White Balance - Adjust via RGB histogram

Well, interesting Corey, it's obviously an improvement. What method did you use to match the curves?

PixelMagic wrote in post #11742522
Sigh...this doesn't even begin to make sense to me. If you're shooting in a controlled environment (studio), what's stopping you from simply making a reference shot by inserting a ColorChecker card into the scene? You'd get white balance much faster (one click on a neutral patch) that way than futzing around with the Temp and Tint sliders.

I don't have a color checker card. I probably will in the future. For now, what I'm doing probably doesn't make sense, but I thought I'd post it anyways. Seems to be working for me.

tonylong wrote in post #11742535
Well, interesting Corey, it's obviously an improvement. What method did you use to match the curves?

Just adjust the temperture until the curves match more or less and then fine tune with the tint to match them up even better.

I picked up this method on Lynda.com from one of there tutorials. I have used it before and found some success with it. Sometimes it doesn't work and will have to go into curves. I try to stay away from auto correction for now because you cant learn technique and principles of a correction by a one click.

I guess it works for you if you're willing to argue that you aren't shifting colors or introducing color casts in the other parts of the photo (see the blues in your example photo).

There are lots of other ways to get accurate white balance without buying a ColorChecker. For starters you can set the in-camera WB preset to the prevailing light conditions instead of Auto WB. You can also set a Custom WB in-camera by shooting a sheet of paper in the same light as your subject and setting your camera to use that photo as your WB reference. While both of these methods are still inexact they will be more accurate that what you're currently doing.

Hardcore wrote in post #11742566
I don't have a color checker card. I probably will in the future. For now, what I'm doing probably doesn't make sense, but I thought I'd post it anyways. Seems to be working for me.


Just adjust the temperture until the curves match more or less and then fine tune with the tint to match them up even better.

Hardcore wrote in post #11741884
I would have to think that indeed the rgb histogram has much to do with white balance. That is what you are adjusting when you are changing white balance.

What you are changing is the numbers that encode the pixel values. The histogram is merely one possible graphic display of those numbers, a graph of the number of image pixels at each tone value. An image is another way of displaying the same data.

I generally use the formula R220, G180, B160 or R86%, G70%, B63% (in sRGB) as a rule of thumb. Or to generalize it more instead of tying it to a particular brightness level, G is around 80% of R and B is 72% of R. In Lightroom you need to be a bit darker, 70%/63%/52%, because the conversion from Melissa RGB to sRGB will raise the numbers.

This is funny, because when developping DPP++, I was working on a function that allows to adjust the white balance automatically using exactly the same method. However after cheking the method on several kind of pics, I had noticed that eventhough it works very well on some kind of pics, however for other kind of pics it doesn't work well at all. So finally, I didn't include it in DPP++.
Here is an example of pics where it does'nt work.
. In the first pic I have adjusted the color temperature so as the red green and blue histograms overlap as much as possible. The white balance here is not good.
. In the second pic, the white balance is better eventhough the red green and blue histogram don't overlap.

I have also noticed that the color temperature slider acts mainly on the red and blue histogram positions while the tint slider acts more on the green histogram position. Pics 3 and 4 shows the same pics but only with red and blue histograms.

PixelMagic wrote in post #11742598
I guess it works for you if you're willing to argue that you aren't shifting colors or introducing color casts in the other parts of the photo (see the blues in your example photo).

There are lots of other ways to get accurate white balance without buying a ColorChecker. For starters you can set the in-camera WB preset to the prevailing light conditions instead of Auto WB. You can also set a Custom WB in-camera by shooting a sheet of paper in the same light as your subject and setting your camera to use that photo as your WB reference. While both of these methods are still inexact they will be more accurate that what you're currently doing.

Understood and I will try those techniques you mentioned. As for the photo I posted. The colors are much more accurate on the version I corrected. The blue is much more accurate. The blanket is actually a grey like you see in the corrected version and not blue.

Also, there was no preset white balance setting that came close to the 11457 I had to set in temperature and the +19 for the tint.

Yeah, I'd expect things to be off in a lot of scenes. It's interesting, because Corey did get an improvement using his method, but it was obvious he had a blue tint in the original image -- he said it was from an ND filter. So in that type of situation pulling back the blue curve to match the R and G would certainly make things better. But your pics above show that it isn't a "cure all" but only for correcting an obvious tint, I guess.

I find the white Balance in picture #3 is the best on my monitor.

#1 is too blue
#2 is too red/orange
#3 is pretty good! Could be a tad warmer.
#4 is too red/orage

Of course, that is on my monitor and it is only calibrated with a spyder 3 express.

tonylong wrote in post #11742697
Yeah, I'd expect things to be off in a lot of scenes. It's interesting, because Corey did get an improvement using his method, but it was obvious he had a blue tint in the original image -- he said it was from an ND filter. So in that type of situation pulling back the blue curve to match the R and G would certainly make things better. But your pics above show that it isn't a "cure all" but only for correcting an obvious tint, I guess.

No, not from an ND filter. The picture I posted was natural light. I just learned to use this technique from trying to get rid of color casts on my nd filters.

#1 and 3 are the same pic
#2 and 4 are the same pic
the difference is just that the green channel is not displayed in the histogram

Hardcore wrote in post #11742710
I find the white Balance in picture #3 is the best on my monitor.

#1 is too blue
#2 is too red/orange
#3 is pretty good! Could be a tad warmer.
#4 is too red/orage

Of course, that is on my monitor and it is only calibrated with a spyder 3 express.

Hardcore wrote in post #11742716
No, not from an ND filter. The picture I posted was natural light. I just learned to use this technique from trying to get rid of color casts on my nd filters.

Where do you think the blue cast came from? That seems to be the key to the correction.

tonylong wrote in post #11743127
Where do you think the blue cast came from? That seems to be the key to the correction.

The blue cast came from outside as it was natural light. The snow, winter and a setting sun probably had some impact on the color.

This technique works well though for removing a magenta color cast from my nd filters as well.

PixelMagic wrote in post #11742598
There are lots of other ways to get accurate white balance without buying a ColorChecker. For starters you can set the in-camera WB preset to the prevailing light conditions instead of Auto WB. You can also set a Custom WB in-camera by shooting a sheet of paper in the same light as your subject and setting your camera to use that photo as your WB reference. While both of these methods are still inexact they will be more accurate that what you're currently doing.

Paper isn't a good source for accurate WB, as it will also have color.
Proper WB needs to be accurate and only a true spectral 18% gray will give that.
The Whi-Bal cards are the only cards, I know of that are calibrated for a true 18% gray. Therefore rendering proper WB from the lighting it's used with.

Everything else is a guess at best.

drdiesel1 wrote in post #11743433
Paper isn't a good source for accurate WB, as it will also have color.
Proper WB needs to be accurate and only a true spectral 18% gray will give that.
The Whi-Bal cards are the only cards, I know of that are calibrated for a true 18% gray. Therefore rendering proper WB from the lighting it's used with.

Everything else is a guess at best.

Not true. Whi-Bals are neutral grey but they are not 18%. And the tone has nothing to do with WB. 18% cards were used for calculating exposure of film and continue to be used for this purpose today even though digital cameras are calibrated to 12-13% and an accurate exposure from an 18% card would require an EC of +1/2 - 2/3 of a stop. WB can be calculated from any grey tone, including white, as long as it is truly neutral.