This might be a dumb question, but I will ask any way, Does it make any difference if you use a flash for a custom white balance My images look a little cold with AWB,
Setting a custom WB will most likely give you very consistant, accurate colors. Just shoot a grey card for each lighting condition you deal with and that few seconds will save you time in post. IMHO AWB is the last setting that you should use. With auto WB the color temp will jump all over the place.
Question: In case you don't have a custom grey card with you, I heard there is a way to get the same HEX value (something like ffff99) if you roll over the mouse on the picture to identify something very close to the grey card. Is this correct? If so, what should be the exact HEX number (equivalent of grey) we should be looking for? May be this way, MS PHOTO can actually use the existing pictures to correct his WB. Thanks - Perla
PerlaD300 wrote:
Question: In case you don't have a custom grey card with you, I heard there is a way to get the same HEX value (something like ffff99) if you roll over the mouse on the picture to identify something very close to the grey card. Is this correct? If so, what should be the exact HEX number (equivalent of grey) we should be looking for?
You can't be looking for a hex number because the area you're thinking is close to neutral has an incorrect WB. I do this every once in a while. It works well if you find something near middle grey, but white tableclothes or the like can also work. Click it with the eyedropper in a program like LR3 and it will adjust RGB to be the same value. It can help, then you need to tweak.
I shoot everything RAW and use a target (WhiBal) when appropriate and possible. JPEG is lossy and any correction continues to degrade the image.
MS PHOTO wrote:
Thanks for the info, when I use AWB all of the faces look cold.
If you have mixed lighting in the photo then you can't get a global white balance.
For instance, if you're using flash in a room lit by incandescent bulbs and you expose such that the incandescent light is visable (i.e. you didn't nuke the room with flash) then you will have 2 different light colors in the picture. The light from the flash is going to be much bluer than the room lighting. If you adjust the face to look natural, the room will get very orange. If you adjust the room to look natural, the face will be very blue.
You can use gels to get the flash to match ambient so that you don't have this issue.
I'm not a professional...far from it. I shoot a lot of outdoor soccer pics, and various times of day have the obvious differences in white balance. I don't have a gray or white standard to shoot on location, but I find a simple improvisation works quite well.
I find anything at the location that should be white; a jersey, t-shirt, building, etc. On my D300s I set the WB to custom and snap a pic of the white object. Can't say its perfect, but 99% of the time I don't have to mess with WB in post.
If using flash as main then set the WB after you adjusted for exposure and ambiant mix ( if you allow any).
Same if you are going to use flash as fill. Get the exposure then set the WB and you will have very consistant results.
I use the ColorChecker Passport and try (to remember) to shoot the card before captures. I will shoot the grey card first then set custom balance in camera both in the studio and outdoors.
What is your trusted baseline for the "correct" color? For most it is a calibrated monitor and their eyes. But what if the calibration of the monitor is off? How will you ever know it?
One way is to use Custom WB in the camera off a gray card as a trusted baseline for color "by the numbers". The camera is the source of your color. If you set Custom WB off a gray card it will be technically correct (i.e. R=G=B on the card image). The card and the face of the person holding it in a test shot taken with the Custom WB should look perfectly neutral on the monitor. If not it will tell you something is amiss with the monitor calibration.
If you use Custom WB from a known neutral gray card you will find you don't need to mess around with the color balance much during editing. If you capture an image with a full range of detail from shadow to highlight and neutral WB there is very little you need to do in a technical sense to reproduce the scene accurately on the monitor or a printer, assuming you have an accurate profile for the paper being used. The print will not match the monitor, but both the monitor and the print should have neutral WB and a full range of tone with saturations to the physical limits of their respective gamuts. That is after all how the color management process is engineered to work.
More importantly by setting Custom WB you will have a consistent baseline across all the shots taking in the same lighting. By comparison, because AWB is set on each frame based on content there is no consistent WB baseline over all the frames making it impossible to reliably batch correct the files during editing.
Neutral WB off a gray card while technically correct is seldom the most pleasing or appropriate color perceptually. For example if all the other clues in the photo say it was taken at mid-day then neutral WB will look "normal". But if the shadow clues tell the viewer it is late in the day and the sun is setting neutral WB will look unnaturally cool. By capturing from the neutral baseline, or just having a portrait subject hold a gray card next to their face in a test shot, you can make the decision about how much to warm it up in the editing stage when you can see the results visually on the monitor. Color bias is also a means to convey mood and environmental conditions: summer scenes and most people shots look more natural with a slight warm bias, but in a winter scene you would expect a cooler bias to the lighting. I find it easier to make those judgements visually on monitor starting from known neutral baseline. YMMV
A typical workflow using Custom WB would be to start with a representative file from the batch, adjust it to taste visually from the neutral "by the numbers" trusted baseline for color, then copy / paste the adjusted color settings into all the other files in the batch.
When you can't set Custom WB before shooting the next best option for process control of color is to include a gray card in test shots in each new lighting situation. That's a good practice even if you set Custom WB because sometimes lighting conditions change or nearby object will create color casts you don't notice in person.
