How white balance works in camera?

[Vesku]

There are at least 3 ways to set WB.

-Full auto WB

-Choosing kelvin degree manually

-Using (exposing) gray card and saving a WB preset

Can I get the same result with manual kelvin degree than using auto WB or gray card? Does the camera AWB make additional adjustments for image color like green-red or blue-yellow adjustments so that it is impossible to get as good result by just setting manual kelvin degree. 

It is important to get right WB in video in the first place. It is also disturbing if the WB changes rapidly during a clip. A WB-lock would be nice if using AWB.

[hyalinejim]

Kelvin lets you adjust blue to orange only, and not magenta to green. I get WB close to what I want in camera using any of the WB methods and then fine tune both color axes in post.

[mercer]

Lately, I've only been using Kelvin at 4400 and then adjusting accordingly in post.

[scotchtape]

Depends on your camera.  Many cameras can set K value and G/M shift.  

Also, in AWB on some cameras you can also specify whether you want want to push warmer/cooler and G/M shift (like Panasonic)

[Vesku]

I am curious if the AWB does other adjustments than plain kelvin adjust?

When taking RAW photos (Panasonic) and using the camera AWB in Lightroom or ACR it contains kelvin degree and additional color shifts.

[Andrew Reid]

3 hours ago, mercer said:

Lately, I've only been using Kelvin at 4400 and then adjusting accordingly in post.

Doesn't this hurt the image at 2500k and 8000k?

For example under candle light for the former.

And cloud cover for the latter.

It would be good to show some examples of what you're doing, and for us to see if it works or not or whether it is too big a compromise to image quality and colour.

Maybe with 10bit ProRes you can get away with a bit more adjustment in post but a full 4000k difference in white balance is nuts... you're not shooting RAW

[Matthew19]

3 hours ago, Vesku said:

There are at least 3 ways to set WB.

-Full auto WB

-Choosing kelvin degree manually

-Using (exposing) gray card and saving a WB preset

Can I get the same result with manual kelvin degree than using auto WB or gray card? Does the camera AWB make additional adjustments for image color like green-red or blue-yellow adjustments so that it is impossible to get as good result by just setting manual kelvin degree. 

It is important to get right WB in video in the first place. It is also disturbing if the WB changes rapidly during a clip. A WB-lock would be nice if using AWB.

3

Custom white balance does (at least with Canon and Sony) adjust for green and magenta. Magic Lantern did a great job of showing you these adjustments with its custom WB feature. Sony shows them to you as well. Canon doesn't tell you a thing. After using this for a while, I'm surprised to see how often green needs to be removed because of indoor window tint or bounce grass.

[Cary Knoop]

3 hours ago, mercer said:

Lately, I've only been using Kelvin at 4400 and then adjusting accordingly in post.

I don't think that is a good idea. 

It is far better to set an accurate white balance directly from the sensor data than to set it after the information is debayered, chroma subsampled, noise reduced, anti aliased, sharpened and compressed.

 

[jonpais]

Wih the Panasonic GH4, I always set WB manually using the color grid thingy. Since I almost always shoot outdoors, I'd point the camera at the pavement, being sure to include a bit of my pant leg, a tree or something and adjust till things looked good. Then I'd go ahead and shoot some people, and if the color looked okay when I got home and viewed them on the computer,  I'd assign that setting to one of the custom dials. I did this for bright and overcast light as well as for with and without  ND filters. When going out to shoot, I'd just select the custom setting for that situation.

With the X-T2, I'm liking the AWB so far, but I haven't tried putting an ND filter on yet to see how the color meter behaves.

If color balance is off in my clips, it takes me forever doing color correction, so if the XT2 gets AWB right, I will be a happy camper. 

[mercer]

1 hour ago, Andrew Reid said:

Doesn't this hurt the image at 2500k and 8000k?

For example under candle light for the former.

And cloud cover for the latter.

It would be good to show some examples of what you're doing, and for us to see if it works or not or whether it is too big a compromise to image quality and colour.

Maybe with 10bit ProRes you can get away with a bit more adjustment in post but a full 4000k difference in white balance is nuts... you're not shooting RAW

I wouldn't do it if I was shooting under candlelight but for a generic wb, I find it better than auto in a lot of instances and it helps with mixed lighting indoors... sunlight coming through a window and a tungsten lamp. 

This is a long boring 120fps slog2 shot from the Rx100v where I used 4400. It's my first attempt at slog2, so don't be too harsh...

 

Also, I don't know if anyone has used it, but Colorista IV has a "Guided Color Correction" feature and the feature turns a 5 minute correction process into 30 seconds. I highly recommend it. 

[hyalinejim]

1 hour ago, Andrew Reid said:

Doesn't this hurt the image at 2500k and 8000k?

For example under candle light for the former.

And cloud cover for the latter.

 

1 hour ago, Cary Knoop said:

I don't think that is a good idea. 

