| Message ID | 20260225221859.600869-3-floss@jetm.me |
|---|---|
| State | Superseded |
| Headers | show |
| Series |
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| Related | show |
Hi Javier, thank you for the patch, tuning files are much needed. Javier Tia <floss@jetm.me> writes: > Add a sensor-specific tuning file for the OmniVision OV2740, commonly > found in Intel IPU6 laptops (ThinkPad X1 Carbon, XPS, Surface). > > The tuning enables all Simple IPA algorithms including AGC, AWB, black > level correction, and a color correction matrix calibrated for 6500K. > The CCM compensates for the green bias inherent in Bayer demosaicing > (the GRBG pattern has 2x green pixels vs red/blue). > > Without this file, libcamera falls back to uncalibrated.yaml which > produces a heavy green tint on the OV2740. I wonder what's the cause of the green tint really. I'm not sure I understand the Bayer pattern argument: Software ISP uses the grey world white balance algorithm that basically takes a look at average colour channel values; how many pixels represent each of the colours doesn't have direct influence on the averages. If there is a strong tint then something may be wrong. Or it's perhaps a property of the sensor. We know the current processing has flaws and it's a priority to get them fixed. Understanding the current problems would help. There may be other variables like incorrect black level (which is auto-guessed when its value is not specified in the tuning file) or its incorrect handling. > Signed-off-by: Javier Tia <floss@jetm.me> > --- > src/ipa/simple/data/meson.build | 1 + > src/ipa/simple/data/ov2740.yaml | 22 ++++++++++++++++++++++ > 2 files changed, 23 insertions(+) > create mode 100644 src/ipa/simple/data/ov2740.yaml > > diff --git a/src/ipa/simple/data/meson.build b/src/ipa/simple/data/meson.build > index 92795ee4..e3e4de74 100644 > --- a/src/ipa/simple/data/meson.build > +++ b/src/ipa/simple/data/meson.build > @@ -1,6 +1,7 @@ > # SPDX-License-Identifier: CC0-1.0 > > conf_files = files([ > + 'ov2740.yaml', > 'uncalibrated.yaml', > ]) > > diff --git a/src/ipa/simple/data/ov2740.yaml b/src/ipa/simple/data/ov2740.yaml > new file mode 100644 > index 00000000..b48d50ce > --- /dev/null > +++ b/src/ipa/simple/data/ov2740.yaml > @@ -0,0 +1,22 @@ > +# SPDX-License-Identifier: CC0-1.0 > +# > +# OmniVision OV2740 tuning for libcamera Simple/SoftISP pipeline. > +# > +# Tested on ThinkPad X1 Carbon Gen 10 (Alder Lake) with Intel IPU6 ISYS. > +# The CCM corrects the green bias inherent in Bayer demosaicing (2:1 green > +# to red/blue pixel ratio in the CFA). Values were iteratively calibrated > +# from captured frame measurements under 6500K lighting. > +%YAML 1.1 > +--- > +version: 1 > +algorithms: > + - BlackLevel: > + - Awb: > + - Ccm: > + ccms: > + - ct: 6500 > + ccm: [ 2.49, -0.91, -0.26, > + -0.30, 1.20, 0.10, > + 0.07, -0.80, 2.19 ] > + - Adjust: > + - Agc:
Hi, very happy to see this! On 26.02.26 13:28, Milan Zamazal wrote: > Hi Javier, > > thank you for the patch, tuning files are much needed. > > Javier Tia<floss@jetm.me> writes: > >> Add a sensor-specific tuning file for the OmniVision OV2740, commonly >> found in Intel IPU6 laptops (ThinkPad X1 Carbon, XPS, Surface). >> >> The tuning enables all Simple IPA algorithms including AGC, AWB, black >> level correction, and a color correction matrix calibrated for 6500K. >> The CCM compensates for the green bias inherent in Bayer demosaicing >> (the GRBG pattern has 2x green pixels vs red/blue). >> >> Without this file, libcamera falls back to uncalibrated.yaml which >> produces a heavy green tint on the OV2740. > I wonder what's the cause of the green tint really. I'm not sure I > understand the Bayer pattern