| Message ID | 20220617084519.32129-1-jeanmichel.hautbois@ideasonboard.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | media: staging: ipu3-imgu: Fix BNR wb gain documentation | expand |
Hi JM, Quoting Jean-Michel Hautbois (2022-06-17 09:45:19) > The documentation states that the BNR factor is a multiplier coded as > u3.13 and with a range of (0, 8). This is not correct, as the isp is > adding 1.0 to the gain applied, ie Pout = { Pin * (1 + Gx) }. > > It means that a gain of 1.0 should be coded as 0. > > Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com> > --- > drivers/staging/media/ipu3/include/uapi/intel-ipu3.h | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/drivers/staging/media/ipu3/include/uapi/intel-ipu3.h b/drivers/staging/media/ipu3/include/uapi/intel-ipu3.h > index dbdd015ce220..caa358e0bae4 100644 > --- a/drivers/staging/media/ipu3/include/uapi/intel-ipu3.h > +++ b/drivers/staging/media/ipu3/include/uapi/intel-ipu3.h > @@ -626,8 +626,11 @@ struct ipu3_uapi_stats_3a { > * @b: white balance gain for B channel. > * @gb: white balance gain for Gb channel. > * > - * Precision u3.13, range [0, 8). White balance correction is done by applying > - * a multiplicative gain to each color channels prior to BNR. > + * For BNR parameters WB gain factor for the three channels [Ggr, Ggb, Gb, Gr]. As with the equivalent change on the libcamera IPA side, there are 4 channels, and the text could be updated to match I think. With that done: Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com> > + * Their precision is U3.13 and the range is (0, 8) and the actual gain is > + * Gx + 1, it is typically Gx = 1. > + * > + * Pout = {Pin * (1 + Gx)}. > */ > struct ipu3_uapi_bnr_static_config_wb_gains_config { > __u16 gr; > -- > 2.34.1 >
diff --git a/drivers/staging/media/ipu3/include/uapi/intel-ipu3.h b/drivers/staging/media/ipu3/include/uapi/intel-ipu3.h index dbdd015ce220..caa358e0bae4 100644 --- a/drivers/staging/media/ipu3/include/uapi/intel-ipu3.h +++ b/drivers/staging/media/ipu3/include/uapi/intel-ipu3.h @@ -626,8 +626,11 @@ struct ipu3_uapi_stats_3a { * @b: white balance gain for B channel. * @gb: white balance gain for Gb channel. * - * Precision u3.13, range [0, 8). White balance correction is done by applying - * a multiplicative gain to each color channels prior to BNR. + * For BNR parameters WB gain factor for the three channels [Ggr, Ggb, Gb, Gr]. + * Their precision is U3.13 and the range is (0, 8) and the actual gain is + * Gx + 1, it is typically Gx = 1. + * + * Pout = {Pin * (1 + Gx)}. */ struct ipu3_uapi_bnr_static_config_wb_gains_config { __u16 gr;
The documentation states that the BNR factor is a multiplier coded as u3.13 and with a range of (0, 8). This is not correct, as the isp is adding 1.0 to the gain applied, ie Pout = { Pin * (1 + Gx) }. It means that a gain of 1.0 should be coded as 0. Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com> --- drivers/staging/media/ipu3/include/uapi/intel-ipu3.h | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)