8

HDRI Files 665
Def Ex posure—
When on, the image will load as is
withoutapplyinganychangestothecolors.When
off, you can use the par a meters in the Exposure
group to remap colors. Available only with the
Real Pixels option.
16 bit/cha n Linear (48 bpp)—Compresses the
luminance selections into 16–bit color space, at 48
bitsperpixel.Thisistherecommendedsetting.To
decompress the luminance for use in the scene, set
the RGB Level on the image’s
Output rollout (page
2–1430)
to the same value as the linear w hite value
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 metho d s , 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 t he
specified amount.
L—Locks the preview luminance scale to the white
linear value. When off, you can change the v alue
manually. Default=on.
Mark White clamp—Masks the white-clamped
values in the prev iew window with the color
indicated by the color swatch. Click the color
swatch to change this color.
Mark Black clamp—When Black P oint is on, this
optionmaskstheblack-clampedvaluesinthe
previewwindowwiththecolorindicatedbythe
color swatch. Cl ick the color swatch to change this
color.
HDRI Save Settings dialog
As of version 8, 3ds Max can render and save
images with 32-bit floating-point channels.
Among the useful applications for this type of
imagery are:
• Compositing: using 16–bit images in a
compositing pipeline can quickly become
a problem as colors are m anipulated. For
example, banding may appear.
• HDR images are not bound to a specific
range (e.g., 0-255 or 0-65535); they have a
dynamic range. As such, high-contrast and
physically accurate values can be stored in
32-bit floating-point pixels.
• Because of their large range of values, HDR
images can easily be modified, and effects can
be reapplied long after rendering, without
affecting the quality of the image. For example,
changing the contrast/brig htness/exposure of a
16-bit image could cause banding, which would
require re-rendering the image. However, the
sameoperationonanHDRimageshouldnot
affect its quality.
Clicking Save or Setup in the
Render Output File
dialog (p a ge 3–8)
displays the HDR Save Settings
dialog.
The dialog lets you choose the source of the values
used for output:
•
Use Non-Clamped (R ealPixel) Color
Channel—
Outputs the image by means
of t he u nclamped color chan nel. T his channel
does not contain atmospherics or render
effects.
•
Use St a nda r d R G B Ch an nel —Saves the
standard RGB channel, which contains