Last week I was walking around NY City taking pictures with my D800E. Several of them included red traffic lights. However, in LR4 or CS5, they appear as yellow lights. I shot RAW and converted to JPEG for posting (below). No other adjustments were made. Camera white balance is set to Auto1. Any suggestions as to why the red traffic lights are not red?

Thanks!

Nick (Roxbury, Connecticut Nikonian)

Attachment #1, (jpg file)

Looks like blown highlights in at least one channel.

Larry - a Bay Area Nikonian
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Hi,

in raw format the camera white balance is not applied in Lightroom. In principle, you need to set the white balance yourself, although Lightroom most often does pretty good job of guessing it.

I also believe you have overexposed one of the color components.

Best regards,
Kari

Thank you for the helpful comments. Both of you are right. The red was overexposed. I've got to admit to some inexperience here. To learn more, I just went through more than 50 RAW images in LR from this particular shoot. Many were slightly overexposed. My exposure compensation was set to 0.0. I will change that to -0.3 and try again.

I also noticed that a number of my images were clipped at both ends of the spectrum in high contrast situations. I'll use the shadow and highlights slider to correct. However, in scenes such as this, is it better to properly expose the highlights and let the shadows fall where they may?

Nick (Roxbury, Connecticut Nikonian)

> However, in scenes
>such as this, is it better to properly expose the highlights
>and let the shadows fall where they may?
>
Shoot manual, spot meter the highlights to make sure they are withing your range. Otherwise, just set exposure comp and do trial and error until the histogram is not showing clipped highlights.

Mick
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As others have said the red channel is overexposed. I experienced something similar when I took a photo of my grandson with his first buck kill. He was wearing a blaze orange cap and even though sitting in open shade the cap photographed as bright yellow in every exposure. I didn't notice until I got home so there was no opportunity to reshoot.

My solution was to take the best shot into Photoshop and change the color in the cap back to the correct shade. That edited photo is one of the family favorites.

In your cityscape it may be that the dynamic range between the stop lights and shadows is more than the camera can capture. Reducing the exposure in order to capture the red in the stoplights may result in loss of detail in the shadows which are IMO the more interesting parts of the photo. Were it my shot I think I would just edit the color of the lights.

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I agree with Luke completely. Normally I would expose to preserve highlights, but in this case it would make the entire image too dark. Instead, I would simply change the color of the traffic lights to red. The loss of detail in the lights is insignificant.


Eric Bowles
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I'd approach this just as Luke and Eric said - you can't preserve highlights in light sources. Details there are unimportant, so just shift the color to red. If that doesn't look right, then consider a B&W treatment.

Larry - a Bay Area Nikonian
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>"in raw format the camera white balance is not applied in Lightroom"

Hi Kari

While the real culprit is overexposure, we might as well discuss WB in LR or ACR. While it's true that Adobe products ignore most of the in-camera settings (such as ADL or sharpening), WB is the one parameter that Adobe products do read. If you set WB to "as shot" in LR or ACR, then the value set in (or by) the camera will be honored, although Adobe rendering of the WB setting may not exactly match Nikon's.

Regards, Antero

Thank you again for the helpful comments. I went to a local town and shot traffic lights from -0.7 EV to - 5.0 EV. There's no question that the yellow shifts to a reddish color at the expense of underexposure.

I also looked at some of Ming Thein's street shots at night and his camera also registers red traffic lights as yellow.

I'm kind of surprised. As I understand it, matrix metering is driven by thousands of metered scenes that Nikon feels contribute to proper exposure. I guess there is nothing in that digital information related to red traffic lights that makes them appear in true color without creating severe underexposure. Perhaps I'm misunderstanding the technology.

Nick (Roxbury, Connecticut Nikonian)

Matrix metering looks at points all over the scene to determine the best compromise exposure. This is as opposed to spot or center weighted metering, which only look at one small, contiguous area.

In the end, though, you only have one exposure per shot, not one for dark areas and one for bright lights. That you accomplish with HDR techniques.

Mick
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Nick,
I could be wrong, but I suspect the heart of the problem is that you are dealing with two completely different sources of light. Reflected sunlight is illuminating everything in the picture except, you also have two bright point sources of incandescent, or LED, red light shining directly at the camera. Given the major difference in color temperature of these sources, even with a perfect exposure I don't think you can get the WB of both captured correctly by the camera in the same picture. If you really want the lights to be red, I think you'll have fix it in PP.