argument: Software ISP uses the grey world > white balance algorithm that basically takes a look at average colour > channel values; how many pixels represent each of the colours doesn't > have direct influence on the averages. If there is a strong tint then > something may be wrong. Or it's perhaps a property of the sensor. We > know the current processing has flaws and it's a priority to get them > fixed. Understanding the current problems would help. > > There may be other variables like incorrect black level (which is > auto-guessed when its value is not specified in the tuning file) or its > incorrect handling. Just a note regarding black level: this should be taken from the CameraSensorHelper if possible. There is already CameraSensorHelperOv2740, however it's missing a blackLevel_ value - it would be great to add that as part of this series. Regards, Robert >> Signed-off-by: Javier Tia<floss@jetm.me> >> --- >> src/ipa/simple/data/meson.build | 1 + >> src/ipa/simple/data/ov2740.yaml | 22 ++++++++++++++++++++++ >> 2 files changed, 23 insertions(+) >> create mode 100644 src/ipa/simple/data/ov2740.yaml >> >> diff --git a/src/ipa/simple/data/meson.build b/src/ipa/simple/data/meson.build >> index 92795ee4..e3e4de74 100644 >> --- a/src/ipa/simple/data/meson.build >> +++ b/src/ipa/simple/data/meson.build >> @@ -1,6 +1,7 @@ >> # SPDX-License-Identifier: CC0-1.0 >> >> conf_files = files([ >> + 'ov2740.yaml', >> 'uncalibrated.yaml', >> ]) >> >> diff --git a/src/ipa/simple/data/ov2740.yaml b/src/ipa/simple/data/ov2740.yaml >> new file mode 100644 >> index 00000000..b48d50ce >> --- /dev/null >> +++ b/src/ipa/simple/data/ov2740.yaml >> @@ -0,0 +1,22 @@ >> +# SPDX-License-Identifier: CC0-1.0 >> +# >> +# OmniVision OV2740 tuning for libcamera Simple/SoftISP pipeline. >> +# >> +# Tested on ThinkPad X1 Carbon Gen 10 (Alder Lake) with Intel IPU6 ISYS. >> +# The CCM corrects the green bias inherent in Bayer demosaicing (2:1 green >> +# to red/blue pixel ratio in the CFA). Values were iteratively calibrated >> +# from captured frame measurements under 6500K lighting. >> +%YAML 1.1 >> +--- >> +version: 1 >> +algorithms: >> + - BlackLevel: >> + - Awb: >> + - Ccm: >> + ccms: >> + - ct: 6500 >> + ccm: [ 2.49, -0.91, -0.26, >> + -0.30, 1.20, 0.10, >> + 0.07, -0.80, 2.19 ] >> + - Adjust: >> + - Agc:
Quoting Milan Zamazal (2026-02-26 12:28:44) > Hi Javier, > > thank you for the patch, tuning files are much needed. > > Javier Tia <floss@jetm.me> writes: > > > Add a sensor-specific tuning file for the OmniVision OV2740, commonly > > found in Intel IPU6 laptops (ThinkPad X1 Carbon, XPS, Surface). > > > > The tuning enables all Simple IPA algorithms including AGC, AWB, black > > level correction, and a color correction matrix calibrated for 6500K. > > The CCM compensates for the green bias inherent in Bayer demosaicing > > (the GRBG pattern has 2x green pixels vs red/blue). > > > > Without this file, libcamera falls back to uncalibrated.yaml which > > produces a heavy green tint on the OV2740. > > I wonder what's the cause of the green tint really. I'm not sure I > understand the Bayer pattern argument: Software ISP uses the grey world > white balance algorithm that basically takes a look at average colour > channel values; how many pixels represent each of the colours doesn't > have direct influence on the averages. If there is a strong tint then > something may be wrong. Or it's perhaps a property of the sensor. We Somebody gave a talk about that quite recently: - https://video.fosdem.org/2026/ud2120/BQJPUP-libcamera-tuning.av1.webm > know the current processing has flaws and it's a priority to get them > fixed. Understanding the current problems would help. > > There may be other