| Message ID | 20210902115135.62199-1-jeanmichel.hautbois@ideasonboard.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series |
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| Related | show |
On 02/09/2021 12:51, Jean-Michel Hautbois wrote: > The AWB algorithm is based on the Grey world algorithm and uses the > statistics generated by the ImgU for that. Explain how it uses those, > and reference the original algorithm at the same time. > > Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com> > --- > src/ipa/ipu3/algorithms/awb.cpp | 26 ++++++++++++++++++++++++++ > 1 file changed, 26 insertions(+) > > diff --git a/src/ipa/ipu3/algorithms/awb.cpp b/src/ipa/ipu3/algorithms/awb.cpp > index d97724fa..f0b12d1a 100644 > --- a/src/ipa/ipu3/algorithms/awb.cpp > +++ b/src/ipa/ipu3/algorithms/awb.cpp > @@ -20,6 +20,32 @@ LOG_DEFINE_CATEGORY(IPU3Awb) > static constexpr uint32_t kMinZonesCounted = 16; > static constexpr uint32_t kMinGreenLevelInZone = 32; > > +/** > + * The Grey World algorithm assumes that the scene, in average, is neutral grey. > + * Reference: Lam, Edmund & Fung, George. (2008). Automatic White Balancing in > + * Digital Photography. 10.1201/9781420054538.ch10. Does this mean that /this/ algorithm is an implementation of the Grey World algorithm? We should say so. """ This AWB algorithm module provides a simple Grey World algorithm implementation based upon the procedures and methods described in Automatic White Balancing in Digital Photography. The Grey World algorithm assumes that the scene, in average, is a neutral grey. Reference: Lam, Edmund & Fung, George. (2008). Automatic White Balancing in Digital Photography. 10.1201/9781420054538.ch10. """ > + * > + * The IPU3 generates statistics from the Bayer Down Scaler output into a grid > + * defined in the ipu3_uapi_awb_config_s structure. > + * > + * For example, when the BDS outputs a frame of 2592x1944, the grid may be > + * configured to 81x30 cells each with a size of 32x64 pixels. > + * We then have an average of 2048 R, G and B pixels per cell. > + * > + * The AWB algorithm uses a fixed grid size of kAwbStatsSizeX x kAwbStatsSizeY. "This AWB algorithm" ? But otherwise, Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com> > + * Each of this new grid cell will be called a zone. > + * > + * Before calculating the gains, we will convert the statistics from the BDS > + * grid to an internal grid configuration in generateAwbStats. > + * As part of converting the statistics to an internal grid, the saturation > + * flag from the originating grid cell is used to decide if the zone contains > + * saturated pixels or not, making the zone relevant or not. > + * A saturated zone will be excluded from the calculation. > + * > + * The Grey World algorithm will then estimate the red and blue gains to apply, and > + * store the results in the metadata. > + */ > + > /** > * \struct Accumulator > * \brief RGB statistics for a given region >
diff --git a/src/ipa/ipu3/algorithms/awb.cpp b/src/ipa/ipu3/algorithms/awb.cpp index d97724fa..f0b12d1a 100644 --- a/src/ipa/ipu3/algorithms/awb.cpp +++ b/src/ipa/ipu3/algorithms/awb.cpp @@ -20,6 +20,32 @@ LOG_DEFINE_CATEGORY(IPU3Awb) static constexpr uint32_t kMinZonesCounted = 16; static constexpr uint32_t kMinGreenLevelInZone = 32; +/** + * The Grey World algorithm assumes that the scene, in average, is neutral grey. + * Reference: Lam, Edmund & Fung, George. (2008). Automatic White Balancing in + * Digital Photography. 10.1201/9781420054538.ch10. + * + * The IPU3 generates statistics from the Bayer Down Scaler output into a grid + * defined in the ipu3_uapi_awb_config_s structure. + * + * For example, when the BDS outputs a frame of 2592x1944, the grid may be + * configured to 81x30 cells each with a size of 32x64 pixels. + * We then have an average of 2048 R, G and B pixels per cell. + * + * The AWB algorithm uses a fixed grid size of kAwbStatsSizeX x kAwbStatsSizeY. + * Each of this new grid cell will be called a zone. + * + * Before calculating the gains, we will convert the statistics from the BDS + * grid to an internal grid configuration in generateAwbStats. + * As part of converting the statistics to an internal grid, the saturation + * flag from the originating grid cell is used to decide if the zone contains + * saturated pixels or not, making the zone relevant or not. + * A saturated zone will be excluded from the calculation. + * + * The Grey World algorithm will then estimate the red and blue gains to apply, and + * store the results in the metadata. + */ + /** * \struct Accumulator * \brief RGB statistics for a given region
The AWB algorithm is based on the Grey world algorithm and uses the statistics generated by the ImgU for that. Explain how it uses those, and reference the original algorithm at the same time. Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com> --- src/ipa/ipu3/algorithms/awb.cpp | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+)