It is far better to set an accurate white balance directly from the sensor data than to set it after the information is debayered, chroma subsampled, noise reduced, anti aliased, sharpened and compressed.

 

It depends on what you consider an accurate WB to be. If I had to choose a WB that my camera would be stuck on forever, I'd choose 4500. This will make tungsten look warm and shade look cool, as they should be. In my opinion, a custom WB in these situations leads to unnaturally clinical colour in tungsten light and unnaturally warm colour in shade.

I'm not suggesting leaving your camera on 4400 for the rest of your life. But it's actually not as bad as you might think. And the Kelvin scale is not linear. The jump from 3000 to 4000 is very noticeable, while going from 7000 to 8000 is relatively subtle. So 4400 is not as far from 8000 as you might think from looking at the numbers.

Before I shot RAW on my 5d3 I would usually begin from 4500 and dial up or down depending on my intention for that scene. On my XC10 I leave it on cloudy all the time (as colour seems nicer with this preset although I've no hard proof of that) and the 422 codec is tough enough for me to bring it into the correct range, even when shooting tungsten.

I should mention that I use the now defunct GingerHDR Color Temperature plugin, though. This is way better than anything else I've tried. 

[mercer]

Here's another example where I used 4400 Kelvin WB with the GX85...

 

[Don Kotlos]

Using a set  WB and adjusting in post with an 8bit codec is a very bad practice for the following reasons:

1. With 8bits per channel you loose a lot of color information, that upon correction will give you flat colors with minimal tonal differences (skin will look like plastic) and a lot of banding (but interestingly at least in theory you could get less sky banding if you shift your WB to cooler values, just don't have a face in the scene  ) 

2. The sensor itself is not equally sensitive across the visible spectrum, consequently the colors will shift to different hues

3. Artificial lights have non-uniform spectra (fluorescent bulbs is the most extreme) and that will amplify the hue differences and flatter tonalities.

Adjusting the WB in post to bring back the warmness or coolness of the scene will always give you a better result. 

Forgetting the WB in one setting might sound easier, but it is a bad practice that will definitely give you more problems. 

Going back to the main thread subject, any natural light (daylight, shade, clouds) is easy and can be a set value of temperature & tint for each. Artificial lights always need custom adjustments in both temperature and tint, and never ever AWB (at least with Sony cameras). 

[mercer]

1 hour ago, Don Kotlos said:

Using a set  WB and adjusting in post with an 8bit codec is a very bad practice for the following reasons:

1. With 8bits per channel you loose a lot of color information, that upon correction will give you flat colors with minimal tonal differences (skin will look like plastic) and a lot of banding (but interestingly at least in theory you could get less sky banding if you shift your WB to cooler values, just don't have a face in the scene  ) 

2. The sensor itself is not equally sensitive across the visible spectrum, consequently the colors will shift to different hues

3. Artificial lights have non-uniform spectra (fluorescent bulbs is the most extreme) and that will amplify the hue differences and flatter tonalities.

Adjusting the WB in post to bring back the warmness or coolness of the scene will always give you a better result. 

Forgetting the WB in one setting might sound easier, but it is a bad practice that will definitely give you more problems. 

Going back to the main thread subject, any natural light (daylight, shade, clouds) is easy and can be a set value of temperature & tint for each. Artificial lights always need custom adjustments in both temperature and tint, and never ever AWB (at least with Sony cameras). 

By no means am I suggesting this median approach is the best or proper way to handle white balance, but when I was setting WB at 5600 or 3200, more often than not I was adjusting down to 5000 or up to 3800 in post... respectively. By setting a median number I have found that I was able to set it and forget it. I look at it as a Kelvin AWB. YMMV.

[Damphousse]

9 hours ago, Vesku said:

There are at least 3 ways to set WB.

-Full auto WB

-Choosing kelvin degree manually

-Using (exposing) gray card and saving a WB preset

Can I get the same result with manual kelvin degree than using auto WB or gray card? Does the camera AWB make additional adjustments for image color like green-red or blue-yellow adjustments so that it is impossible to get as good result by just setting manual kelvin degree. 

It is important to get right WB in video in the first place. It is also disturbing if the WB changes rapidly during a clip. A WB-lock would be nice if using AWB.

From your post I guess we are to assume you either only shoot under very controlled studio lighting or only when natural lighting is the least interesting.

As with the auto exposure thread all these things are tools.  There simply is no rule about one being better than the other or using one vs the other all the time.  Frankly if you are going to use one all the time better to learn how to use manual white balance because a) there are cameras that don't have AWB b) you can use manual white balance in all those instances where lighting is actually interesting.

The laws of physics dictate that you will not be able to use AWB most of the time... assuming you are the kind of person that likes to shoot under interesting light.  So worrying about GR adjustment is moot.  The Kelvin you set manually will be a million times better looking that whatever the dumb computer comes up with regardless of how many adjustments it makes.  Computers can't make artistic decisions.

