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HDRI Files 615
clamped to black. When this option is turned off,
thelowestpossiblevalueisusedastheBlackPoint.
Measured M in/Max—Displays the actual minimum
and maximum luminance values in the image,
expressed as both the logarithmic and linear
values. Using these values for the Black Point
and White Point will result in the image’s full
luminance range being used. H owever, the
histogram might show that the majority of the
luminance levels fall into a much smaller range.
White Point—Sets the luminance va lue that you
would like to be considered the brightest color,
or “white”, either as a logarithm (Log) or linear
value (Linear). All luminance values in the image
thatareabovethisvaluewillbeclampedtowhite.
White pixel values inside HDR files can b e much
larger than a Linear value of 1.
The image’s extended luminance range is used
only when the White Point’s Linear value is set
above 1.0. In other words, sett ing White Point at or
below a Linear value of 1 .0 will not use any of the
HDR image’s special luminance propert ies, and
will give results similar to other bitmap formats
such as TIF and JPG.
Log—Sets the Black Point or White Point as a
logarithmic value ranging f rom –128 to 127.
Changing this value changes the Linear par ameter
to the corresponding value.
Linear—Sets the Black Point or White Point as
alinearvaluerangingfrom0toover1trillion.
Changing this value cha nges the Log pa rameter to
the corresponding value.
Preview window—Displays the selected HDR
image.
Internal Storage group
Rea l Pi xels (3 2 bpp)—Compresses the luminance
selections int o a color space with 32 bits per pixel.
PremultipliedAlphaandMotionBlurdonotwork
w ith this option.
Def Ex posure—When on, the image will load as is
withoutapplyinganychangestothecolors.When
off, you can use the parameters in the Exposure
group to remap colors. Available only with the
Real Pixels option.
16 bit/chan Linear (48 bpp)—Compresses the
luminance selections into 16–bit color space, at 48
bits per pixel. This is the recommended setting. To
decompress the luminance for u se in the scene, set
the RGB Level on the image’s Output rollout (page
2–1621) tothesamevalueasthelinearwhitevalue
on this dialog.
8 bit/chan Linear (24 bpp)—Compresses the
luminance selections into 8–bit color space, at 24
bits per pixel. This compression method uses less
memory than other methods, but it is generally
not adequate to display the range of luminance in
a HDR image, and can result in banding or other
artifacts.
Display scaled colors by —When on, this value
scales the preview image’s luminance value by the
specified amount.
L—Locks the preview luminance scale to the white
linear value. When off, you can change the value
manually . Default=on.
Mark White clamp—Masks the white-clamped
values in the preview window with the color
indicated by the color swatch. Click the color
swatch to change this color.
Mark B lack clamp—When Black Point is on, this
optionmaskstheblack-clampedvaluesinthe
previewwindowwiththecolorindicatedbythe
color swatch. Click the color swatch to change this
color.
HDRI Save Settings dialog
3ds Max can render and save images w ith 32-bit
floating-point channels. Among the useful
applications for this type of imagery are: