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[OM] Re: olympus Digest V1 #128

Subject: [OM] Re: olympus Digest V1 #128
From: Stephen Scharf <scharfsj@xxxxxxxxxxxxx>
Date: Thu, 3 Jun 2004 22:54:10 -0700
>Yes, sometimes color is subjective.

Well, color may not be, but our preferences may be. OTOH, exactly 
defining what color is is quite complex, which is why there are color 
scientist who spend their time trying to figure how we see and should 
work with color. Thank goodness for the CIE...

><SNIP>
>Before using PhaseOne I use custom white balance whenever I need "accurate"
>color, after that it is not necessary anymore. It is not convenient to lock
>white balance for out door, color temp could change in seconds.

That's what so nice about shooting RAW and what is so nice about 
digital. That RAW file is like the latent image on a piece of film; 
you can process it whatever way you like, and if you want to, you can 
always go back to it an re-process it AGAIN. OTOH, once the latent 
image on a piece of exposed film  is processed, you can never go back 
and re-process it. LIke you, I like the Capture One RAW workflow 
software very much. I much prefer it to Adobe RAW or camera's mfr's 
convertors.

>
>Beside auto color balance problem, there is something that many people may
>not notice, even I don't have good monitor like you I notice it the first
>time when I saw the picture came out from 10D. The problem was the contrast
>linearlity, the shadow area drop very fast and the area supposted to look
>dark grey becomes black. I confirm the problem is not due to my viewing
>system by changed to PhaseOne, the "film like" setting in PhaseOne totally
>correct this and this is the default setting.

I guess if this were correctable by using C1, then the data was 
actually there and being recorded by the camera; what you're saying 
if I take it correctly is that you feel the JPEG conversion was 
dropping shadow detail to black too quickly?

><SNIP>
>  >
>>  Bear in mind that I am viewing these images on a La Cie Electron Blue
>>  IV Color Reference CRT monitor calibrated with a Gretag-Macbeth
>>  Eye-One Display to a color temperature of D65 and a monitor gamma of
>>  2.2. Your mileage may vary, especially if your monitor is set to a
>>  color temperature notably higher.
>  >
>
>Sorry, I can't agree with your color "correction" it doesn't match with what
>I remember. My monitor is set to 5000K, it is a non professional Sony but
>I'm pretty sure it is accurate enough, as my 4000ED-Slide-5000K light box
>confirmed it quite well, also my Polaroid film recorder output also match
>very well with my screen.
>
>C.H.Ling

The correction was done simply by evaluating the R/G/B numbers with 
the sampler tool and correcting with Curves what is obviously  a 
color cast, according what to the numbers say. A levels examination 
showed me where the black and white points were, and I adjusted the 
levels black and white input sliders very slightly to match that 
according to the photo histogram. For the curves adjustment, I used 
16 as the black point and 245 as the white point, and 128 as the 
midtone point. I applied the color correction to each color channel 
independantly.

But these details are really besides the point- the point was to show 
by example that all image capture devices have inaccuracies in their 
recording of color, whether it's an E-1 or a 10D. I just didn't agree 
that one could take the un-corrected image out of one camera and 
another and say that the color from one is good and the color from 
another is bad, when they both are inaccurate; they are just 
inaccurate in different ways.

As for your monitor, you can set it to whatever you like, however, 
most color management professionals recommend D65 (6500K) for 
photography work; especially if the images are veiwed via computer 
monitor or printed via photo (RGB-emulting) printers, and viewing of 
the print at 5000K in a controlled lighting booth or daylight. 5000K 
is usually regarded as too yellow for accurate color output for these 
applications, and really intended for prepress color management types 
who go to CMYK press using paper stocks that have a rather yellowish 
base, as is frequently the case in the U.S.
-Stephen.


>


-- 


2001 CBR600F4i - Fantastic!

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