image deleteriously. For JPEG shooters, you want to ensure a bang on exposure and color balance at the time of exposure and not in an image editing application. Part of it has to do with JPEGs being 8-bit files whereas most RAW files are 12-bit and then opened up as 16-bit files in an editor like Photoshop. Those extra bits provide greater tonality and ability to edit without losing too much data from the original image file compared to 8-bit JPEGs. Even RAW shooters should strive for as accurate an exposure and color balance as possible to save on the amount of editing time required, especially if you are working on hundreds of files. One offs or a few dozen here and there allow the luxury of time to edit to your heart’s content, but it takes a stout heart to sit in front of a computer for hours on end editing a job of hundreds or thousands of files. Some basics about how to optimize exposures with a digital camera has already been posted, so we now turn our attention to obtaining accurate white balance for obtaining neutral colors, using various tools, cheap and expensive. White balance is a result of the quality of light we photograph in. Shoot in warm, tungsten lit environments and you generally obtain an image with an orange cast as the color balance shifts to red. Shoot in outdoor light or with flash and you end up with images that will shift to the blue range of the color spectrum. Florescent lights offer their own challenges and old time film users used magenta filters to counteract the green tones found in such lights, which makes imminent sense as magenta is the complimentary opposite of green, just as cyan is for red and yellow is for blue. Most cameras offer selectable WB settings in addition to AWB. These are usually fairly straightforward such as Tungsten, Sunny, Cloudy, Flash, Shade, and Florescent. These WB settings are usually one specific color temperature setting, but most cameras offer some upward or downward adjustment of the color temperature. For example, my Nikon D100 has the noted WB settings mentioned above, but allows for 1/3 increment settings of a specific WB for up to plus or minus 3 settings (Moose Peterson is noted for his favored choice of Cloudy –3 with his Nikon D-SLRs). I'd prefer the Canon method of offering actual degrees in Kelvin rather than plus or minus settings that don't tell you exactly what the color temperature is.
Selectable WB does not always work as well as desired and AWB can be hit and miss, especially for light sources that aren’t listed in the Custom settings, or you’re faced with mix lighting conditions, e.g., sodium vapor lamps, stage lighting, etc. You could use the closest equivalent in the user selectable settings or just use AWB and then try to neutralize the color cast in post production (which is easy if you’re shooting RAW mode, but less easy for JPEGs), or else use a custom WB setting for the camera. A custom, or preset, WB setting requires a grey or white card to allow the camera to lock in a particular color temperature based on what it sees from the reference card. You set the camera to its custom WB mode and with whichever lens you’re using, fill the frame with the grey or white card and take an exposure. The camera takes a second to process the information and will indicate whether the custom WB is good or not. Obviously you want to ensure that you hold the grey card in such a way so that the ambient light falls on it in order to take a custom WB reading.
Other methods of correcting the color balance for a file is to place a grey card in a test shot for later reference in editing. Open up the test shot first and then using Levels or similar control in the image editing software, use the middle grey eyedropper to sample the grey card and obtain a neutral colorcast. Save the Levels profile into a folder and then utilize the same profile for all the other files shot in the same lighting condition as the test. This is something that can be done for RAW and JPEG files, but with the caveat that you may degrade a JPEG file with postproduction, so best to save as a 16-bit TIFF before doing any editing. Even better than a grey card reference is a grey, AND a white, AND a black reference, so you get all three key points to reference later on in Photoshop. Michael Tapes makes such reference cards as the WhiBal product. The WhiBal cards are attached together by a corner stud that allows the cards to be fanned out and placed in your subject scene for later WB correction.
While WhiBal would seem to indicate that the cards are as simple as just holding them out with your left arm while you hold the camera and take the reference photo with the right arm, it isn’t quite that simple for best results. For taking photos of a room for example, it would be better to place the cards right in the key area where the light is dominant or consistent rather than arm's length away from the camera. Do the former and your results should be quite accurate, but do the latter and while you can still achieve some decent results, you run the risk of blowing out the highlights when you use the highlight dropper from the Levels window to reference the white card. The WhiBal cards seemed like the right WB tools for photographers on the go and moving from scene to scene with varying lighting conditions. Rob Galbraith noted that the WhiBal cards work best for RAW capture rather than JPEG and as it happens, I shoot 99 percent RAW capture with my Nikon D100. The WhiBal products are claimed to absolutely neutral and even if scuffed or scratched, will not affect the ability to obtain an accurate WB. My package of two sets of cards cost me about CAN $100 after exchange, S&H, and taxes were applied. Another way to obtain neutral color balance is with an accessory called the ExpoDisc.
