JPEG White Balance

xendless xurbia

Hello all,

I know the first thing that will be mentioned is "shoot RAW". Well I normally, do, but I had a very very last minute invite the a Hockey Practice, and used the fluorecent WB setting on my D70s. Now when I got home, and downloaded the files to my HD, I noticed there was a very yellow and sometimes green hue on my photo's. Now I'm no expert when it comes to color correction, but what I'd like to ask is the following.

What steps do I need to take to correct these "wrong" settings for WB?

Should I use LAB, and pull the B curves top right in until the yellow hue dissapears? Same with the A's lower left in until the green hue dissapears?

or

Select a white and black point in the Threshold dialog box, and work from there?


Thanks :scratch

BinaryFx

It may be image dependent on what gives best results. LAB is great for big moves, so if there is a severe cast, then perhaps LAB would be a good starting point, but as the image starts in RGB I would generally prefer to work there first. I would start with setting neutral endpoints and a known neutral midtone or other objects that are known/presumed neutral. This is all done in RGB with a color blend curve. One can then move to LAB if needed. One would need to compare the two approaches to see what was best for the image at hand (starting in RGB before going to LAB vs. going to LAB first before finishing off with RGB edits).

One could also see how the white balance control in current versions of ACR/ALR compare to Photoshop edits on the JPG.

The basics are to look for known colours and to alter their numbers to be provide a more pleasing response, if they are found wanting. If you can post an image that may help.


Hope this helps,

Stephen Marsh.
http://members.ozemail.com.au/~binaryfx/

jfriend

xendless xurbia wrote:

Hello all,

I know the first thing that will be mentioned is "shoot RAW". Well I normally, do, but I had a very very last minute invite the a Hockey Practice, and used the fluorecent WB setting on my D70s. Now when I got home, and downloaded the files to my HD, I noticed there was a very yellow and sometimes green hue on my photo's. Now I'm no expert when it comes to color correction, but what I'd like to ask is the following.

What steps do I need to take to correct these "wrong" settings for WB?

Should I use LAB, and pull the B curves top right in until the yellow hue dissapears? Same with the A's lower left in until the green hue dissapears?

or

Select a white and black point in the Threshold dialog box, and work from there?


Thanks

Gives us a link to some of the photos and I'm sure you'll get some more specific help. I nearly always do color correction in RGB, not LAB.

The key for me is to find something in the image that is supposed to be neutral (white, gray or black) or is of a known color. I then put color samplers on those so I can continuously see their colors. I then create a curve adjustment layer and tweak the individual color channel curves until the color sampler points move to the expected values. Ideally, you'd find a black neutral, a highlight neutral and some sort of mid-tone neutral.

kirbinster

I use Adobe Lightroom for this, it does a great job letting you adjust the whitebalance even in jpeg files.

xendless xurbia wrote:

Hello all,

I know the first thing that will be mentioned is "shoot RAW". Well I normally, do, but I had a very very last minute invite the a Hockey Practice, and used the fluorecent WB setting on my D70s. Now when I got home, and downloaded the files to my HD, I noticed there was a very yellow and sometimes green hue on my photo's. Now I'm no expert when it comes to color correction, but what I'd like to ask is the following.

What steps do I need to take to correct these "wrong" settings for WB?

Should I use LAB, and pull the B curves top right in until the yellow hue dissapears? Same with the A's lower left in until the green hue dissapears?

or

Select a white and black point in the Threshold dialog box, and work from there?


Thanks

arodney

On a rendered image, that's a tough one compared to Raw. I will say that while the controls in Lightroom are vastly more useful on Raw, its worth a try on a JPEG or rendered image. The advantages to me are speed, virtual copies (variations) without any speed or file size over head. The HSL controls are great and don't over look using the Split Tone controls and Vibrance in a minus direction.

The downside is (and the jury is out) converting to a wide gamut linear color space to now do the processing. But this may be far less damaging than going into and out of Lab, certainly faster. You'll have some advantages and disadvantages handling the tonal levels depending on where the big problems are. You can always render out a variation that's 90% where you want to be, then use Photoshops local correction tools where it is best addressed.

