On the Gamma And LUT
panel of the Preference Settings dialog, you set options to adjust
and lookup-table (LUT) values for input and output images and for
the monitor display.
If you use the mental
ray renderer, the Gamma & Gain shader provides an alternate
way to adjust gamma on a per-material basis. See
Utility Gamma & Gain
Lookup-table (LUT) Correction
Lookup-table (LUT) correction
provides compatibility with the same feature used in other Autodesk
Media & Entertainment products such as Combustion and the Vfx
suite: Inferno, Flint, Smoke, and so on. This feature allows studios
to implement a consistent way of displaying colors, assuming that
their monitors are calibrated to the same reference. Thus 3D artists
can produce results that are closer to what the compositor expects
by eliminating a variable in the equation: the way colors are displayed
NoteThe lookup table
controls available here do not affect exposure control or lighting
of the scene. While they do affect the colors of the final image, this
is with regard to the display only. By having a reference across
a studio (with calibrated monitors), using standardized lookup tables
minimizes variability in rendered output.
Also, please note that
the LUT system of the systems suite is complex and offers a variety
of controls and flavors of lookup tables. This feature integrates
the View LUTs only, such as that found in Combustion, where only
the displayed images are modified.
Gamma correction compensates
for the differences in color display on different output devices,
so that images look the same when viewed on different monitors,
or are used as bitmaps or in printed matter.
The calculation of “gamma”
is output_intensity = input_intensity(1/gamma).
That is, the result is the original value raised to the power of
the inverse of the gamma value. One result of this calculation is
that a gamma value of 1.0 does not adjust the image at all.
Gamma = 1.0: no correction
I stands for Intensity.
Another result of the
gamma calculation is that black is not affected by the adjustment,
and neither is white (or any fully saturated color). Gamma adjustment
affects only the midtones of an image.
Left: gamma = 1.8
Right: gamma = 2.2,
The horizontal axis
represents input (the original value) and the vertical axis represents
output (the gamma-corrected value).
Computer monitors don’t
display color in a linear way (as in the first illustration). Also,
the brightness of a monitor tends to make an image seem brighter
than its intensity values really specify. Gamma correction fixes this
problem, and can ensure consistency between different applications
or different monitors. When you set gamma, find a value that makes
middle gray on your own monitor match a true middle (50 percent)
Changing gamma value
to match a monitor's middle gray
The standard gamma value
is 2.2. This is the theoretically correct value, making the linear
color space stored in the bitmap and used by the renderer appear
to be linear on screen.
However, because the
response of photographic film isn’t linear either, some users find
that this theoretically correct value looks too bright and washed
out. A common compromise is to render to a gamma of 1.7 or 1.8,
making things look more photographic; that is, as if the image had
been shot on photographic film and then developed.
We recommend that you always turn on
gamma correction when you share bitmaps between different computers, between
different applications on the same computer, or create renderings
to use in printed matter.
If the only other applications
that use your renderings are also Autodesk Media & Entertainment
products, you might want to use LUT correction instead of gamma
Two common mistakes have
to do with gamma correction:
- Not applying gamma correction when it
should be used. This results in renderings or bitmaps that are too
- Inadvertantly applying gamma correction
twice. This results in renderings or bitmaps that are too bright.
See the Procedures section
below for more detailed instructions.
Gamma and LUT Settings
Gamma And LUT correction
settings are saved with the market defaults for the current custom
Custom UI and Defaults Switcher.
If you open or merge a scene whose gamma or LUT settings differ
from the settings active for 3ds Max, you see a dialog that gives
you the choice of using the current settings, or adopting those
of the file you are loading. For example:
To set the gamma for renderings you will
use as bitmaps or in printed matter:
- Choose Customize Preferences.
Turn on Enable Gamma/LUT Correction.
- In the Display group at the left-hand
side of the panel, choose Gamma.
Use the Gamma spinner to adjust the Gamma value until
the gray square in the center of the display shows no contrast with the
Above: A bad gamma
Below: A good gamma
The value you choose
can vary, depending on your system's monitor.
- Once you have a good gamma value, change
Output Gamma in the Bitmap Files group on the right-hand side of
the tab to the same value as Display gamma.
- Click OK.
To set the gamma for incoming bitmaps
generated (or edited) by other applications:
- Find out whether the other application
has its own gamma correction.
If it does, choose Customize Preferences Gamma And LUT. Turn on Enable Gamma/LUT
Correction, and choose an Input Gamma value that matches the applications.
