[libcamera-devel] [PATCH 1/1] libcamera: controls: Add a control for IQ stability

[Naushir Patuck]

Hi David,

Thank you for this work.

On Tue, 12 Sept 2023 at 15:23, David Plowman via libcamera-devel
<libcamera-devel at lists.libcamera.org> wrote:
>
> The IqUnstable metadata can be used by IPAs to indicate to an
> application that they have not settled sufficiently to produce
> reliable image quality. Applications would be advised to avoid using
> frames flagged in this way.
>
> One example would be when the camera starts, when the AEC/AGC might
> oscillate for a few frames.
>
> Signed-off-by: David Plowman <david.plowman at raspberrypi.com>

I do like this term better than the more generic startup frames we used before.
FYI, I have implemented this control in the RPi pipeline handler that
folks can peek at here:
https://github.com/naushir/libcamera/tree/iq_stability

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

> ---
>  src/libcamera/control_ids.yaml | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
>
> diff --git a/src/libcamera/control_ids.yaml b/src/libcamera/control_ids.yaml
> index f2e542f4..b96e1272 100644
> --- a/src/libcamera/control_ids.yaml
> +++ b/src/libcamera/control_ids.yaml
> @@ -774,6 +774,26 @@ controls:
>              Continuous AF is paused. No further state changes or lens movements
>              will occur until the AfPauseResume control is sent.
>
> +  - IqUnstable:
> +      type: bool
> +      description: |
> +        The value true indicates that the camera algorithms have not settled
> +        sufficiently to generate images of reliable quality. The application
> +        receiving this frame is advised to drop it and wait for a frame where
> +        this metadata reports false (or is absent).
> +
> +        One example of this would be when the camera system starts. It may be
> +        trying to adapt very quickly to the ambient conditions, resulting in a
> +        few frames where the image brightness may be subject to unusually
> +        extreme oscillations.
> +
> +        The control may report true at other times, for example when an HDR mode
> +        is enabled. Here too there may be a few frames of unpredictable exposure
> +        until the algorithms have settled.
> +
> +        The value false (or absence of the control) indicates that this is a
> +        normal frame.
> +
>    # ----------------------------------------------------------------------------
>    # Draft controls section
>
> --
> 2.30.2
>