obs

obs

Implementation of AgX for OBS as a script.

This is mainly intended to be applied on live camera feeds as this would not have many benefits applied on desktop capture.

default rendering	with AgX filter

video device is a "standard" Logitech C922 webcam for the above comparison

Features

Colorspaces available as input and output :

open-domain	display-referred	camera vendor
sRGB Linear	sRGB Display (EOTF)	Cinema Gamut (Canon)
BT.2020 Linear	sRGB Display (2.2)¹	F-Gamut FLog (Fujifilm)
DCI-P3 Linear	BT.709 Display (2.4)	F-Gamut FLog2 (Fujifilm)
Passthrough²	DCI-P3 Display (2.6)	N-Gamut (Nikon)
	DCI-P3 D65 Display (2.6)	S-Gamut (Sony)
	DCI-P3 D60 Display (2.6)	S-Gamut2 (Sony)
	Apple Display P3	S-Gamut3 (Sony)
	Adobe RGB 1998 Display	S-Gamut3.Cine (Sony)
	BT.2020 Display (OETF)	V-Gamut (Panasonic)

• ¹ parenthesis for display-referred colorspace indicate transfer-function characteristic. 2.2 being the power function.
• ² Means "no color-transformation applied"

Grading Options :

• Exposure
• Gamma
• Saturation
• Highlight Gain
• Highlight Gain Threshold
• White Balance Temperature
• White Balance Tint
• White Balance Intensity

All gradings options are available a "pre image-formation" (linear open-domain) and "post image-formation" (display-referred closed-domain). Grading in "pre image-formation" is performed in a linear sRGB working space and "post image-formation" is performed in the Output colorspace selected.

Requirements

• This has been developed on OBS 28.1.2 for Windows but should work for lower and upper versions, and other operating systems.

• Nothing more than the content of this directory.

Installation

Instructions are also available as video :

Download this whole GitHub repository.

Put the whole content of the obs/obs-script directory anywhere you want on your system (you DON'T need the doc/ directory).

1. Open OBS
2. In the top menu > Tools > Scripts
3. Click on the + button, and browse to the location of the obs-script/AgX.lua file.

The script is now active. A new filter has been created :

1. Go to your Scene/Source where you want to add the AgX filter and select it (the source)
2. Click on the Filters button that should be a bit above the source.
3. In the Effect Filters section, click the + button and choose AgX

All done ! You can now configure it.

Configuration

Important

Reminder that AgX being a display transform it should be placed at the very end of the image processing chain (= at the bottom in OBS).

The camera/video-source and your lighting setup will affect how much you need to tweak the parameters. There is no setup that work for all cases, but once configured for your camera/usual lighting, you should not need to touch it anymore.

Guidelines

I recommend to :

• Pre-Grading
  • boosting the Grading Exposure by +1.0 stop if you are in a dim environment.
  • boosting Highligh Gain by 2.0 (always better)
  • White Balance: intensity at 1.0 and use tint ~10.0 if your camera tend to have to produce pinkish tones (noticable on skin).

Available Options

Input Colorspace

Pick in which colorspace your source is encoded.

Passthrough means no decoding is applied.

Output Colorspace

Target colorspace encoding. Must correspond to your monitor calibration.

Tip

You can request adding new colorspace by opening an issue on GitHub !

DRT

Pick the DRT to use. Technically here we could include other DRT than AgX. But for now only None and AgX (with 2 variants) are available.

• None will not apply AgX but still allow you to use the grading options.
• AgX w/Outset is AgX but with an additional transform to restore chroma. This can reintroduce shift and skews but might be acceptable.

Pre-Grading/...

Adjust imagery look in a linear space, before AgX is applied.

Grading/Exposure

Exposure in stops. 0.0 = neutral.

Grading/Gamma

Power function. 1.0 = neutral.

Grading/Saturation

Saturation with coefficient based on the working color-space. 1.0 = neutral.

Grading/Highlight Gain

Only boost the brightest part of the image. The range of those brightests part can be adjusted via Highlight Gain Threshold.

0.0 = neutral.

Grading/Highlight Gain Threshold

See above.

Grading/White-Balance

Shift white tones, applied before all operations.

• Temperature: in Kelvin. Lower=warmer, higher=colder.
• Tint: shift the temperature: >0=greener, <0=pinker
• Intensity: global multiplier for the effect. 0=disabled.

The most "neutral values" when Intensity is 1.0 are Temperature=~5600 and Tint=~-15.5 which try to match the Illuminant E (those neutral values are not ideal and perhaps the white-balance implementation could be improved)

Post-Grading/...

Grading modifications applied after AgX on display encoded data. This will introduce skews, clipping and other artefacts.

Not recommended to use or with very small values, but can help achieve a stronger artistic look.

All parameters are described the same as for the Pre-Grading section.

Debug/CAT Method

Chromatic Adaptation Transform method to chose for whitepoint conversion (when there is a whitepoint conversion between input and output colorspace.)

Default is Bradford and doesn't need to be changed.

Developer

Developer documentation can be found in ../.dev/implementations/obs directory.