[libcamera-devel] [PATCH] libcamera: controls: Add controls for AEC/AGC flicker avoidance

[Naushir Patuck]

Hi David,

Thanks for this work!

On Wed, 25 Jan 2023 at 13:20, David Plowman via libcamera-devel <
libcamera-devel at lists.libcamera.org> wrote:

> Flicker is the term used to describe brightness banding or oscillation
> of images caused typically by artificial lighting driven by a 50 or
> 60Hz mains supply. We add two controls intended to be used by AEC/AGC
> algorithms:
>
> AeFlickerMode to determine whether flicker avoidance is active or not.
>
> AeFlickerPeriod to specify a custom flicker period when the period is
> other than 50 or 60Hz.
>
> Signed-off-by: David Plowman <david.plowman at raspberrypi.com>
>

Reviewed-by: Naushir Patuck <naush at raspberrypi.com>



> ---
>  src/libcamera/control_ids.yaml | 52 ++++++++++++++++++++++++++++++++++
>  1 file changed, 52 insertions(+)
>
> diff --git a/src/libcamera/control_ids.yaml
> b/src/libcamera/control_ids.yaml
> index adea5f90..5e5428ea 100644
> --- a/src/libcamera/control_ids.yaml
> +++ b/src/libcamera/control_ids.yaml
> @@ -14,6 +14,58 @@ controls:
>
>          \sa ExposureTime AnalogueGain
>
> +  - AeFlickerMode:
> +      type: int32_t
> +      description: |
> +        Set the flicker mode, which determines whether, and how, the
> AGC/AEC
> +        algorithm attempts to hide flicker effects caused by the duty
> cycle of
> +        artificial lighting.
> +
> +        Although implementation dependent, many algorithms for "flicker
> +        avoidance" work by restricting the exposure time to integer
> multiples
> +        of this cycle period, wherever possible.
> +
> +        Implementations may not support all of the flicker modes listed
> below.
> +
> +      enum:
> +        - name: FlickerOff
> +          value: 0
> +          description: No flicker avoidance is performed.
> +        - name: Flicker50Hz
> +          value: 1
> +          description: 50Hz flicker avoidance.
> +            Suppress flicker effects caused by lighting runing with a
> +            100Hz period (such as produced by 50Hz mains electricity).
> +        - name: Flicker60Hz
> +          value: 2
> +          description: 60Hz flicker avoidance.
> +            Suppress flicker effects caused by lighting running with a
> +            120Hz period (such as produced by 60Hz mains electricity).
> +        - name: FlickerCustom
> +          value: 3
> +          description: Custom flicker avoidance.
> +            Suppress flicker effects caused by lighting running with a
> +            period specified by AeFlickerPeriod.
> +
> +            \sa AeFlickerPeriod
> +        - name: FlickerAuto
> +          value: 4
> +          description: Automatic flicker period detection and avoidance.
> +            The system will automatically determine the most likely value
> +            of the flicker period, and avoid flicker of this frequency.
> +
> +  - AeFlickerPeriod:
> +      type: int32_t
> +      description: Custom flicker period in microseconds.
> +        This value is taken as the current flicker period to avoid. It
> +        is used when the AeFlickerMode is set to FlickerCustom.
> +
> +        For example, to avoid 50Hz mains flicker, you could set the period
> +        to 10000, corresponding to 10ms (twice the mains frequency), and
> +        AeFlickerMode to FlickerCustom.
> +
> +        \sa AeFlickerMode
> +
>    - AeLocked:
>        type: bool
>        description: |
> --
> 2.30.2
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.libcamera.org/pipermail/libcamera-devel/attachments/20230313/e09f55e6/attachment.htm>