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296 Chapter 18: Effects and Environments
a reflector is about 4500 cd because the light flux is
concentrated into a narrow angle.
Photometric lights are unaffected by the Physical
Scale value.
This parameter is animatable.
Color correction check box and color swatch—When
the check box is turned on, color correction shifts
all colors so the color displayed in the color swatch
appearsaswhite.Default=off.
Clicking the color swa tch displays a Color Selector
(page 1–161) so you can choose the color to adapt
to.
You can use this control to simulate how the
eye adjusts to lighting. For example, even when
the light in a room has a yellow hue from an
incandescent light bulb, we will continue to
perceiveobjectsthatweknowtobewhite,suchas
printed pages, as white.
Tip: For t he best results, use a very pale color
correctioncolor,suchasapaleblueorpaleyellow.
Desat ur ate Low Levels —When on, renders dimly
litcolorsasifthelightweretoodimfortheeye
to dist inguish b etween colors. When on, renders
even dimly lit colors. Default=off.
Desaturate Low Levels simulates the eye’s response
to dim lig hting. In dim lighting, the eye does not
perceive colors and sees tones of gray instead.
Theeffectofthissettingisnotapparentexcept
at very low light levels, below 5.62 footcandles
(lumens per square foot). When the illuminance
is less than 0.00562 footcandles, the scene is
completely gray.
Note: 1 footcandle (fc) equals 10.76 lux (lumens
per square meter).
Linea r E x posure Control
Rendering menu > Environment > Environment and
Effects dialog > Environment panel > Exposure Control
rollout > Choose Linear Exposure Control from t he list. >
Linear Exposure Contro l rollout
Linear Exposure Control samples the rendered
imageandusestheaveragebrightnessofthescene
to map physical values to RGB va lues. Linear
Exposure Control is best used for scenes with a
fairly low dynamic range.
Note: Linear Exposure Control should not be used
in animations, because ever y frame will have a
different histogram, causing your animation to
flicker.
Impor tant: The mental ray renderer (page 3–78) does not
support the Linear exposure control.
See also
Environment Panel (page 3–272)
Interfa ce
Br ightness—Adjusts the brightness of the
converted colors. Range=0 to 200. Default=50.
This parameter is animatable.
Co ntrast—Adjusts the contrast of the converted
colors. Range=0 to 100. Default=50.
This parameter is animatable.
Exposure Va lue—Adjusts the overall brightness of
therendering.Range=-5.0to5.0.Negativevalues
make the image darker, and positive values make
it brighter. Default=0.0.