Color Accuracy Presentation - Better Light Inc.

60 Pages·2006·2.48 MB·English

Welcome to the Fifth
Almost-Annual Better Light
Owners’ Conference
…it’s gonna be HOT!!
COLOR ACCURACY
more than you ever wanted to know
- including -
how to improve your camera profile
“Color Accuracy”…
¬ How accurately does a device render color?
¬ …compared to what?
¬ …under what conditions?
¬ …using what terminology?
Spectral response method
compares the actual response of a device with its
theoretical response, based on spectral data for the
reference chart being used, and for the device
1
1.00
0..990 dark brown
dark orange
blue
0..880 white
light brown
violet blue
0.7.70 green
gray 1
pale blue
0.6.60 mediu
m red
ccredd red
0.5.50 ccg
odrlivae yg 2greeenn
ccddar kb plurpele
0.4.40 yelow
medium gray
light purple
0
0..330 yelow green
magenta
dark gray
0.20 reference chart spectral data device spectrlighat cylan response data
light orange
0.10 cyan
0.1 black
0.00
0
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Calculated device response to each
reference chart color patch:
1.00
0.90
0.80
0.70
red response
0.60 green response
blue response
0.50 yellow patch
ccd red
0.40 ccd green
ccd blue
0.30 area under each response curve represents
0.20
the relative signal level for that color channel
0.10
0.00
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This method involves many calculations…
…with little surprise
the measured response of a Better Light scanning back
corresponds very closely to its calculated response
1.00
0.90
0.80
0.70 calc R
0.60 meas R
0.50 but how well does the device responsceaelc G
meas G
0.40 calc B
0.30 correspond to a standard response?meas B
0.20
0.10
0.00
white
gray1
gray2
med gray
dark gray
black
blue
green
red
yelow
magenta
cyan
dk orange
violet blue
med red
dk purple
yel green
lt orange
dk brown
lt brown
pale blue
olive green
lt purple
lt cyan
What is a standard response?
¬ Characterizing the “native” response of a device is a
good first step, but a device should also be capable of
rendering colors according to an accepted standard,
to provide a “standard response”
¬ This usually involves three-dimensional calculations to
convert the device response to a standard response
¬ The above is equivalent to converting from the color
space of the device to a standard color space
Color space – the final frontier…
Adobe RGB 1998 color space displayed by ColorThink
Describing color with a 3D space
brightest point = white
neutrals are
at center
increasing brightness,
decreasing saturation
max diameter =
max saturation
hue
increasing brightness,
increasing saturation
darkest point = black