Creating and Exporting LUTs
Within Premiere Pro (Windows)
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Background |
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CineForm RAW editing workflow for
Premiere Pro
CineForm RAW editing workflow for Final Cut Pro
Global controls for embedded
CineForm RAW active metadata for playback/rendering using
SetActiveMetadata
CineForm RAW
technology primer
(The features
described below are in CineForm Build 161 and later....)
3D LUTs (color
Look Up Tables), organized as a 64x64x64 matrix, are supported
as "active metadata" embedded in CineForm RAW files (and soon
CineForm 444 files). The format of the 3D LUTs obeys the
.LOOK structure defined by Iridas. If material is shot
using an SI-2K camera, 3D LUTs can be embedded inside CineForm
RAW files at record time. Such metadata can be modified in
post - for instance, it can be turned ON or OFF for display or
render purposes, or it can be replaced by a different LUT.
If using a different RAW camera such as Red, Dalsa, or Vision
Research, LUTs can be created and applied in post.
So the question
arises - how do you create new LUTs? LUTs can be created
in Iridas Speedgrade OnSet and Speedgrade DI. But in this
Tech Note we also describe how you can create new LUTs by
exporting single (or stacked) color correction effects applied
to clips on the Adobe Premiere Pro (Windows) timeline when using
Prospect 2K/4K. New LUTs created can be stored and later
applied to new clips.
CineForm's use
of 3D LUTs is both cross-applications and cross-platform
compatible. Considering cross-applications, a LUT created
and applied to a clip inside Premiere Pro becomes associated
with that clip in other applications too. If you exit
Premiere Pro and double click on the clip, it will play with the
associated LUT in Windows Media Player (for instance). If
you move the clip and the associated LUT to MacOS, it will
import into Final Cut Pro or play in QT Player with the the
proper color association.
Below we discuss
how to create new LUTs by exporting color correction effects
applied to CineForm RAW clips on the Adobe Premiere Pro
(Windows) timeline.
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Step 1 - Create a New Project |
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Create a new project in Adobe
Premiere using the Prospect 2K or Prospect 4K project preset
that matches the resolution and frame rate of your source
footage. |
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Step 2 - Enable CineForm RAW
Global Controls |
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Import your
source footage and compile it on the timeline. Go to the
CineForm Playback Settings menu and click on the ‘Global
Controls’ button. Inside the CineForm RAW Global controls menu
enable all of the processing selectors as shown below
Click OK to
return to the CineForm RAW File Metadata menu.
A Note
About White Balance: If your source camera was the SI-2K,
you may have set White Balance in the camera at record time. If
so the White Balance settings should appear as below, with some
parameters different than 1.000. If you did not set white
balance, or if you used another Raw camera your white balance
settings are likely set at 1.000 for all three parameters.
If you want
to adjust white balance from within the timeline or preview
windows in Premiere Pro, simply click on the "Pick"
button shown in the File Metadata panel and click the
preferred region of the screen as your white reference.
The Gain parameters shown below will automatically adjust.
Of course you can modify the Temp and Tint controls for fine
tuning.
To
demonstrate the non-destructive nature of adjusting white
balance, if you deselect the White Balance control below, the
original (non-white balance) image will reappear.
Click SAVE to
return to the CineForm Playback Settings Menu. |
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Step 3 - Enable the Bit Depth
Indicator |
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In the CineForm
Playback Settings, enable the option that says ‘Display
filter stack’s bit-depth (8, 16 or 32)'. By selecting
this option, you will now see a small bit-depth indicator in the
lower left hand corner of your Program Monitor (next diagram
down).
This option
is important when generating LUT files with Prospect 2K/4K.
During the LUT creation process you’ll be applying effects and
filters to your clips. Some of Premiere’s native effects are NOT
32-bit. If you apply an 8-bit effect, the bit-depth indicator
will inform you. If that happens, you’ll know that the effect
should probably not be used in creating your LUT. We recommend
using only 32-bit effects and filters!
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Step 4 - Apply Filters/Effects to
Create the "Look" |
For this Tech
Note, we’re going to apply Premiere’s Fast Color Corrector
effect to our clip. Drag the Fast Color Corrector effect onto
your clip in the timeline. Then adjust the color in the Effect
Controls panel. In this example, we’re going to adjust the Input
Levels by bringing the whites way down. Change the White Input
Level from 255.0 to 180.0.
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This adjustment
brightens up the image - perhaps beyond what you would normally
want (highlights are clipped). But we’ll do this anyway for now
as it will help us emphasize a later point.
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Now adjust
the hue a little to give the clip a unique new look. Your
settings don’t need to match the ones in this Tech Note. |
Now we have a
new look that we’re ready to export.
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Step 5 - Export the LUT |
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To export the
timeline color corrections as a new LUT, go to File > Export
> Movie… and click on the ‘Settings’ button.
In the
‘File Type’ drop-down menu, select CineForm Look File
Exporter. The procedure for exporting LUTs works similarly
to exporting a rendered sequence, but in this case a series of
auto-named LUTs will be exported based on the color corrections
applied for the segment of the timeline being exported.
 Click
on the ‘Compile Settings’ button if you want to change
the default export options.
As shown,
white balance and source color matrix are NOT flattened into the
LUT. This means that the LUT only represents:
- color corrections applied
- source curve
- source 3D LUT. If there was a 3D LUT that was already
present in the file then
the new LUT will include the
source LUT also
In most cases
you’ll want to leave these at the defaults.
Click ‘OK’
to exit the Compile Settings menu and click ‘OK’ again to
close the Export Settings window.
Choose a name
for your new look and click ‘Save’.
NOTE: If you have multiple clips on the timeline, each
with their own color correction applied, the CineForm Look
Generator will create multiple look files based on each clip.
Lets say you named the export ‘My New Look’. The look created
from the first clip on the timeline will be called ‘My New
Look’. The second clip will be called ‘My New Look 001’. Each
sequential clip on the timeline will be named with the next
sequential number. |
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Step 6 - Apply the LUT to the
Clip |
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Turn OFF
the Fast Color Corrector in the Effect Controls panel so the
timeline now shows the original (pre color corrected) clip.
In the
CineForm Playback Settings click the ‘File Metadata’
button.
Check the ‘Apply
Look’ box and then choose the new look from the drop-down
menu.
Click ‘Save’
and then click ‘OK’ to return to your timeline. Your new
look is now applied to the clip and can be played in real time. |
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Step 7 - Get Back Your Highlights |
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Remember in Step
4 we brought down our White Input Levels to the point where we
image highlights? Now we’re going to get them back using the
CineForm Color corrector.
First, change
the Program Monitor to display the RGB Parade. It should look
similar to the image below.
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Notice the
clipping at the top of the waveform. We’ve clearly lost detail
in our highlights.
Now, add the
CineForm Color Corrector to the clip and adjust the
Brightness control. Set it to about -35. |
Notice the
clipped image highlights have been recovered. Using the
CineForm Color Corrector, the highlights are retrievable and the
clip will still play in real time.
Note: How
is this? CineForm effects and LUTs use floating-point arithmetic
allowing whites with two stops greater than 1. As long as
the clip has not been rendered - which flattens the previous
clipping into the file - the highlights can be recovered.
Below is our
final clip with the new LUT applied, but with the Brightness
pulled down to recover the blown highlights that we created with
our LUT.
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