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ipa: simple: data: Add an OV02C10 tuning file
The simple IPA applies a colour correction matrix only when the tuning file
asks for it, and there is no tuning file for the OV02C10, so the front camera
of the Surface Pro 12in falls back to uncalibrated.yaml:
WARN IPAProxy ipa_proxy.cpp:196 Configuration file 'ov02c10.yaml' not found for IPA module 'simple', falling back to '/usr/share/libcamera/ipa/simple/uncalibrated.yaml'
That leaves the CCM at identity, i.e. the raw sensor channels are displayed as
if they were sRGB. The grey-world AWB does balance the frame, so the preview is
not tinted on average -- captured through PipeWire on this board it measures
R/G 1.03 and B/G 0.98 -- but it is flat: mean HSV saturation 0.07, with 94% of
the pixels below 0.15. Skin therefore lands close to grey and reads cyan.
Add a tuning file that enables Ccm with a hand-tuned matrix whose blue row sums
to 0.85, both to restore saturation and to take the cool edge off what the
grey-world AWB leaves behind. It is not lab-calibrated, and the file says so.
--- /dev/null
+++ b/src/ipa/simple/data/ov02c10.yaml
@@ -0,0 +1,47 @@
+# SPDX-License-Identifier: CC0-1.0
+#
+# Software ISP tuning for the OV02C10 front camera of the Microsoft Surface
+# Pro 12in.
+#
+# With no tuning file the simple IPA falls back to uncalibrated.yaml, which
+# runs no CCM: the raw sensor channels are handed to the display as though they
+# were already sRGB. The grey-world AWB still balances the frame on average, so
+# the preview is not tinted overall -- measured on this board its mean channel
+# ratios are R/G 1.03 and B/G 0.98 -- it is flat, with a mean HSV saturation of
+# 0.07 and 94% of the pixels below 0.15. What little colour survives reads
+# cool, and that is what makes skin look cyan.
+#
+# The matrix below is hand-tuned, not measured against a colour target. Its
+# off-diagonal terms undo part of the CFA crosstalk and so restore saturation,
+# and its blue row sums to 0.85 rather than 1.0, taking 15% out of blue to
+# counter the cool cast the grey-world AWB leaves behind. It comes from the
+# Samsung Galaxy Book OV02C10 work, which met the same sensor on the same
+# software ISP:
+#
+# https://github.com/hfb0/galaxy-book-ipu6-ov02c10-linux
+#
+# Both entries carry the same matrix, so nothing is interpolated over colour
+# temperature. There is no measured data to justify two different ones.
+#
+# The black level is deliberately not repeated here. The CameraSensorHelper
+# added by 0001-libipa-camera_sensor-add-ov02c10.patch already reports 0x40 at
+# 10 bits, which is what a dark frame off the CAMSS RDI node measures, and one
+# source for it is enough.
+#
+# Enabling Ccm also exposes the Saturation control, and costs nothing
+# noticeable here because the software ISP debayers on the GPU.
+%YAML 1.1
+---
+version: 1
+algorithms:
+ - BlackLevel:
+ - Awb:
+ - Ccm:
+ ccms:
+ - ct: 2860
+ ccm: [ 1.35, -0.20, -0.15, -0.15, 1.30, -0.15, -0.05, -0.20, 1.10 ]
+ - ct: 6500
+ ccm: [ 1.35, -0.20, -0.15, -0.15, 1.30, -0.15, -0.05, -0.20, 1.10 ]
+ - Adjust:
+ - Agc:
+...
--- 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([
+ 'ov02c10.yaml',
'uncalibrated.yaml',
])
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