And you need to learn your equipment.  Cameras are different.  My BMPCC doesn't have AWB.  And it doesn't have a gray card WB.  It does have a color card color adjustment that you can do in post with Resolve.  And Magic Lantern's white balance doesn't need a "WB-lock".  You point the camera at a gray card or scene and press a button.  It takes a couple of seconds to analyze what it is looking at and comes up with a WB.  It doesn't change WB unless you tell it to sample again.  You are asking questions and making commentary on a broad category and there simply is no one answer.

 

58 minutes ago, Don Kotlos said:

Using a set  WB and adjusting in post with an 8bit codec is a very bad practice for the following reasons:

 

Yeah, shoving thin 8 bit footage around because you intentionally botched WB is a bad idea.  WB that stuff, toss a LUT on it and do some further grading and it is artifact city.

6 hours ago, Matthew19 said:

Custom white balance does (at least with Canon and Sony) adjust for green and magenta. Magic Lantern did a great job of showing you these adjustments with its custom WB feature. Sony shows them to you as well. Canon doesn't tell you a thing. After using this for a while, I'm surprised to see how often green needs to be removed because of indoor window tint or bounce grass.

Magic Lantern is awesome.  I used AWB a lot.  I would just give it a whirl by pointing it at a scene.  If it looked good I rolled with it.  Didn't even use a gray card most of the time... out of sheer laziness.

 

[Vesku]

I wonder if I have opened another Pandora's box and soon it will be closed.

My question/assumption is that the plain manual kelvin adjustment is not as accurate as AWB or WB set by gray card because it is not balancing image color completely using RGB color correction. My experience is that usually I can get better white balance with AWB than with manual kelvin adjustment. A WB-lock would be good with AWB.

AWB fails in some situations for example if a person with blue shirt comes in image.

[Eric Calabros]

I think Nikon applies different color curves in different WB ranges (maybe Canon is doing similar thing too). We don't know these curves well and where exactly they come into play. they intentionally shift some hues as WB changes, to make the image look Ok. so AWB in these cameras is not just about accuracy. 

[Vesku]

13 minutes ago, Eric Calabros said:

I think Nikon applies different color curves in different WB ranges (maybe Canon is doing similar thing too). We don't know these curves well and where exactly they come into play. they intentionally shift some hues as WB changes, to make the image look Ok. so AWB in these cameras is not just about accuracy. 

Panasonic GH4 video exif shows WB kelvin degree and shifted values for red, green and blue (RGB). With AWB the kelvin degree may be the same while RGB values changes between slightly different scenes.

[Damphousse]

7 hours ago, Vesku said:

I wonder if I have opened another Pandora's box and soon it will be closed.

My question/assumption is that the plain manual kelvin adjustment is not as accurate as AWB or WB set by gray card because it is not balancing image color completely using RGB color correction. My experience is that usually I can get better white balance with AWB than with manual kelvin adjustment. A WB-lock would be good with AWB.

AWB fails in some situations for example if a person with blue shirt comes in image.

Well your "experience" does not include shooting under interesting lighting conditions.  Which is fine but be upfront about that.  I realize you like backsolving into this auto everything idea and that is fine.  It's a free country.  You can shoot with the lens cap on if you want.  My post isn't to convince you.  You have already made up your mind.  I am just posting in case any other noobs come along and wonder why a wonderful looking scene they shot looks like garbage when they get home.

One thing I learned with photography as my skills progressed is to seek out interesting light and to know how to handle it.  Now when I go on vacation I get up even earlier than when I am at work and I miss happy hour in the evening.  I go out and shoot during the "golden hour" so I don't end up going home with a bunch of crappy vacation snapshots.  You simply can't use AWB during the golden hour.  It totally defeats the purpose.  The shape and quantity of the shadows is still nice but AWB screws up the colors.

Worrying about RG adjustment when your Kelvin is totally off makes no sense.

I wish my BMPCC had custom WB option for those times I am shooting at high noon.  It would be nice because it would take into account the color casts imparted by my variable ND, UV filter, and whatever lens I am using.  The BMPCC codec is robust enough to handle a lot of adjustments in post but I would rather not have to do the adjustments to begin with.  And yes I have seen people on the internet lambast anyone who wants custom white balance on a "professional" camera like the BMPCC.  I simply don't understand why people want to push either all manual or all auto.  Don't people use their cameras in a variety of settings and realize all this stuff comes in handy quite a bit?

[Vesku]

I think using a gray card method in "interesting light" gives too neutral or "pure white" result. What is the right method to capture "golden hour" or other interesting scenes? Is it best to rely on screen or EVF or is it best to know by experience what kelvin degree suits best for the wanted result.

AWB in Panasonic is not making images too neutral indoors or in colored lights. Gray card makes much more neutralizing.