[PATCH v4 1/3] libcamera: Add gamma control id

[Stefan Klug]

Hi Kieran,

On Wed, Jun 05, 2024 at 11:45:58AM +0100, Kieran Bingham wrote:
> Quoting Stefan Klug (2024-06-05 10:53:49)
> > A camera gamma of roughly 2.2 is necessary to produce correct output
> > images on a standard monitor. Add a control for that.
> > 
> > Further information is available here:
> > https://en.wikipedia.org/wiki/SRGB
> > https://www.cambridgeincolour.com/tutorials/gamma-correction.htm
> > 
> > Signed-off-by: Stefan Klug <stefan.klug at ideasonboard.com>
> > Reviewed-by: Daniel Scally <dan.scally at ideasonboard.com>
> > Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> > ---
> >  src/libcamera/control_ids_core.yaml | 7 +++++++
> >  1 file changed, 7 insertions(+)
> > 
> > diff --git a/src/libcamera/control_ids_core.yaml b/src/libcamera/control_ids_core.yaml
> > index bf1f1a839f6a..303b0d32e020 100644
> > --- a/src/libcamera/control_ids_core.yaml
> > +++ b/src/libcamera/control_ids_core.yaml
> > @@ -243,6 +243,13 @@ controls:
> >          Specify a fixed contrast parameter. Normal contrast is given by the
> >          value 1.0; larger values produce images with more contrast.
> >  
> > +  - Gamma:
> > +      type: float
> > +      description:  |
> > +        Specify a fixed gamma value. Default must be 2.2 which closely mimics 
> > +        sRGB gamma. Note that this is camera gamma, so it is applied as 
> > +        1.0/gamma
> > +
> 
> Aha - one small issue here.
> 
> Can you append the control instead of adding it in alphabetically?
> (Yeah, normally we'd definitely sort things alphabetically...)
> 
> That will prevent an ABI breakage. I think we can run a sort operation
> on any occasion where we do an ABI breaking release - but hopefully
> there's no need to introduce an ABI break here.

I wasn't aware of that. Changed it locally. Will be fixed when applying.

Cheers,
Stefan

> 
> --
> Kieran
> 
> 
> >    - Lux:
> >        type: float
> >        description: |
> > -- 
> > 2.43.0
> >