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Blown Out Yellow Channel

MatrixphotoMatrixphoto Member
edited August 2011 in general photography
Hi Neil
I have a question about blown out Channels.
In these Example the first one the Out of Gamut warning is off , the second its On.
Everything in the File looks OK but Adobe Raw is telling me that the yellow channel is blown.
Is it really Blown , Because I can still see detail in the fabric.

image
image

1 Is it possible to Correct for this in Camera if so How,

2 How Critical is the Adobe Raw Out of Gamut warning , reason I ask when I turn it off I can still see detail in the area so Im a little stumped

Lou

Comments

  • AllenAllen Member
    edited August 2011
    Hi Lou. The reason the yellow (red and green) channel has blown out and not the white (red, blue and green) is probably due to material used. In my (limited) experience, synthetic fabrics such as nylon seem to be more reflective than natural fabrics like cotton. I take loads of photos of my granddaughters and their pink clothing is my nemesis.

    Anyway, the in-camera solution is checking your histogram and blinkies in the relevant areas of the photo.

    http://neilvn.com/tangents/flash-photography-techniques/7-metering-techniques/

    The "Out Of Gamut" warning is a bit over my head, so I'll leave that to someone else, but it is dealt with in the book "Real World Camera Raw" by Jeff Schewe & (the late) Bruce Fraser, recommended elsewhere on the forum/blog.

    http://www.amazon.com/Real-World-Camera-Adobe-Photoshop/dp/0321580133/ref=sr_1_4?ie=UTF8&qid=1312960919&sr=8-4

    This a link to the PSCS4/ACR 5 version. There is an updated version for PSCS5/ACR6.

    To correct this photo which appears a little over exposed, just drag the exposure slider to the left and, if necessary, drag the recovery slider to the right.

    Edit: I just opened your photo in ACR and the RGB values show that the whites are a bit too yellow (low on blue). Most of the over exposure goes away by using the white balance tool on something that's supposed to be white.
  • Its not an "out of gamut" warning; the red overlay is the Highlight Clipping indicator.
  • Neil vNNeil vN Administrator
    I'd go with what Allen said.
    But in this case, I wouldn't worry too much about it ... unlike if you were a commercial photographer who'd have to meticulously capture the exact shade of yellow.
  • I'd like to have another go at this one... Although Adobe's name for this is "Highlight Clipping Warning", when the exposure is correct it will indicate the over saturation of one colour relative to the colour space being used.

    If you see it as an over saturation of the yellow channel, then reduce it - in this case correcting the white balance does the job.

    If you see it as an "out of gamut" issue - in this case the yellows and oranges are outside the sRGB gamut - then change the colour space to Adobe or ProPhoto RGB. This will get rid of the clipping warning but may also have a knock-on effect.

    An in-camera solution would be a custom / preset manual white balance, but as you shoot in RAW anyway, there's little to gain. And as wedding photographer you probably have other things to do.

    Just one question, Lou. Where did you get the phrase "out of gamut warning"?
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