variables like incorrect black level (which is > auto-guessed when its value is not specified in the tuning file) or its > incorrect handling. > > > Signed-off-by: Javier Tia <floss@jetm.me> > > --- > > src/ipa/simple/data/meson.build | 1 + > > src/ipa/simple/data/ov2740.yaml | 22 ++++++++++++++++++++++ > > 2 files changed, 23 insertions(+) > > create mode 100644 src/ipa/simple/data/ov2740.yaml > > > > diff --git a/src/ipa/simple/data/meson.build b/src/ipa/simple/data/meson.build > > index 92795ee4..e3e4de74 100644 > > --- a/src/ipa/simple/data/meson.build > > +++ b/src/ipa/simple/data/meson.build > > @@ -1,6 +1,7 @@ > > # SPDX-License-Identifier: CC0-1.0 > > > > conf_files = files([ > > + 'ov2740.yaml', > > 'uncalibrated.yaml', > > ]) > > > > diff --git a/src/ipa/simple/data/ov2740.yaml b/src/ipa/simple/data/ov2740.yaml > > new file mode 100644 > > index 00000000..b48d50ce > > --- /dev/null > > +++ b/src/ipa/simple/data/ov2740.yaml > > @@ -0,0 +1,22 @@ > > +# SPDX-License-Identifier: CC0-1.0 > > +# > > +# OmniVision OV2740 tuning for libcamera Simple/SoftISP pipeline. > > +# > > +# Tested on ThinkPad X1 Carbon Gen 10 (Alder Lake) with Intel IPU6 ISYS. > > +# The CCM corrects the green bias inherent in Bayer demosaicing (2:1 green > > +# to red/blue pixel ratio in the CFA). Values were iteratively calibrated > > +# from captured frame measurements under 6500K lighting. > > +%YAML 1.1 > > +--- > > +version: 1 > > +algorithms: > > + - BlackLevel: > > + - Awb: > > + - Ccm: > > + ccms: > > + - ct: 6500 > > + ccm: [ 2.49, -0.91, -0.26, > > + -0.30, 1.20, 0.10, > > + 0.07, -0.80, 2.19 ] It's actually important that these add up to '1' in each row. Otherwise it's applying an artificial gain as well. The talk at https://video.fosdem.org/2026/ud2120/BQJPUP-libcamera-tuning.av1.webm is precisely about dealing with how we need to capture and determine these values correctly. -- Kieran > > + - Adjust: > > + - Agc: >
Kieran Bingham <kieran.bingham@ideasonboard.com> writes: > Quoting Milan Zamazal (2026-02-26 12:28:44) >> Hi Javier, >> > >> thank you for the patch, tuning files are much needed. >> >> Javier Tia <floss@jetm.me> writes: >> >> > Add a sensor-specific tuning file for the OmniVision OV2740, commonly >> > found in Intel IPU6 laptops (ThinkPad X1 Carbon, XPS, Surface). >> > >> > The tuning enables all Simple IPA algorithms including AGC, AWB, black >> > level correction, and a color correction matrix calibrated for 6500K. >> > The CCM compensates for the green bias inherent in Bayer demosaicing >> > (the GRBG pattern has 2x green pixels vs red/blue). >> > >> > Without this file, libcamera falls back to uncalibrated.yaml which >> > produces a heavy green tint on the OV2740. >> >> I wonder what's the cause of the green tint really. I'm not sure I >> understand the Bayer pattern argument: Software ISP uses the grey world >> white balance algorithm that basically takes a look at average colour >> channel values; how many pixels represent each of the colours doesn't >> have direct influence on the averages. If there is a strong tint then >> something may be wrong. Or it's perhaps a property of the sensor. We > > Somebody gave a talk about that quite recently: > - https://video.fosdem.org/2026/ud2120/BQJPUP-libcamera-tuning.av1.webm Nice and very useful talk! As for the green tint, it explains why it's present in images without adjustments. But white balance should compensate for it, shouldn't it? Sure, there would be other colour problems without the CCM, perhaps even some greenish look, and the current software ISP white balance is also far from perfect, but I wouldn't expect getting heavy green tint consistently. Maybe it is what it is but it still looks suspicious to