I had a situation where someone took my 5D to shoot me getting an award. I didn't notice he had set the camera to shot JPEG, all under high ISO and mixed but mostly tungsten lighting. Pretty ugly. The Raws I shot under the same scene were a piece of cake to render. The JPEGs not so easy but, no question the results were superior to the originals (but get it right in the Raw, so much easier and better results).

xendless xurbia

jfriend wrote:

Gives us a link to some of the photos and I'm sure you'll get some more specific help. I nearly always do color correction in RGB, not LAB.

The key for me is to find something in the image that is supposed to be neutral (white, gray or black) or is of a known color. I then put color samplers on those so I can continuously see their colors. I then create a curve adjustment layer and tweak the individual color channel curves until the color sampler points move to the expected values. Ideally, you'd find a black neutral, a highlight neutral and some sort of mid-tone neutral.

Thanks to all of you for your replies. Greatly appreciated.

So basically, set the black and white point, and then work the R G and B curves seperatly to fine tune the WB. Is that correct?

I'm still running CS2, and I hope for an upgrade to CS3 next week (if finances are in place).

I'll give you a comparison between yesterday and today.

Sept 14th - Shot in JPEG using Flash WB on the D70s.
http://farm2.static.flickr.com/1253/1381310251_55af81be33_o.jpg

Sept 15th - Shot in RAW using Fluorecent WB on D70s.
http://farm2.static.flickr.com/1008/1388096918_dda78d1905_o.jpg

Please excuse the image quality. I shot on a very crappy Sigma 70-300mm lense at ISO 1600 at f5.

Now we can see the marked difference in WB quality here. I'm so used to using the WB Eye Dropper and plotting it on a grey or white point in the image and working from there. But with JPEG's, I'm totally lost.

BinaryFx

xendless xurbia wrote:

Thanks to all of you for your replies. Greatly appreciated.

So basically, set the black and white point, and then work the R G and B curves seperatly to fine tune the WB. Is that correct?

<snip>

Now we can see the marked difference in WB quality here. I'm so used to using the WB Eye Dropper and plotting it on a grey or white point in the image and working from there. But with JPEG's, I'm totally lost.

There is no argument from me that white balance should ideally be set correctly in the camera, or the raw converter. That being said, all is not lost if the wrong WB setting is baked into the JPG during the in-camera rendering process (mileage may vary depending on the image and lighting conditions). Perhaps WB should not be used to describe the process, once the file is a rendered image (as WB is technically a camera/raw processing term).

As previously mentioned, one can try ACR/ALR which now offer the ability to process rendered images. In Photoshop working on the rendered image, there are many ways to deal with colour casts.

My quick and dirty workflow suggestion would be as follows. Before using curves, one could try one of the simulations of traditional camera filters - or a Photo Filter adjustment layer, in this case a cooling filter 80 preset. One would place one or more colour samplers on the ice, clothing etc which should be neutral. When adjusting the photo filter or curves, one is aiming to get close to R=G=B values or zero AB LAB values. Taking things to the next level, the basic process is to set neutral endpoints and remove casts from other known colours, this being a global move with levels or better yet, curves. One can set the curves adjustment layer to color blend mode so that luminosity is not adversely affected by the edits.

The cast correction process starts with numerical inspection of the image. One may have visually decided that the image has a cast, but that only takes one so far. The info palette is the key to the inspection of the image. It is helpful to know what type of issue one is facing, if there are single or multiple casts (different hue in the shadow to the highlights), or if the cast is more intense in certain areas etc. I find that the info palette set to provide LAB readings helps a great deal, as in LAB the AB channels hold colour (A: positive values = magenta, negative values = green | B: positive values = yellow, negative values = blue). Zero values for AB in LAB are neutral/gray. The higher the value the more intense the hue. When inspecting or correcting an image, I will often have the info palette and fixed samplers in the document color mode (RGB, CMYK) and also in LAB.

