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12/29/2005 12:00:53 PM · #1 |
My *new* 5d has the RGB histogram available. Why would I use it? How do I use the information to make adjustments to get the best shot?
I have always used the lightness histogram to make sure my exposure is ok, but I'm in the dark with the RGB.
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12/29/2005 12:05:55 PM · #2 |
| all you can use that graph for is to show your sell how the saturation of the colors is playing out in the photo. |
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12/29/2005 12:17:26 PM · #3 |
| Different channels will blow out at different points. You can use the RGB histogram to ensure none of the channels have blown out areas. |
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12/29/2005 12:57:20 PM · #4 |
Originally posted by radionin:
all you can use that graph for is to show your sell how the saturation of the colors is playing out in the photo. |
Heavens, no...
The luminosity histogram (the one shown on most cams) is a combination of all three channels. If one channel is saturated while the others are not, the luminosity histogram likely will not show any sign of clipping. This happens VERY often with subjects that are saturated, primary colors.
With the RGB histogram, you see the histogram for each individual color channel, and so you can clearly see if one is clipped. It's far superior to a luminosity histogram, and once you learn to interpret the results, you'll wonder how you ever lived without it.
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12/29/2005 01:12:09 PM · #5 |
Originally posted by kirbic:
Originally posted by radionin:
all you can use that graph for is to show your sell how the saturation of the colors is playing out in the photo. |
Heavens, no...
The luminosity histogram (the one shown on most cams) is a combination of all three channels. If one channel is saturated while the others are not, the luminosity histogram likely will not show any sign of clipping. This happens VERY often with subjects that are saturated, primary colors.
With the RGB histogram, you see the histogram for each individual color channel, and so you can clearly see if one is clipped. It's far superior to a luminosity histogram, and once you learn to interpret the results, you'll wonder how you ever lived without it. |
Great - so how do you interpret the results? Give me a scenario and the adjustments you'd make to fix the blown out color...
Thanks,
E |
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12/29/2005 01:13:19 PM · #6 |
Maybe I'm talking about something different
//en.wikipedia.org/wiki/Image:Vectorscope_graticule.png
I guess I was talking about a vectorscope I know which one you are now talking about I personal never use it that often. I realy just work with my Lum histgraph and the vectorscope. I wish I could see a lum histograph when I'm shooting I would expose with it. anyways |
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12/29/2005 02:32:50 PM · #7 |
Originally posted by eslaydog:
Great - so how do you interpret the results? Give me a scenario and the adjustments you'd make to fix the blown out color...
Thanks,
E |
Let's say you're taking a pick of a red rose...
Scenario 1:
You snap the shot, and look at a luminosity histogram, it all falls within the bounds of the horizontal scale and the pic looks fine as you "chimp" it on the LCD. Later, at home, you bring it up on the 'pooter, and discover that the red channel is blown out over much of the flower, and think "WTF?? The histogram didn't show any problems?"
Scenario 2:
You snap the shot, review the RGB histogram, and see that although the Green and Blue curves are within the window, the red curve is bunched up against the right end, with a giant spike at far right. You think "OOPS, blew the red channel," reduce exposure by a stop, and reshoot. Later, at home, you bring it up on the 'pooter and are awed by your talent...;-)
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12/29/2005 02:48:20 PM · #8 |
Originally posted by kirbic:
Originally posted by eslaydog:
Great - so how do you interpret the results? Give me a scenario and the adjustments you'd make to fix the blown out color...
Thanks,
E |
Let's say you're taking a pick of a red rose...
Scenario 1:
You snap the shot, and look at a luminosity histogram, it all falls within the bounds of the horizontal scale and the pic looks fine as you "chimp" it on the LCD. Later, at home, you bring it up on the 'pooter, and discover that the red channel is blown out over much of the flower, and think "WTF?? The histogram didn't show any problems?"
Scenario 2:
You snap the shot, review the RGB histogram, and see that although the Green and Blue curves are within the window, the red curve is bunched up against the right end, with a giant spike at far right. You think "OOPS, blew the red channel," reduce exposure by a stop, and reshoot. Later, at home, you bring it up on the 'pooter and are awed by your talent...;-) |
This is exactly what happened to me this last spring shooting the tulip fields. The reds gave me hell. Another point for moving to the D-200 is see. |
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01/01/2006 01:30:47 AM · #9 |
This is really good info. I guess I'll try the RGB histogram vs the luminous histogram from now on.
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01/01/2006 04:01:23 AM · #10 |
there is alot of info on the net about this. Search it, read it, and learn it. Part of having the camera is knowing how to use it. Learning how to use that RGB histogram will come in use. Take the time.
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02/20/2006 08:49:22 PM · #11 |
I was viewing RGB histogram being explained by Jack Rezniki on Canon's Digital Lerning Center here.
//www.photoworkshop.com/canon/index.html
And he states that if one channel is clipped, then you can turn that channel down in the WB adjustment. If this is the case, can't you do that in PP if you shoot RAW? I was reading RSP's guide and they recommend keeping the camera in AWB and adjusting the WB in PP, since this is more accurate than in camera.
Any thought?
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02/20/2006 09:08:30 PM · #12 |
Originally posted by yido:
I was viewing RGB histogram being explained by Jack Rezniki on Canon's Digital Lerning Center here.
//www.photoworkshop.com/canon/index.html
And he states that if one channel is clipped, then you can turn that channel down in the WB adjustment. If this is the case, can't you do that in PP if you shoot RAW? I was reading RSP's guide and they recommend keeping the camera in AWB and adjusting the WB in PP, since this is more accurate than in camera.
Any thought? |
This is actually an interesting area; the histogram shown on the camera's screen during preview is based on a JPEG conversion using the current camera settings. That means that any WB settings, as well as contrast and saturation settings, WILL affect the histogram behavior, even if you're shooting RAW... it does not affect how the RAW data is recorded, however. Only Aperture, shutter speed, and ISO affect that. Ideally, you'd want the histogram to show you as close to what the RAW data really is as possible. That implies that when shooting RAW, it's best to use a less contrasty (more linear) tone curve and a low saturation setting. For cameras that use "Picture Styles", like both the 5D and 1DmkIIn, that means either the "Faithful" or Neutral" settings. You still have some "headroom" above the clip point shown, but the difference is less dramatic than with more punchy styles. When using Canon's DPP as a converter, any of the available Picture Styles can be alied post-hoc. I prefer starting with a very neutral image, and changing the saturation, contrast & WB as I see fit. Speaking of WB, it's still valuable to set this as accurately as possible, again to get the histogram to reflect reality as closely as you can. It also means less farting around later trying to achieve the correct balance.
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02/20/2006 09:52:10 PM · #13 |
I guess there is always more than one way to skin a cat. I was thinking now that I just use the luminosity histogram and in RAWShooters Premium, adjust tone/hue/colors if one of the channels is clipped. However, I think I'm gonna keep the RGB histogram for now. I'm kinda used to it, if one channel is clipped, then I guess you still can turn down the EV and recover the rest in RAW PP.
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