To check it out, try shooting one with the WB set to incandescent and see what traffic lights look like. Obviously that will mess everything else up, but you might get red lights.


Dave

I have experienced the same thing with my D800.
Apart from the traffic lights easily becomes over-exposed, backing off the green channel will correct some of the red hue.
So...is there a correlation to the green cast in pics that has been reported?

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Dave,

I believe your observations have merit as have the others. I didn't post the entire image, but there were other red-colored objects in the photo that were properly exposed.

I guess today's technology still hasn't mastered that kind of metering challenge.

Nick (Roxbury, Connecticut Nikonian)

Yes it could induce a slight or pronounced color cast to other parts of the image, depending on the adjustment.

I think you are barking up the wrong tree here with thinking this is WB. It is dynamic range due to the bright red traffic lights. If not totally blown out, you can confirm this by applying negative exposure compensation in your pp software to see if the color improves on this red lights.compensation in you PP software. The re

Mick
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I agree with Mick - I woudl not try to use WB for any correction to red traffic lights. If you look closely at a traffic light (the old ones not the LED ones) you'll see that it does have a bulb that disproportionately lights the center of the light. This makes the center brighter - and causes it to blow out in a photograph. It's an easy fix to change it in post processing.

The green cast that some see is only related to the LCD - not the image. I don't see a green cast, but some prefer a different view in their LCD. Don't change the WB, hue, or color of your images trying to fix the LCD unless you really know what you are doing. Technically, you might have a workflow that ignores those settings for RAW files so the change might not matter, but if you ever shoot JPEGs without resetting the color you will have images that are off rather than just an LCD that is off to your taste.

Eric Bowles
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>Yes it could induce a slight or pronounced color cast to
>other parts of the image, depending on the adjustment.
>
>I think you are barking up the wrong tree here with thinking
>this is WB. It is dynamic range due to the bright red traffic
>lights. If not totally blown out, you can confirm this by
>applying negative exposure compensation in your pp software to
>see if the color improves on this red lights.compensation in
>you PP software. The re
>
>Mick
>http://www.mickklassphoto.com
>or
>Visit
>my nikonians gallery>

I don't believe I've claimed it is a WB issue..??

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I'm afraid it's totally blown out and no amount of exposure compensation, red, yellow, or orange saturation adjustments changes things. I left WB "as shot." The only thing that improved this situation were follow-up photos on another day wherein the exposure compensation was decreased in steps down to -5.0 EV.

I think it has something to do with the frequency of the LED traffic light itself...must be a combination of light/wave lengths that Nikon and others have yet to master with their metering.

Nick (Roxbury, Connecticut Nikonian)

My suggestion about changing the white balance was only to test the theory as to why the lights look yellow instead of red - NOT to fix the problem.

I fully agree with Eric, Mick and others that no change should be made to the white balance of the final image. As I said in my first post, that would only make things worse. The real fix is in post processing - change the color of the lights to red and you're done.

I made my comment about white balance because there are two completely different light sources illuminating the image - the sun and the traffic lights,each with different physical characteristics. So the question of why the color shift from red to yellow occured MIGHT be explained by the technical issue of white balance. Even if the lights were not blown out in the image, there is a chance they still MIGHT look yellow because of this. But regardless, I would not change the white balance of the image to fix it.


Dave

>I agree with Mick - I woudl not try to use WB for any
>correction to red traffic lights. If you look closely at a
>traffic light (the old ones not the LED ones) you'll see that
>it does have a bulb that disproportionately lights the center
>of the light. This makes the center brighter - and causes it
>to blow out in a photograph. It's an easy fix to change it in
>post processing.
>
>The green cast that some see is only related to the LCD - not
>the image. I don't see a green cast, but some prefer a
>different view in their LCD. Don't change the WB, hue, or
>color of your images trying to fix the LCD unless you really
>know what you are doing. Technically, you might have a
>workflow that ignores those settings for RAW files so the
>change might not matter, but if you ever shoot JPEGs without
>resetting the color you will have images that are off rather
>than just an LCD that is off to your taste.
>
>Eric Bowles
>Nikonians Team
>My Gallery
>Workshops
>
>Nikonians membership — my most important photographic
>investment, after the camera

Are you absolutely certain that there is no green cast in the images? If so, can you explain why
I know what I am doing, and I don't shoot jpeg's.

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Would this be a good chance to flex the HDR muscles? Catch everything you like in the scene?