Once one knows the issues at hand, informed edits can be made.

The basics are to start with a neutral white and black point, if appropriate. One should also find other neutral tones, be they mid tones or other tones. Other known/presumed hues can also be inspected to see if they have a cast. Colour samplers are placed (found under the eyedropper tool) on key points to note via the info palette what is taking place when correcting the image. This is both a numerical and visual editing process but one can do it with only the info palette if required. Sometimes the image looks better with a slight cast than when perfectly neutral, so it is often subjective (what is more important when it comes to neutrals, the clothing, the ice, or both?).

Beginners will benefit from using the three curves eyedroppers to set appropriate white/black/neutral midtone points - but this is not as good as manually shaping the curve and I recommend that they learn to do without this crutch as soon as possible (sure it is fast, but quality is often more important, if not, then simply use a photo filter adjustment and or the three eyedroppers in curves).

Anyway, one can read an entire free chapter on the basics of inspecting and correcting basic colour issues as presented in this topic in the following PDF:

http://www.ledet.com/margulis/PP7_Ch02_ByTheNumbers.pdf
http://www.ledet.com/margulis/

Below I have attached an example of RGB edits. I used a curves adjustment layer set to Color blend mode. I shaped the endpoints and intermediate points on the curve in each individual channel, until the fixed colour samplers for the key tones were neutral. No selections, history brush or masks etc were used in this global correction. If one is after an even more clinical (neutral) appearance than these quick basic curves, it is a fairly fast and simple task to isolate the lighter near neutral image tones and neutralize them.


Regards,

Stephen Marsh.
http://members.ozemail.com.au/~binaryfx/

Duffy Pratt

Here's a version quickly corrected in LAB, adjusting the B channel only. I moved the curve 14 points to the left (dropping the top point 14 points and sliding the bottom point to the right 14 points). Then I slightly moved up the middle point to pull a little blue out of the jerseys.

Duffy

BinaryFx

Duffy Pratt wrote:

Here's a version quickly corrected in LAB, adjusting the B channel only. I moved the curve 14 points to the left (dropping the top point 14 points and sliding the bottom point to the right 14 points). Then I slightly moved up the middle point to pull a little blue out of the jerseys.

Duffy

Duffy, it is amazing what a fast move in LAB can do, even if to only one channel!

The following is not criticism, just notes on inspecting your edits for us all to learn from (the same can be done for my image). As you did not adjust the A channel, the image is still slightly green.

I notice that you were more conservative with your B channel adjustments than I was with my separate RGB color blend curves, as your version is less yellow than the original - but not as neutral as my version. Both LAB and CMYK (or RGB) values indicate yellow in the ice and clothing. Your correction is roughly halfway between the two extremes of the original and my correction.

As I mentioned earlier, this may be a subjective process and a version that is not neutral may be preferred. In the case of ice/snow, I personally think it is safer to bias things on the cool side (negative AB values), than the warm side (positive AB values), if one is not going for a fully neutral look.

In all cases, the original or both simple corrections so far, the jersey and ice need more separation between them. In a different correction (this time addressing luminance and not colour), I would engineer more luminosity variation between the ice and jersey on the right hand side.


Regards,

Stephen Marsh.
http://members.ozemail.com.au/~binaryfx/

davev

Depending on the shot, and what you're doing with it, the easy way is to use "Remove color cast"

Just click on something white.
Is this perfect? No. Is it fast and easy? Yes.

Good luck.

pathfinder

Dave,
Was the background behind the child, gray or brown, This was shot with flash or tungsten lighting?

I agree that finding a true neutral and using the white balance eye dropper in ARC is the fastest and the simplest. Perhaps, not always the very best though.

xendless xurbia

I found this tutorial on Youtube, and it seems to go along the lines of what you guys are saying.

http://youtube.com/watch?v=pvjbbOeUQ1Y

I applied it, and it worked on those pics I was having issues with.