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1. Re: Raw Editor Slider Nomenclature
MadManChan2000 Mar 5, 2008 5:57 PM (in response to George Austin)The temperature, tint, and exposure sliders have no direct correspondence to the CIE Lab (L*a*b*) color space.
Temperature and tint determine the white point (neutral values). -
2. Re: Raw Editor Slider Nomenclature
George Austin Mar 5, 2008 9:03 PM (in response to George Austin)The light bulb has not come on. Care to elaborate? -
3. Re: Raw Editor Slider Nomenclature
(Jeff_Schewe) Mar 6, 2008 4:01 AM (in response to George Austin)You need to think in degrees Kelvin where the white balance is in the yellow/blue scale and the tint is in magenta/green. As Eric indicates, this has nothing directly to do with Lab color coordinates but the Kelvin scale...see: http://en.wikipedia.org/wiki/Kelvin -
4. Re: Raw Editor Slider Nomenclature
George Austin Mar 6, 2008 11:37 AM (in response to George Austin)Well, the light is on but the dimmer switch is stuck on low.
The temperature and tint sliders each range from -100 to +100. What units? I'm guessing percentage but, then, percentage of what?
I presume 0 on the temperature slider represents 5500 K. If I set the slider to -50 would that be 50% lower (2750)? If set to +50, 50% higher (7750)? Or does 0 represent the as-is temperature and the slider percentages of it? Or...?
Is it natural or arbitrary to assign yellow/blue to temperature and magenta/green to tint? -
5. Re: Raw Editor Slider Nomenclature
John_Cornicello_Photo Mar 6, 2008 12:25 PM (in response to George Austin)Ah, another light goes on for me! Are you opening JPG and/or TIF files in Camera Raw? When working with raw files the temperature slider should show degrees Kelvin. If you have a zero point, that probably refers to the starting out place in a JPG or TIFF file where you can't really change the color temp the same way you can in a raw file.
Yes, I think it is natural to use yellow/blue for temperature. Think about color correction filters 81a, 82b, etc. They tend to be blue or yellow/coral. Then the tint would be color compensation filters (add 10cc of magenta, etc.). -
6. Re: Raw Editor Slider Nomenclature
JimHess-8IPblY Mar 6, 2008 12:29 PM (in response to George Austin)George,
You must be working on JPEG images in ACR. If you work on raw images they will display the color temperature. For instance, my camera seems to always translate to 4700 after download. And when you click on the pulldown you have different options like daylight, flash, fluorescent, tungsten, etc.. But these options are not available on JPEG images, at least with my camera. -
7. Re: Raw Editor Slider Nomenclature
George Austin Mar 6, 2008 1:01 PM (in response to George Austin)Yes, I am working JPEG files. What are the temperature and tint slider numerical setting meanings in JPEG? -
8. Re: Raw Editor Slider Nomenclature
John_Cornicello_Photo Mar 6, 2008 1:12 PM (in response to George Austin)When working with JPG files negative temperature values add blue to the image. Positive values add yellow.Negative tints add green, positive tints add magenta.
They both use a -100/0/+100 scale. But I don't know if the numbers translate to any specific Kelvin numbers or micro reciprocal degree (Mired) shifts.
If you are trying to neutralize a color cast in a JPG via Camera Raw it might be easier to use the White Balance Tool (eyedropper next to the hand) to click on something that should be a neutral gray in the image. -
9. Re: Raw Editor Slider Nomenclature
JimHess-8IPblY Mar 6, 2008 1:16 PM (in response to George Austin)As I understand it, the JPEG images come up with everything set as shot. If you adjust to the left, the image becomes cooler, adjust to the right, it becomes warmer. I don't think the number actually means anything. It's just a value that ACR can read and copy.
Although we have the capability to edit JPEG images in ACR, that is not what ACR was primarily designed for. Use it, and adapt it to your workflow if you want to, but don't try to correlate those numbers with anything. -
10. Re: Raw Editor Slider Nomenclature
George Austin Mar 6, 2008 2:07 PM (in response to George Austin)"...When working with JPG files negative temperature values add blue to the image. Positive values add yellow. Negative tints add green, positive tints add magenta..."
Just exactly what the -b/+b and -a/+a channels, respectively, do in LAB. -
11. Re: Raw Editor Slider Nomenclature
George Austin Mar 6, 2008 6:16 PM (in response to George Austin)Wait a sec! Strike thw word "exactly". Not at all exactly. Hmmm. -
12. Re: Raw Editor Slider Nomenclature
George Austin Mar 6, 2008 6:56 PM (in response to George Austin)duplicate -
13. Re: Raw Editor Slider Nomenclature
Ramón G Castañeda Mar 6, 2008 8:20 PM (in response to George Austin)Read posts #1 and and #3 again. They are by the guy who writes the code and the guy who literally
b wrote the book
on Adobe Camera Raw respectively. It just doesn't get any better than that. :) -
14. Re: Raw Editor Slider Nomenclature
George Austin Mar 6, 2008 10:53 PM (in response to George Austin)Ramon,
The "guy who writes the code" was unknown to me but I have long been aware of the other guy's awesome credentials. Your advice is well taken.
George -
15. Re: Raw Editor Slider Nomenclature
George Austin Mar 7, 2008 11:52 AM (in response to George Austin)Eric Chan's web site: http://people.csail.mit.edu/ericchan/
Eric is clearly a rising young star. His web site is full of expertise made comprehensible by meticulous organization of material. See especially his stuff on printers and profiling. Best I have seen. Thank you, Eric.