I wasn’t intrigued by the price asked for the ExpoDisc, but when a reader of this web site praised it mightily to me in an email, I thought, what the hell, it’s only money, even if it cost me over CAN $200 (US $160 for the 77mm size version at time of purchase a couple of years back). Canadian purchasers can buy from Vistek in Toronto and avoid customs hassles. Sizes range from 58mm to 95mm in round filter sizes, as well as 4x4 inch for filter holders. Prices range from modestly extortionate to peversely astronomical even for the world of photography given that you're buying some fancy pieces of plastic, but then some would say the same of the highly regarded Singh-Ray filters that are in the camera bags of a great many landscape-shooting pros. However, another mention in Rangefinder magazine set me off when the writer/photographer mentioned that all he needs at an event these days is a light meter, the ExpoDisc and he’s good to go for neutral WB right out of the camera. If it’s that good then $200 sounds like a cheap investment for easy editing. We’ll see how it does, but first some basics about it, as gleaned from their 12-page information document available at the company’s web site.
There are a few other points in the company’s document, which is pretty detailed for how the ExpoDisc works and various tips to obtain the best from it. There are also tips from professional photographers about how to use the ExpoDisc with specific digital cameras in the field or in the studio. It took a while for me to get into utilizing the ExpoDisc for its intended purpose because I have been a lazy RAW file photographer for so long. Not being especially prolific, I could edit my personal image files quite manageably, but in recent times, as I have gotten more involved in photographing events at work, the idea of having to edit hundreds of files from a single event did not sit too well with me. The first such event a couple of years ago in which 300 plus image files were taken, I didn’t use the ExpoDisc because I didn’t have one back then. For that event I took some images of a grey card in the same light as I worked in and created a Levels profile to apply to other ambient light image files. It seemed to work well enough even if I had to tweak the files a bit; however, it still meant having to edit each file manually. Another problem was that I did not have a lot of compact flash cards or the Vosonic digital wallet and as such, I shot in JPEG mode to ensure that my meager supply of three 512 MB cards would be enough for the job. Again, having to correct the color in JPEG mode is doable but not advisable due to the potential loss of data, even if you convert to TIFF for editing. A few events later when I finally got down to working with the ExpoDisc, I used it for a pre-set white balance by placing it on my lens, pointed up towards the lights in the hotel ballroom and then using that white balance for many of the ambient light photos I took. About halfway through the event I went back to AWB because of flash use and kept it there for the rest of the ambient-light only shots. The results with the ExpoDisc from that first use didn’t exactly impress me. In fact, I was pretty disgusted with the grungy colors seen and only by tweaking the shots with the Curvemeister Photoshop plug-in was I able to get much better looking photos…the kind I had expected right off the bat and what the ExpoDisc marketing seemed to promise. However, one use alone does not make for enough experience, but it took me a while before I wanted to use the ExpoDisc again, despite its high cost. I needed to do a more controlled test and ensure that it wasn’t user error that got the bad looking photos. As it turned out, the ExpoDisc did return an accurate WB, it was just the ballroom’s lighting that made everything look pretty gross.
I found it in a one-liter sized can of GoodHost ice tea powder mix for CAN $8. My wife helpfully pointed out lower cost alternatives, but I insisted on the GoodHost mix without telling her why I really wanted it. “Well dear, I really don’t care about the ice tea mix, I really just want to spend $8 to, ahem, buy this white plastic lid.” If I had really said that, I'd probably be locked up at Riverview (the local institution for the mentally-challenged). Perusing the store shelves I found lots of other white plastic lids, but they all had writing on top of them, making them useless for WB needs.
