White balance spot – even if white area is really small?

Hi,


sometimes I get in trouble, when I try to use the „white balance spot” to improve some of my photos. For photos with buildings this works out fine, typically. But I´m not very successful with images without bigger white areas. Now someone may ask, why I do not use another method to get rid of color casts. The point just is that the “white balance spot method” corrects even pictures where I would never imagine a color cast. So, I have the impression that this is a very precise method. I really like it. But how can I reach reasonable results for pictures let´s say landscapes with a majority of green color, without big white areas, but maybe just very small white “points”? When I just play around with the spot, I´m very unsure if the result really is reasonable, because I can´t tell exactly if the point where I´m using it, is “really” white. Maybe you can give me a hint.


Regards,
Ben

Hi Ben,

The most accurate way for gray/white balance is using a 18% gray card. However the gray card is not always available, so manual white balance is required, e.g. "White balance spot". As this his method is highly subjective and relies a lot on your perception, a color calibrated screen is very recommended. In order to get good color balance, either a gray or white point must be selected. If you cannot choose the right point due to small area, zooming in would be a good possibility. By zooming to >600% (6-9 on your keyboard) you will even see the pixels, making it much easier to select the correct white/gray point.

Please note that due to color cast, a white area will not appear white on your screen prior white balancing. Just choose a spot/area, which should white or gray in REALITY. For example, eye's white, white shirt etc... Asphalted street is also very useable and comes very near to a 18% gray.

Hope this helps

Hoang-Tran

if I can use white balance even with gray spots (since all you need is the absence of any kind of color in that spot in reality), does that mean I could also use a black spot to get rid of any kind of color cast by using the white balance function?

And what would be the advantage to using an 18% gray spot? Does the function white balance work better with that gray than with any other kind of white or gray?

cheers,
PhotoWebber

Hi,

AFAIR there was also "black-balance" = using black as reference color. Some older devices offered that option. But this is not that common and IMO not effective, as true black (RGB = 0,0,0) is mostly unaffected by color cast.

What you need is a "neutral" color. Useful "neutral" color can either be gray or in a lesser instance white. Gray as a neutral color is your best bet, as it is spectrally neutral = equally reflects all colors. Its hue is also neutral. Thus most expensive cards for white balancing are gray cards (18%). They offer the most accurate white balance or should I say "gray" balance ;-)

White (RGB = 255,255,255) is a bit less suitable than gray but can be found almost in all photos, making it easier to perform white balancing even without a gray card. The disadvantage is that overblown area will also be displayed as white (255,255,255) as well. So if you use one of those spots for white balancing, the color cast will probably not removed.

Best regards

Hoang-Tran

P.S.: I forgot to mention that 18% gray card reflects 18% of the the incident light, exact the same as light meters work. This is also a huge advantage for gray card.

Hi Hoang-Tran,

Thank you for your substantial answer and good tips. I really understand now how to use white/gray balance in general and with PhotoPerfect.

One additional question regarding "gray card". If I understand your explanation correct, a gray card is really a "paper" card you can buy. But where and how would you use this card - just in a studio or even outside?

Regards,

Ben

Hi Ben,

You are welcome.

Yes, a gray card can either be made of paper, plastic etc... More important is that the material is non reflexive and of course the color = gray.

Personally I use gray in studios and in situations with different, mixed and complex (artificial) light sources. In these situation, the white balance of most cameras is not accurate enough for me or it takes too long to get it right.

Outside a gray card is mostly not necessary, as natural light has almost no color cast. Besides almost all cameras can handle natural light superbly.

In most cases however you can also just use a white sheet of paper as reference instead of the gray card. I would say the result would satified 95% of the users ;-)

Cheers

Hoang-Tran

OK - understood,

So, a gray card would be used in a studio typically. How would this work then on the practical side. Is it necessary to embed/show a grey card in every single picture - even, if there are no changes regarding the setup incl. the lighting? Or is there a chance to use the gray card just within the first photo and then, after the shooting, transfer the white/gray balance settings with PhotoPerfect to the other photos of this session?

Regards,

Ben

Hi, I would say, a gray card is useful for studio or for indoor situation with difficult (artificial) lighting, like e.g. party, weddings etc...


No, if the lighting condition does not change during the shooting, you only need 1 reference photo taken with the gray card. After that you can just use the batch process function in PhotoPerfect (Hotkey = F12) to apply the white balance adjustments done to the reference photo to the rest.

In order to do so, just open your reference photo, then select all to be processed photos in the thumbnail view and press F12 (or alternatively File-> Batch processing). After that please choose "Clolor Types -> White Balance". In the opening window, you can then use the "White balance spot" option to click on to the gray card. The corresponding parameters will be then saved to your batch file. If you are satisfied now, just save the batch file and/or apply it to the selected photos. They will all get the same treatment then ;-)

Best regards

Hoang-Tran

Hi,

That´s cool, I really like PhotoPerfect and I think I have buy a gray card now.

Thank you for this lesson Hoang-Tran ;-)

Regards,

Ben