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614 Chapter 20: Managing Scenes and Projects
the majority of the g raph, and the prev iew
image is satisfactory.
Tip: FortheInternalStorageoption,usethe
default choice of 16 bit/chan Linear (48bpp)
unless you have a specific reason for doing
otherwise.
6. When you have finished adjusting values, note
the Linear White Point va lue, and click OK to
accept the settings.
7. In the Material Editor, expand the Output
rollout. Set the RGB Level to the same value
astheLinearWhitePointvalueontheHDRI
Load Settings dialog.
The result is a map with a wide range of deep
blacks and very white hig h li g hts. If such an
image is used as both a background in the
rendering and a reflection map on an object,
the object will appear to b e extremely shiny and
reflective.
Inter face
HDR Load S ettin g s dialo g
WhenyouopenaHDRfileasabitmap,theHDR
Load Settings dialog appears. This dialog allows
you to specify the luminance ra nge to use from the
image, an d the method for storing the data.
Histogra m—This gr aph shows the image’s
luminance values in a logarithmic scale. The red
lines indicate the cur rent Black Point and White
Point values.
Thegraphisvisibleonlyforluminancelevels
with substantial representation in the image. In
other words, if a luminance level only applies
to one or two pixels in the image, there will be
no corresponding graph line on the histogram.
Compare with Measured Min/Max, which gives
theentirerangeofluminancelevelsintheimage.
Ingeneral,theresultingimagewillhavethemost
dramatic effect when the histogram is used to set
theBlackPointandWhitePointrangevalues,
rather than using the f ull range expressed by
Measured Min/Max.
Exposure group
Black Point—When this option is turned on, you
cansettheluminancevaluethatyouwouldlike
to be treated as the darkest color, or “black”. The
value can be set as a logar ithm (Log) or as a linear
value (Linear). All values below this value wil l be