Let’s see how each of these methods fare. I have to admit that based on the first use of the ExpoDisc, I wasn't expecting much of it and given how expensive it is to buy, I was really hoping I could just suggest that everyone go out and buy the GoodHost can lid for $8 and get one-liter of ice tea mix thrown in for "free," but such was not the result borne from my testing. The testing was done at night using my home office as the test subject. It's lit overhead by a centrally located chandelier of six small incandescent bulbs. I never have this light on when I'm editing, preferring to use a daylight temperature flourescent bulb in a desk lamp for low illumination. The desk light does double-duty as the light source for checking out my prints and comparing them to the images on the calibrated monitor. Images were shot in RAW mode and converted using Bibble 4.2.6 to JPEG and tagged with Adobe 1998 color space (images have not been converted to sRGB for the web). Below are all the different permutations I tried:
To my eyes, the ExpoDisc produced the most natural and accurate colors and since this is my room, I should know :-) The Click White option in RAW converters can get pretty good results provided that you actually have a white or grey area to click on for reference, such as from a grey or WhiBal cards. The other cheap methods, such as the GoodHost can lid and WB bars printed on Epson Matte paper, introduced color casts that are unacceptable. It just revealed that white is not necessarily neutral white and that ink dyes and papers are not suitable to create your own white balance tool on the cheap. Speaking strictly with tongue in cheek, I should note that because I could not use the old-style Pringles can lid for my testing, that I cannot speak for those that advocate this option and that maybe, there's something about Pringles lids that will provide as good a WB as the ExpoDisc ;-) I dislike the price of the ExpoDisc given it's material construction and there is no pride of ownership for this glorified filter, but there is no denying that it produces the goods in a more consistent fashion than other products, even those costing a fair bit of money (the WhiBal cards) and on this basis, the $200 cost for the 77mm size version is more acceptable. For those that edit hundreds or thousands of files on a regular basis, $200 is nothing compared to the hours saved from not having to edit and obtain a neutral white balance. I should note that these tools are for trying to achieve a technically accurate white balance setting, but technically accurate may have nothing to do with asethically pleasing based on the needs of your individual images.
Unless otherwise indicated, all dollar figures used are Canadian dollars, because, well...I am Canadian! (Canucks that drink Molsens will get that one :-) I took the sample photos in Aperture Priority mode with the D100 and did not adjust compensation. I wanted to use the camera in its regular mode for consistency, because to my eyes, not all the white balance tools are equal with regard to exposure, e.g. the ExpoDisc sample shot looked the best for both white balance and exposure. I called the company ExpoDisc, but this is incorrect, as the company is now called ExpoImaging. This is a reflection of the time period that I purchased the ExpoDisc. At the time of purchase, there was only one variant of the ExpoDisc. This version is now called the "Classic" with warmer versions available that add in an 81A level of warmth. There is also a Digital ExpoDisc that uses metal in its construction with a less thick outer ring, but honestly, other than these minor changes, I'm not certain what the actual differences are between the Classic and the Digital ExpoDiscs for affecting white balance. The only difference that I could find is that the Classic is only available in smaller sizes such as 52 and 55 mm and the Digital ExpoDisc is available from 58 to 82 mm. While I noted the availability of a 95 mm ExpoDisc, this was at the Canadian dealer Vistek's website, I did not see mention of such a monster, or the 4x4 inch versions being available from the ExpoImaging website. November 28, 2005 - Michael Tapes, the maker of WhiBal cards, sent along these comments:
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Correspondence & About this website Copyright © 1998-2008 Edwin Leong |
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Hang
around the various photography web sites catering to the digital
process for a time and eventually you will hear a term thrown
around called “white balance.” Some even consider this to be the
most important aspect of a digital camera’s performance, which
I think is a bit carried away. 
I
usually find that my own tastes run bluer than what some of the
custom WB settings provide and that certain settings such as Cloudy
or Shade are a bit too warm for my liking. But this does depend
on what I’m photographing, as each image will have it’s own WB
that works for it better than others, and of course, this is all
based on my own subjective tastes. The image at right was converted
from RAW with 
Once
the custom WB is set, you revert back to shooting mode and all
exposures taken will now reflect this color balance until you
adjust the WB setting again. The grey card method is relatively
cheap since grey cards sell for $20 or less. This is a favored
method for JPEG shooters because it helps to reduce post-production
editing significantly and allows for a fairly neutral color balance
(depending on the age and condition of the grey card).
There
is a pocket-sized version that’s about the size of a deck of bridge
cards and a larger set meant for use in a studio. I bought both
sizes because I can see times when I would want one or the other.
The 
Some
people have tried the ExpoDisc and then had a bright idea that
any white plastic lid would do the same job for mucho dinero less
in cost. The Pringles chip can lid has been bandied about as a
good sized lid, unfortunately, the current lids are now clear
translucent and not usable for comparison. In search of an alternative,
I shocked my wife by actually desiring to go grocery shopping
with her to our local Safeway. I, of course, had an ulterior motive
in search of an appropriate lid for this article.
Another
cheap WB alternative is to print out a black, grey, and white
reference bars with an inkjet printer using 0, 128, and 255 as
the numerical settings for the colors. A sheet of Epson Heavyweight
Matte paper is cheap like borsch at CAN $20 for 50 sheets and
the ink cost is pretty minimal since you’re just really printing
the grey and black bars.
August
16 - Update and clarification on some minor points brought
up by some that read the article.