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Old February 26th 14, 06:07 AM posted to sci.engr.color,sci.image.processing,rec.photo.darkroom,rec.photo.digital,comp.soft-sys.matlab
Dale[_4_]
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Posts: 131
Default hybrid system the hard way? including film modeling

both empirical (easy way) and mechanistic (hard way) are supported
mathematically by the ICC, but you could do your own system
http:/www.color.org

empirical characterization entails printing an equipment code value
target to the "calibrated" equipment and relating it mathematically as a
profile to the color of the profile connection space, usually cubic, a
three dimensional profile for 3 colorant mediums, I know there are at
least or there once was 4 colorant mediums from Fuji, I'll allow you to
derive this from my post yourself, it is not hard if you know it

even B&W colorants like silver halides have a hue that must be either
maintained or translated in the ICC profile like a three colorant
system, the eye is a three colorant system, I will allow you to derive
B&W yourself, it is not hard if you know it

with the advent of RIMM, ERIMM, and ROMM in ICC you can use digital
manipulation for hybrid systems (you can search for these on the ICC
site and they are from ProPhoto RGB according to wikipedia)

so why would you want to do it the hard way, mechanistically?

1) want to retain analog manipulation methods
2) want to have analog manipulation algorithms within digital
3) want to an analog capture of scene colorimetry
4) multi-stage analog/hybrid systems do not calibrate
(steady-state calibration is a prerequisite for profile characterization)
5) want to design new analog equipment or manipulation
6) want to design new sensitized media for a hybrid system
( a film program was around 5 million at Kodak 17 years ago)
7) want to design a better analog RIMM, ERIMM or ROMM

so how to do it the hard way?

first, you will need a lot of information, the preferred way of getting
this method is from analog media, equipment and software companies, as
opposed to the investment yourself, some analog technology really
requires single layer coatings to resolve crosstalk from spectral
sensitivity and chemical processing, chemical processing can be just the
way it is, process variability across or inside labs, or by design with
things like DIR or DIAR couplers intended to reduce or optimize chemical
crosstalk
http://en.wikipedia.org/wiki/Color_motion_picture_film

Kodak has licensed some hybrid or analog technology to IMAX, the analog
industry may be willing to deal at this point, additionally some analog
and hybrid information may be patented, when I was at Kodak R&D many
things were not patented due to other nations not respecting
intellectual property, PhotoCD was patented as a last ditch effort to
leverage capture film into digital systems

so what type of information will you need?

spectral sensitivity of capture mediums
(for some systems digital capture sensitivity needs resolved to sensor
and filtration)
spectrophotometry of print (subtractive) output mediums
(spectral data might have to be resolved to light source and filtration)
spectroradiometry of display (additive) output mediums
spectroradiometry of analog and hybrid printers
(for some systems such radiometry of equipment needs resolved to light
source and filtration)
chemical colorant response to light of medium (DlogE)
interimage, overall crosstalk of medium
single layer coatings of mediums to resolve chemical versus sensitivity
crosstalk

what are the use cases?
1) captures (digital, hybrid or analog)(scene or like printing density)
2) manipulations (digital, hybrid or analog)
3) outputs (digital, hybrid or analog)

spectral information is a one dimensional look-up table without crosstalk
crosstalks are at least a linear matrix
DlogE is best represented with a rational quadratic, higher math effects
the central linearity, complete linearity effects toe and shoulder,
highlight and shadow detail where dynamic range is low, this is still a
one dimensional look-up table
digital contrast is linear, gamma
hybrid input/output contrast is calibrated for gamma in most cases
multi-stage systems typically use some standard assumptions, mostly what
equipment/software/measurement the systems engineer is working with

any mathematician can take it from here to get all use cases

if you want me to do a use case, just reply, I have a lot of time on my
hands

by the way, there is a book about "making" Kodak film, but not
"designing" it, maybe the author might want to add a understandable
compilation of this to his book
http://www.makingkodakfilm.com/

--
Dale