If you don't have time to shoot the gray card before capturing the action, shoot a test frame with the card in it during a pause in the action or before putting the camera away. Then during editing you can click correct on the card to get to the same "neutral by the numbers" starting baseline.
If you don't have a gray card handy use the preset closest to the dominant ambient lighting: Daylight, Tungsten, Fluorescent, or flash if you are using it. The color may not be correct at capture but it will be CONSISTENT across all the frames which will allow correcting one image based on content then batch copy/pasting the adjustment to the other files.
The least desirable from a process control standpoint is AWB.
Dealing with mixed lighting and green/magenta color biases
Color temperature shifts occur mostly along the blue/yellow axis which makes WB easy to correct in a RAW file. There is a wide range of color shift along the yellow/blue axis that will seem "normal" depending on the content and context clues in the photo. But In some cases like a portrait in open shade with a sunny background setting WB "normally" for the sunny background will make the skylight illuminated faces in the shadows look too cool. That's a situation where you'd want to set custom WB off the card held next to the face in the shade to "normalize" the most important content at capture. Then in editing you can decide to leave it neutral or perhaps warm it up a bit more by tweeking the color temp (yellow/blue) slider.
If you watch color balance in movies you will notice an overall green bias is often used to make skin tones look dull and monochromatic. But green / magenta biases in still photos nearly always look odd and unnatural because in most cases the viewer expects to see "normal" skin tones and reference colors. Shooting under trees creates a green bias to the lighting which is often not noticed in person because the brain adapts color perception to cancel it out. But if you were to shoot with the camera in Daylight WB it will record the green bias and make the lighting on skin look oddly dull and flat as is covered by a gray veil like in the movies. At the same time the green foliage accented by the green light looks great.
Here's how using Custom WB can help you spot and correct that type of green color bias problem. If you start with the camera set to Daylight WB outdoors then shoot the gray card, set Custom WB off that frame then shoot the card again, this is what you will see when toggling between the two frames on the playback...
Human perception being what it is, once you understand intellectually that the second frame on the right is the "correct" color because it was shot with a R=G=B technically neutral baseline off the gray card you will be able to see the heavy green bias in the ambient lighting by comparison. I always start with Daylight WB set on the camera when shooting the Custom WB shot so I will be able to see visually what color / tint the light is from the baseline of mid-day daylight. Just by setting Custom WB then shooting the card again I know what the color temp of the light is relative to mid-day sunlight and whether or not there is a green/magenta color bias problem.
Mixing flash and Custom WB of Ambient
Here's a caveat when using flash in the woods under greenish light: When Custom WB is used to eliminate the green the camera shifts WB toward magenta relative to the Daylight baseline. When you add flash relative to the adjusted WB the flash will be magenta and cooler relative to the adjusted WB creating a mixed lighting situation...
The background and shadows illuminated by the ambient will be neutral but the flash lit highlights created over the ambient fill will have a odd magenta/blue cast. During editing trying to remove the magenta color cast in the highlights will shift the neutral shadows toward green/yellow.
One solution to that technical WB dilemma is to use a reflector to bounce the same green but corrected light into the subject rather than using flash. It is technically possible to gel the flash green to match the ambient, but in practice is may be difficult to judge in the field exactly how much green to add to the flash to achieve a seamless match.
When shooting indoors with flash in tungsten environments flash can be gelled more predictably. For example if shooting stage presentations or rehearsals where flash is permitted I will gel my flashes with 1/2 CTO orange then set Custom WB off a gray card using the flash...
That results in the camera recording everything in the flash lit foreground from the technically neutral R=G=B baseline from the gelled flash. The 1/2 CTO may not be an exact match to the tungsten background, but its usually close enough to make the background look "normal". The advantage of gelling the flash in this way is it allows boosting the ISO of the camera and extending the range of the flash without introducing objectionable color casts. Boosting the ISO compensates for the loss of flash output from the gel.
Gelling flash to match fluorescent ambient lighting is more problematical because fluorescent lights come in a wide range of color temps and color rendering indexes (CRI) making it difficult to find the ideal gel color to use on the flash. When shooting under fluorescents I usually opt to use the Fluorescent WB preset and ambient only for wider shots, then for close-ups switch to ungelled flash (with Custom WB) and overpower the ambient with two flashes, sometimes adding a third flash to illuminate the background when necessary to avoid color casts from the room lighting.
Sources like Mercury-Vapor and Sodium lights are problematical for camera WB because they have spectrums which aren't well matched for photography.
There is no easy solution to mixed lighting situations. But Custom WB will, by comparison with a baseline Daylight WB shot used to set Custom WB shot, make you more aware of when there are color biases caused by time of day, artificial sources or light reflecting off of colored surfaces. Spotting and avoiding those mixed lighting problems at capture will eliminate most of the color editing headaches.
Again, understand that Custom Neutral WB set off a gray card isn't the best color, it simply provides a consistent baseline you can trust for objective evaluation of where you want the color to wind up in the final edit. More importantly it allows the convenience of batch correction across all the files of the session.
My images look a little cold with AWB, 