Colour correction nightmare

Discussion in 'Digital Darkroom' started by adam_patterson|1, Jun 22, 2009.

  1. i have a series of night shots taken with with canon 5d mk II on AWB which have come out with a hideous yellow colour casting that I cannot seem to correct. I have tried fixing it in raw with temperature, hue etc and in photoshop cs4 with curves (marking white, grey and black points) and manually with colour balance, selective colour etc...
    i am yet to even get close to the original colours and am desperately in need of advice?
  2. What are you editing it in?
  3. Peter -
    Shot in raw with raw processing using bridge, then tried in photoshop cs4
  4. If you shot them under sodium vapor street lights then you will not be able to correct them.
  5. Maybe the colors were that desperate? Especially night colors can be really weird, if you linger on the sidewalks. Sometimes the choice is to accept the freakish colors, or to go black and white. An example would be helpful, of course.
  6. see the shot below - sodium vapor street lights? I have no idea, but it seems I should have, at least if I want to avoid this again...
  7. The problem with sodium vapor lights is that they emit only a narrow spectrum of light. Nothing to balance between, since it's essentiallly monochromatic.
  8. thus is there no way I could have countered this while shooting? - ie. manual white balance?
    thanks for the explanation
  9. In the archives there are references to a physical filter for correcting light under sodium vapor lamps. However, because the light is monochromatic the result will be very, very long exposures. Certainly nothing appropriate for your subject matter.
    Best solution, IMHO: convert the images to B&W
  10. Rob -
    Thanks mate, my final questions, any ideas how Carlos Cazallas got these results;
    perhaps they were not sodium lights?
  11. Maybe mercury-vapor lights or metal halide lamps?
  12. jtk


    Convert RAW to B&W.
  13. Just FWIW, Mercury vapor lamps are a different color, but aren't fundamentally a lot different from sodium vapor.
    Metal halide lamps are a whole different story though -- most of them produce quite a nicely balanced spectrum.
    As far as the Carlos Cazallas pictures go, it looks to me like they vary pretty widely -- some show fairly reasonable color, while others show strong casts. The first shows some of each -- the foreground is fairly pure, but the background has a strong cast. The street lights in his pictures don't look like sodium vapor, but it's almost impossible to say exactly what they really are. In some cases, he may have a combination, such as flash for a balanced foreground along with existing light for the background (again, impossible to say for sure).
    When you shoot by available light, you're pretty much at the mercy of the available light -- if you happen to be under light that has a fairly balanced spectrum, you get a fairly balanced spectrum. If you're under mercury vapor or sodium vapor lights, you don't.
  14. Spearhead

    Spearhead Moderator

    It makes a fine black and white shot, otherwise there's not much other than hand coloring that will fix it.
  15. Jerry,
    My understanding of mercury vapor is that modern bulbs are coated and able to produce better color. (i.e. the light is not monochromatic).
  16. I'll take your word about non-monochromatic MV bulbs -- in the early '80s (or so) you saw a lot of them, but I haven't seen any with the characteristic blue color for a long time. I don't know how much of that is due to changes in the mercury vapor bulbs, and how much is due to just changing to different kinds of bulbs completely though.
  17. Trying to upload a picture to show the problem.
  18. Try this:
    Hit Crtl +1, crtl +2, crtl + 3 to look at the individual color channels. Usually the problem with those streetlights is that they emit no blue light. So it's like you have no blue channel to work with.
    2- In the image I uploaded (previous post) shows my attempt at white balancing it. I don't think white balancing will ever work since the color information simply isn't there. The highlights are yellow and the shadows are blue (may be from the sky?).
    3- I would just throw a tint on it and call it a day.
  19. I quite like the shot. About the color, it's right that there's no blue channel. You can try just working with the R and G channel if you want to. Once you brighten the image (curves or levels) You can also play around with color balance to see what's possible. Here's what I came up with.
  20. I'm curious. Would shooting this under the custom white balance setting work? The setting where you meter against something white under the conditions your shooting in. I've never used a 5D MkII but I know there are Canon's with this setting.
    Or is the spectrum emitted just that narrow that you'd be out of luck regardless of how you metered the scene?
  21. I have not yet encountered this, but it seems the R and G channels are identical, just exposed differently. Apply levels, and drag your highlight to the right edge of the histogram in each channel, then flip back and forth between the channels, they're nearly identical. The B channel is worthless here. No luck in LAB either.
    So i would say, no a custom white balance would not work. the spectrum sucks.
  22. You have almost no variation in hue to work with in correcting this image. Very little that can be done outside of hand coloring or making it BW or a duo or tri tone.
  23. [[Or is the spectrum emitted just that narrow that you'd be out of luck regardless of how you metered the scene?]]
    "Spectrum of a low-pressure sodium lamp. The intense orange band on the left is the atomic sodium D-line emission, comprising about 90% of the visible light emission for this lamp type."
    (emphasis mine)
  24. This is clearly a monochrome image. There is essentially only one color. I like the Sepia version your white balance produces. To me, it looks like reality. Sometimes, I do not understand all that fuzz about white balance. Things look like this at night. A Tungsten lamp looks awful in colors, a bulb looks reddish/yellow, sunset looks red, shadow looks cooler. I try to stick with small adjustments not to destroy my personal feelings of the scene.
  25. I like the image as it is. Print it.
  26. You might try desaturating it by tiny bits, however, to see which degree of desaturation you like the best. Black and white (100% desat) is always good, in my opinion.
    I would consider brightening it ever so slightly.
  27. Here it is with an increase in brightness and a substantial degree of desaturation. A traditional sepia might work better than "sodium line yellow," however.
  28. It occurred to me that you also might want to crop the photo to show the couple more clearly.
  29. I'd agree, nothing can be done in the camera to avoid this type of issue, you just do not have good light to work with. But, can still be fun to work with it.
    An option to just throwing a tone on it, would be to do what the IR guys do and copy the red or green channel to the blue, then manipulate each channel to create false colors. It kind of looks like the link above does some of that. The IR guys are kind of in the same situation, identical channels and a narrow band of light. And, some can make really cool images.
  30. I thought the many, many color controls in ACR 5.4 would allow me to pull something near normal out of the image.
    I was wrong.
    The best I could do was to reduce the strong yellow highlights.
    Split toning also produced some interesting variations.
  31. Maybe using the Canon DPP software would make a difference.

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