me. >> know the current processing has flaws and it's a priority to get them >> fixed. Understanding the current problems would help. >> >> There may be other variables like incorrect black level (which is >> auto-guessed when its value is not specified in the tuning file) or its >> incorrect handling. >> >> > Signed-off-by: Javier Tia <floss@jetm.me> >> > --- >> > src/ipa/simple/data/meson.build | 1 + >> > src/ipa/simple/data/ov2740.yaml | 22 ++++++++++++++++++++++ >> > 2 files changed, 23 insertions(+) >> > create mode 100644 src/ipa/simple/data/ov2740.yaml >> > >> > diff --git a/src/ipa/simple/data/meson.build b/src/ipa/simple/data/meson.build >> > index 92795ee4..e3e4de74 100644 >> > --- a/src/ipa/simple/data/meson.build >> > +++ b/src/ipa/simple/data/meson.build >> > @@ -1,6 +1,7 @@ >> > # SPDX-License-Identifier: CC0-1.0 >> > >> > conf_files = files([ >> > + 'ov2740.yaml', >> > 'uncalibrated.yaml', >> > ]) >> > >> > diff --git a/src/ipa/simple/data/ov2740.yaml b/src/ipa/simple/data/ov2740.yaml >> > new file mode 100644 >> > index 00000000..b48d50ce >> > --- /dev/null >> > +++ b/src/ipa/simple/data/ov2740.yaml >> > @@ -0,0 +1,22 @@ >> > +# SPDX-License-Identifier: CC0-1.0 >> > +# >> > +# OmniVision OV2740 tuning for libcamera Simple/SoftISP pipeline. >> > +# >> > +# Tested on ThinkPad X1 Carbon Gen 10 (Alder Lake) with Intel IPU6 ISYS. >> > +# The CCM corrects the green bias inherent in Bayer demosaicing (2:1 green >> > +# to red/blue pixel ratio in the CFA). Values were iteratively calibrated >> > +# from captured frame measurements under 6500K lighting. >> > +%YAML 1.1 >> > +--- >> > +version: 1 >> > +algorithms: >> > + - BlackLevel: >> > + - Awb: >> > + - Ccm: >> > + ccms: >> > + - ct: 6500 >> > + ccm: [ 2.49, -0.91, -0.26, >> > + -0.30, 1.20, 0.10, >> > + 0.07, -0.80, 2.19 ] > > It's actually important that these add up to '1' in each row. Otherwise > it's applying an artificial gain as well. > > The talk at > https://video.fosdem.org/2026/ud2120/BQJPUP-libcamera-tuning.av1.webm is > precisely about dealing with how we need to capture and determine these > values correctly. > > -- > Kieran > > >> > + - Adjust: >> > + - Agc: >>
Robert Mader <robert.mader@collabora.com> writes: > Hi, very happy to see this! > > On 26.02.26 13:28, Milan Zamazal wrote: >> Hi Javier, >> >> thank you for the patch, tuning files are much needed. >> Javier Tia<floss@jetm.me> writes: >> >>> Add a sensor-specific tuning file for the OmniVision OV2740, commonly found in Intel IPU6 laptops (ThinkPad X1 Carbon, XPS, Surface). >>> The tuning enables all Simple IPA algorithms including AGC, AWB, black level correction, and a color correction matrix calibrated for 6500K. The CCM compensates for the green bias inherent in Bayer demosaicing (the GRBG pattern has 2x green pixels vs red/blue). >>> Without this file, libcamera falls back to uncalibrated.yaml which produces a heavy green tint on the OV2740. >> I wonder what's the cause of the green tint really. I'm not sure I understand the Bayer pattern argument: Software ISP uses the grey world white balance algorithm that basically takes a look at average colour channel values; how many pixels represent each of the colours doesn't have direct influence on the averages. If there is a strong tint then something may be wrong. Or it's perhaps a property of the sensor. We know the current processing has flaws and it's a priority to get them fixed. Understanding the current problems would help. >> There may be other variables like incorrect black level (which is auto-guessed when its value is not specified in the tuning file) or its >> incorrect handling. > > Just a note regarding black level: this should be taken from the > CameraSensorHelper