If the file type (for example, Targa) has an
embedded gamma value, you might need to set Input Gamma to the inverse (1/gamma)
of the file’s embedded gamma, to avoid applying gamma correction
If it does not, choose Customize Preferences Gamma And LUT. Turn
on Enable Gamma/LUT Correction, then in the Bitmap Files group,
change the Input Gamma to a suitable value.
Input gamma set to
a value suitable for a different application
It might take some experimentation
to find the gamma value that best adjusts the bitmaps created by
the other application. The bitmap should appear the way it does
in the other application: if it appears too light or too dark in 3ds Max,
try a different Input Gamma value.
ImportantIf you use bitmaps from multiple applications, and
these different applications have different ideal Input Gamma values,
then turn on gamma correction, but leave Input Gamma set to 1.0.
Instead, for each bitmap you read, use the individual Select Bitmap
Image File dialog to set the gamma value appropriate to the program
that created the bitmap.
Example: To use gamma correction with
- In Photoshop, make sure Edit Color Settings is set
to North America General Purpose Defaults, with Working Space RGB set to sRGB IEC61966-2.1.
This is the default color
correction in Photoshop.
- Also in the Photoshop Color Settings
dialog, change Color Management Policies RGB to Convert To Working RGB.
- In Photoshop, click OK and then save
the bitmap file.
- In 3ds Max, choose Customize Preferences Gamma And LUT.
- On the Gamma And LUT tab, turn on Enable
Gamma/LUT Correction. In the Display group, choose Gamma, then set
the gamma value to 2.2.
- In the Materials And Colors group, turn
on both Affect Color Selectors and Affect Material Editor.
- In the Bitmap Files group, set both Input
Gamma and Output Gamma to 2.2.
- Click OK to close the Preferences dialog.
Now when you use a bitmap
saved by Photoshop, the colors in 3ds Max should preserve the
bitmap’s original colors.
To use gamma with video hardware:
Video devices such as
video tape recorders usually have their own hardware gamma-correction
- If your video device has its own hardware
gamma correction, do not turn on gamma correction in 3ds Max.
- If your video device does not perform
gamma correction automatically, follow the preceding steps for setting
Input Gamma and Output Gamma, using values approprate to your video
device. Typically these will be Input Gamma = 0.45 and Output Gamma
Typical input and output
gamma settings for video that has no hardware gamma correction
- Enable Gamma/LUT Correction
Makes available the controls
for adjusting gamma or LUT correction. Turn off to disable gamma/LUT
Display gamma correction
or lookup tables applies to viewports and the
Rendered Frame Window. Use
the controls in this group to load an Autodesk View LUT or adjust gamma
- Autodesk View LUT
Click the Browse button and
then use the Load LUT File dialog to find and open a LUT file. Thereafter
the LUT file name appears in the text field to the right of the button.
Note3ds Max does not support
generation of LUT files, and no LUT files are included with 3ds Max.
To create a LUT file, use a program such as Combustion.
(The default.) Adjusts
the gamma display for 3ds Max. The spinner value increases or
decreases the value (lightness or darkness) of the solid gray center square.
Adjust the value until the center square is as close as possible
in value to the surrounding checkered border. Range = 0.1 to 5.0. Default=2.2.
If you're creating bitmaps
or renderings that will be sent to someone else, set Output Gamma
to match the correct Display Gamma value. This ensures that the
image will look correct at the destination site.
You can also display
these gamma settings from the Gamma button in the File Browser dialog;
for example, when you are rendering a scene to an image file.
Materials and Colors group
By default, the Gamma
setting affects the viewport display and rendered frames, but not
the Color Selector or the Material Editor. These switches can enable
gamma correction for either or both of these dialogs.
- Affect Color Selectors
When on, the Gamma setting
affects the display of colors on the standard 3ds Max Color Selector. This
setting has no effect on the Object Color dialog.
- Affect Material Editor
When on, the Gamma setting
affects the display of colors on the Material Editor dialog.
Bitmap Files group
- Input Gamma
Adjusts bitmaps that
you load (for example, texture maps), provided that the bitmap type
doesn't override the gamma with its own gamma value. Range = 0.1
to 5.0. Default=2.2.
In the case of Targa
files, for example, the file's inherent gamma will override the 3ds Max Input
Gamma. In this case, set Input Gamma to the inverse (1/gamma) of
the incoming gamma correction. This avoids applying gamma correction
twice, which will make the bitmap too bright.
- Output Gamma
The gamma correction applied
to bitmaps that you render. Set this to match the correct Display
Gamma value. Range = 0.1 to 5.0. Default=2.2.