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When you're blowing single color channels and not luminance highlights, you have a color balance issue. While I wouldn't adjust my WB just to correct the traffic light color, in some situations where the predominant color is blown you would want to adjust white balance. For instance, a brightly lit red rose may blow the red channel. By altering color balance away from red, you may get more accurate reds in the image and closer to what you're seeing in reality.


-Alex Rosen
www.flickr.com/photos/klrbee25/

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Alex,

In this case he did not blow out a color channel, he blew out a very bright (relative to the rest of the scene) light source. Further, it wasn't reflective light from a variety of light sources, but rather a direct illumination. When I look at the traffic lights in the original picture, I do see yellow, which leads me to believe that it is not totally blown out.

This is not the predominant color in the scene, nor the predominant light source, just a highlight.

While balance is determined by the color of the light illuminating the scene, not necessarily by the color of what you are shooting. That is why, with an Expodisk or color meter, to take your measurement you aim it at the light source, not at the subject.

Mick
http://www.mickklassphoto.com
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Below are two images: (1) a snippet of most of the RAW image with no adjustment except for a -81 with LR4 highlights slider, and (2) the accompanying histogram of the adjusted image.

Nick (Roxbury, Connecticut Nikonian)

Attachment #1, (jpg file)
Attachment #2, (jpg file)

The red in the distant buildings looks blown too.


-Alex Rosen
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But not the red on the sign on the right, or the taillights on the car. It is the brightness, not the reds causing the problem.

Mick
http://www.mickklassphoto.com
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This is nothing really to do with frequencies of the lights or inadequacies in metering systems. Digital photographs can only capture so much dynamic range in a scene.

So in a scene such as this, with a normally exposed image the bright lights will tend to blow. Normally really it doesn't much matter, except that the light in question looks weird as it should be red, according to our clear expectations of what a traffic light should look like.

As in the attached example you get similar effects with stop lights at the back of cars, though it's perhaps less noticeable.

If you stopped down to preserve the red in the light the shadows throughout the photograph would get very dark and noisy, so IMHO the best thing to do is to ignore it or redden it in PP as several others have suggested.

Shooting at a lower ISO might help a fraction, this was taken at ISO800, and a lower ISO would have improved the dynamic range, and/or enabled better shadow rendition had you underexposed a little vs the exposure indicated by matrix metering.

Cheers

W i l l

Nikonian in Bogor, West Java
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Attachment #1, (jpg file)

If you shot in RAW and you have PS6.
Just simply move the Highlight slider to the left until traffic light turns red. Done.

As mentioned in an earlier post, that did not work. Only thing that worked was to reshoot with exxposure comp sent to about -3 to -5 EV.

Nick (Roxbury, Connecticut Nikonian)

So the image you posted is already been adjusted? Because it does not look like traffic light is several stops overexposed. Why don't you post original RAW?

In the original post of this thread, I indicated that no development adjustments were made. The Raw image is about 45MB...I don't know how to post that.

In reply #23 of this thread, I posted an adjusted image with its histogram.

Nick (Roxbury, Connecticut Nikonian)

As Nick said and illustrated in reply #23 above, he has already tried using the highlight slider (in Lightroom), without success - so it would not seem to offer a solution in this case.

Posting a RAW image is not possible at Nikonians.

Brian
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I don't know about Lightroom but in PS6 I do it all the time and as long as highlight is not completely blown I can pretty much bring back most of it. Also works great on sunset photos.

I see no difference in Highlight adjustment between the first post and post #23. If that is the case red light was completely blown but it is hard to tell from the small picture.
The only thing I would do without sacrificing the rest of the picture shooting 5 stops underexposed is to shoot again using 4 fps.
The red light in some frames would have less intensity, less glow at start and finish. Looks like you caught it at the peak of the cycle.

As far as sharing a RAW file you can sign up with MediaFire for free.
Upload it there and post a link here.

That's really the point. I took the original post to -81 in LR4 for highlights. The histogram no longer registerd highlights on the right vertical axis but the color was still predominantly yellow.

The red light was apparently completely blown. I took other images the next day with exposure compensation adjusted to -3 to -5 EV before the light began to turn red.

Nick (Roxbury, Connecticut Nikonian)

If you move Highlight slider all the way to -100 does the red light become grey?

No, at -100, the traffic light is still yellow.

Nick (Roxbury, Connecticut Nikonian)

I wish you could post the file so I can try to work on it.
Here in LA I shot many traffic lights and always get dark red.