TonyBeach
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 p.5 #4 · New article - Why shoot RAW - The real answer | |
TonyBeach wrote:
Do some testing (as I've done) and you may see what is going on. Minimizing changes to WB from a neutral setting minimizes issues that do crop up when making changes to WB settings in some RAW converters. Here's a test for you, shoot a CC24 colorchecker at 10000K, 2500K and using uni-WB under sunlight and incandescent lighting, and shoot it so that the 10000K blows a channel; then see if you can restore that blown channel in the 10000K file with NX. Oh right, you can't do that because you don't use NX, but you seem to think you are qualified to pontificate on how every RAW converter interprets WB....Show more →
mawz wrote:
But you're assuming here that I'm going to blow the channel when not using Uni-WB. If I'm using a meter and not the histogram to check exposure, I'm not going to blow that channel in the first place. So ni-WB doesn't save anything.
No, I'm assuming that you want to utilize ETTR, and understand that just because a channel is blown by the WB setting, it isn't actually blown (if you are shooting RAW and not JPEG, which was the original point of this thread).
mawz wrote:
Note it's sort of hard for me to do any conversions in NX these days, I don't shoot Nikon anymore. But I am familiar with NX, given that it was my converter of choice for the D300 and I've done a LOT of conversions in it. I'm also aware that it does tend to handle the preset WB somewhat problematically.
Then you agree that there is a problem that occurs with some RAW converters.
mawz wrote:
Of course I could just load that 10000k file into CaptureOne and rescue the channel just fine that way. No Uni-WB needed.
As much as I like Capture One, sometimes I find myself using ACR or NX. Nonetheless, the more important issue for me is actually being able to see how well exposed my shot is, something that is easier and quicker to do with uni-WB than with any other method (and you've not actually offered any here).
mawz wrote:
You're generalizing one specific implementation to a general superiority of Uni-WB. Now you MIGHT have a point if you specifically state that if you use a supported Nikon body and CaptureNX, then UniWB has some value. But this is the first time you've ever specified a RAW converter. Note my point has ALWAYS been that Uni-WB's value is entirely implementation-specific.
Well, I pointed out in my first reply to you on this that, "RAW converters can do funny things when applying WB gain." I didn't say all RAW converters, and I didn't say it always happens (it never happens with Capture One for instance). That said though, the issue can subtly degrade image quality under some circumstances, and downright ruin it as far as using a preferred RAW converter is concerned in some circumstances.
mawz wrote:
Using a CC30M filter to tame the green channel will have an actual effect in the RAW converter, but at the cost of causing WB problems since you are mucking with the Bayer demosaicing algorithm's basic assumptions. The green channel is stronger for a reason, because the human eye is far more sensitive to green. It's not a very good idea to use a CC30M if you want anything resembling accurate colour.
TonyBeach wrote:
Obviously you haven't done it; because if you had, you would know better (as I do).
mawz wrote:
And you're assuming you know better when your solution breaks both the colour balance assumptions of the RAW converter and of the base colour interpolation algorithm. What you're doing is breaking the green channel in order to rescue highlights in the red and blue channels. It might work in some cases, but it will definitely cause problems in others.
Here's a hint, if taming the green channel didn't have significant downsides, we wouldn't be seeing the current bayer mosaic pattern (or Sony's 2-green variation).
You are clearly confused about what happens when you use a CC filter. There are still two green photosites for each red and each blue photosite; the difference in sensitivity is because less light arrives at each red and blue photosite because those photosites require more filtration than the green photosites require. The only thing that changes when the green light is reduced with a color correction filter is that less WB gain is required to attain a balanced color. In effect, applying a 25% gain to the blue channel and a 40% gain to the red channel (those are typical gains applied under daylight conditions) is the same as boosting the ISO in those channels.
If color correction filters were such a bad idea, than Iliah Borg would not be using them. Iliah is a color guru who uses many systems and writes code for a couple of different RAW converters. I'm sure Iliah agrees with what Joakim (aka, theSuede) wrote above.
If uni-WB was deleterious to demosiacing performed by RAW converters, then Thom Hogan wouldn't use uni-WB, but Thom Hogan does use uni-WB, as does Iliah Borg.
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