if possible. Indeed, thank you for the correction. Normally, the value should be specified in the sensor helper. It can be specified in the tuning file in the following cases: - A user wants to use a different black level. - There is a sensor without known gains but with a known black level. Because a camera sensor helper cannot be defined without specifying gains, the only way to specify the black level is using the tuning file. > There is already CameraSensorHelperOv2740, however it's missing a > blackLevel_ value - it would be great to add that as part of this > series. > > Regards, > > Robert > >>> Signed-off-by: Javier Tia<floss@jetm.me> --- >>> src/ipa/simple/data/meson.build | 1 + src/ipa/simple/data/ov2740.yaml | 22 ++++++++++++++++++++++ 2 files changed, 23 insertions(+) create mode 100644 src/ipa/simple/data/ov2740.yaml >>> diff --git a/src/ipa/simple/data/meson.build b/src/ipa/simple/data/meson.build index 92795ee4..e3e4de74 100644 --- a/src/ipa/simple/data/meson.build +++ b/src/ipa/simple/data/meson.build @@ -1,6 +1,7 @@ # SPDX-License-Identifier: CC0-1.0 conf_files = files([ + 'ov2740.yaml', 'uncalibrated.yaml', ]) diff --git a/src/ipa/simple/data/ov2740.yaml b/src/ipa/simple/data/ov2740.yaml new file mode 100644 index 00000000..b48d50ce --- /dev/null +++ b/src/ipa/simple/data/ov2740.yaml @@ -0,0 +1,22 @@ +# SPDX-License-Identifier: CC0-1.0 +# +# OmniVision OV2740 tuning for libcamera Simple/SoftISP pipeline. +# +# Tested on ThinkPad X1 Carbon Gen 10 (Alder Lake) with Intel IPU6 ISYS. +# The CCM corrects the green bias inherent in Bayer demosaicing (2:1 green +# to red/blue pixel ratio in the CFA). Values were iteratively calibrated +# from captured frame measurements under 6500K lighting. +%YAML 1.1 +--- +version: 1 +algorithms: + - BlackLevel: + - Awb: + - Ccm: + ccms: + - ct: 6500 + ccm: [ 2.49, -0.91, -0.26, + -0.30, 1.20, 0.10, + 0.07, -0.80, 2.19 ] + - Adjust: + - Agc:
diff --git a/src/ipa/simple/data/meson.build b/src/ipa/simple/data/meson.build index 92795ee4..e3e4de74 100644 --- a/src/ipa/simple/data/meson.build +++ b/src/ipa/simple/data/meson.build @@ -1,6 +1,7 @@ # SPDX-License-Identifier: CC0-1.0 conf_files = files([ + 'ov2740.yaml', 'uncalibrated.yaml', ]) diff --git a/src/ipa/simple/data/ov2740.yaml b/src/ipa/simple/data/ov2740.yaml new file mode 100644 index 00000000..b48d50ce --- /dev/null +++ b/src/ipa/simple/data/ov2740.yaml @@ -0,0 +1,22 @@ +# SPDX-License-Identifier: CC0-1.0 +# +# OmniVision OV2740 tuning for libcamera Simple/SoftISP pipeline. +# +# Tested on ThinkPad X1 Carbon Gen 10 (Alder Lake) with Intel IPU6 ISYS. +# The CCM corrects the green bias inherent in Bayer demosaicing (2:1 green +# to red/blue pixel ratio in the CFA). Values were iteratively calibrated +# from captured frame measurements under 6500K lighting. +%YAML 1.1 +--- +version: 1 +algorithms: + - BlackLevel: + - Awb: + - Ccm: + ccms: + - ct: 6500 + ccm: [ 2.49, -0.91, -0.26, + -0.30, 1.20, 0.10, + 0.07, -0.80, 2.19 ] + - Adjust: + - Agc:
Add a sensor-specific tuning file for the OmniVision OV2740, commonly found in Intel IPU6 laptops (ThinkPad X1 Carbon, XPS, Surface). The tuning enables all Simple IPA algorithms including AGC, AWB, black level correction, and a color correction matrix calibrated for 6500K. The CCM compensates for the green bias inherent in Bayer demosaicing (the GRBG pattern has 2x green pixels vs red/blue). Without this file, libcamera falls back to uncalibrated.yaml which produces a heavy green tint on the OV2740. Signed-off-by: Javier Tia <floss@jetm.me> --- src/ipa/simple/data/meson.build | 1 + src/ipa/simple/data/ov2740.yaml | 22 ++++++++++++++++++++++ 2 files changed, 23 insertions(+) create mode 100644 src/ipa/simple/data/ov2740.yaml