[libcamera-devel] [PATCH v3 1/3] libcamera: Add support for monochrome sensors

[Laurent Pinchart]

Hi David,

Thank you for the patch.

On Fri, Jun 18, 2021 at 11:04:28PM +0100, David Plowman wrote:
> This commit adds support for monochrome (greyscale) raw sensors. These
> are sensors that have no colour filter array, so all pixels are the
> same and there are no distinct colour channels.
> 
> These sensors still require many of an ISP's processing stages, such
> as denoise, tone mapping, but not those that involve colours (such as
> demosaic, or colour matrices).

At some point we may want to rename BayerFormat to CFAPattern or
something similar, what do you think ? It's not a dependency for this
patch, so

Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

> Signed-off-by: David Plowman <david.plowman at raspberrypi.com>
> Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> ---
>  include/libcamera/internal/bayer_format.h |  3 ++-
>  src/libcamera/bayer_format.cpp            | 14 ++++++++++++--
>  src/libcamera/camera_sensor.cpp           |  3 +++
>  src/libcamera/property_ids.yaml           |  4 ++++
>  4 files changed, 21 insertions(+), 3 deletions(-)
> 
> diff --git a/include/libcamera/internal/bayer_format.h b/include/libcamera/internal/bayer_format.h
> index 5b8c1dc9..723382d4 100644
> --- a/include/libcamera/internal/bayer_format.h
> +++ b/include/libcamera/internal/bayer_format.h
> @@ -23,7 +23,8 @@ public:
>  		BGGR = 0,
>  		GBRG = 1,
>  		GRBG = 2,
> -		RGGB = 3
> +		RGGB = 3,
> +		MONO = 4
>  	};
>  
>  	enum Packing : uint16_t {
> diff --git a/src/libcamera/bayer_format.cpp b/src/libcamera/bayer_format.cpp
> index ed61202c..11355f14 100644
> --- a/src/libcamera/bayer_format.cpp
> +++ b/src/libcamera/bayer_format.cpp
> @@ -45,6 +45,8 @@ namespace libcamera {
>   * \brief G then R on the first row, B then G on the second row.
>   * \var BayerFormat::RGGB
>   * \brief R then G on the first row, G then B on the second row.
> + * \var BayerFormat::MONO
> + * \brief Monochrome image data, there is no colour filter array.
>   */
>  
>  /**
> @@ -111,6 +113,8 @@ const std::map<BayerFormat, V4L2PixelFormat, BayerFormatComparator> bayerToV4l2{
>  	{ { BayerFormat::GBRG, 16, BayerFormat::None }, V4L2PixelFormat(V4L2_PIX_FMT_SGBRG16) },
>  	{ { BayerFormat::GRBG, 16, BayerFormat::None }, V4L2PixelFormat(V4L2_PIX_FMT_SGRBG16) },
>  	{ { BayerFormat::RGGB, 16, BayerFormat::None }, V4L2PixelFormat(V4L2_PIX_FMT_SRGGB16) },
> +	{ { BayerFormat::MONO, 8, BayerFormat::None }, V4L2PixelFormat(V4L2_PIX_FMT_GREY) },
> +	{ { BayerFormat::MONO, 10, BayerFormat::CSI2Packed }, V4L2PixelFormat(V4L2_PIX_FMT_Y10P) },
>  };
>  
>  const std::unordered_map<unsigned int, BayerFormat> mbusCodeToBayer{
> @@ -146,6 +150,8 @@ const std::unordered_map<unsigned int, BayerFormat> mbusCodeToBayer{
>  	{ MEDIA_BUS_FMT_SGBRG16_1X16, { BayerFormat::GBRG, 16, BayerFormat::None } },
>  	{ MEDIA_BUS_FMT_SGRBG16_1X16, { BayerFormat::GRBG, 16, BayerFormat::None } },
>  	{ MEDIA_BUS_FMT_SRGGB16_1X16, { BayerFormat::RGGB, 16, BayerFormat::None } },
> +	{ MEDIA_BUS_FMT_Y8_1X8, { BayerFormat::MONO, 8, BayerFormat::None } },
> +	{ MEDIA_BUS_FMT_Y10_1X10, { BayerFormat::MONO, 10, BayerFormat::None } },
>  };
>  
>  } /* namespace */
> @@ -198,9 +204,10 @@ std::string BayerFormat::toString() const
>  		"BGGR",
>  		"GBRG",
>  		"GRBG",
> -		"RGGB"
> +		"RGGB",
> +		"MONO"
>  	};
> -	if (isValid() && order <= RGGB)
> +	if (isValid() && order <= MONO)
>  		result = orderStrings[order];
>  	else
>  		return "INVALID";
> @@ -280,6 +287,9 @@ BayerFormat BayerFormat::transform(Transform t) const
>  {
>  	BayerFormat result = *this;
>  
> +	if (order == MONO)
> +		return result;
> +
>  	/*
>  	 * Observe that flipping bit 0 of the Order enum performs a horizontal
>  	 * mirror on the Bayer pattern (e.g. RGGB goes to GRBG). Similarly,
> diff --git a/src/libcamera/camera_sensor.cpp b/src/libcamera/camera_sensor.cpp
> index 3e135353..fb67c15a 100644
> --- a/src/libcamera/camera_sensor.cpp
> +++ b/src/libcamera/camera_sensor.cpp
> @@ -427,6 +427,9 @@ int CameraSensor::initProperties()
>  		case BayerFormat::RGGB:
>  			cfa = properties::draft::RGGB;
>  			break;
> +		case BayerFormat::MONO:
> +			cfa = properties::draft::MONO;
> +			break;
>  		}
>  
>  		properties_.set(properties::draft::ColorFilterArrangement, cfa);
> diff --git a/src/libcamera/property_ids.yaml b/src/libcamera/property_ids.yaml
> index 104e9aaf..12ecbce5 100644
> --- a/src/libcamera/property_ids.yaml
> +++ b/src/libcamera/property_ids.yaml
> @@ -706,5 +706,9 @@ controls:
>            description: |
>              Sensor is not Bayer; output has 3 16-bit values for each pixel,
>              instead of just 1 16-bit value per pixel.
> +        - name: MONO
> +          value: 5
> +          description: |
> +            Sensor is not Bayer; output consists of a single colour channel.
>  
>  ...

-- 
Regards,

Laurent Pinchart