[libcamera-devel] [PATCH v6 1/6] libcamera: controls: Add sensor test pattern mode

[Hirokazu Honda]

Hi Laurent,

On Mon, Jun 7, 2021 at 9:01 AM Laurent Pinchart <
laurent.pinchart at ideasonboard.com> wrote:

> Hi Hiro,
>
> Thank you for the patch.
>
> On Fri, May 28, 2021 at 12:05:26PM +0900, Hirokazu Honda wrote:
> > The control is used to report available sensor test pattern modes
> > and also specify the mode to sensor.
> >
> > Signed-off-by: Hirokazu Honda <hiroh at chromium.org>
> > Reviewed-by: Jacopo Mondi <jacopo at jmondi.org>
> > ---
> >  src/libcamera/control_ids.yaml | 58 ++++++++++++++++++++++++++++++++++
> >  1 file changed, 58 insertions(+)
> >
> > diff --git a/src/libcamera/control_ids.yaml
> b/src/libcamera/control_ids.yaml
> > index 88d81ac4..b1fe1dc6 100644
> > --- a/src/libcamera/control_ids.yaml
> > +++ b/src/libcamera/control_ids.yaml
> > @@ -615,4 +615,62 @@ controls:
> >          detection, additional format conversions etc) count as an
> additional
> >          pipeline stage.
> >
> > +  - TestPatternMode:
> > +      type: int32_t
> > +      draft: true
> > +      description: |
> > +        Control to select the test pattern mode. Currently identical to
> > +        ANDROID_SENSOR_TEST_PATTERN_MODE.
>
> I'd add that the test pattern modes are identical to the ones defined by
> the CCS specification. Maybe something along the lines of:
>
>         The modes are described in a pixel-perfect way in the MIPI
>         Camera Command Set (
> https://www.mipi.org/specifications/camera-command-set)
>         specification.
>
> I've wondered for a long time how we could standardize test pattern
> modes when there's no standard at the hardware level, and I've been
> pointed out recently to the fact that CCS defines pixel-perfect test
> patterns (they are parametrized by a set of read-only parameters
> reported by the sensor though, the specification is worth a read). This
> comes from the SMIA++ specification that also standardized test pattern
> modes, but from what I've been told, not in a pixel-perfect way.
>
>
Thanks Laurent for the info. The test pattern modes defined in CCS is
almost one-to-one correspondence to Android test pattern modes though 100%
color tile is not defined in Android.
To test the test pattern modes in a pixel-perfect way, we have to tell a
client the parameters.
I am fine to re-declare the test pattern mode control based on CCS
definition, but testing them in a pixel-perfect way seems to require much
more work.

Regards,
-Hiro

> Apart from that, this looks good to me for now as it's a draft control.
> We'll have to decide how to handle custom patterns once we destage this
> control.
>
> > +      enum:
> > +        - name: TestPatternModeOff
> > +          value: 0
> > +          description: |
> > +            No test pattern mode is used. The camera device returns
> frames from
> > +            the image sensor.
> > +        - name: TestPatternModeSolidColor
> > +          value: 1
> > +          description: |
> > +            Each pixel in [R, G_even, G_odd, B] is replaced by its
> respective
> > +            color channel provided in test pattern data.
> > +            \todo Add control for test pattern data.
> > +        - name: TestPatternModeColorBars
> > +          value: 2
> > +          description: |
> > +            All pixel data is replaced with an 8-bar color pattern. The
> vertical
> > +            bars (left-to-right) are as follows; white, yellow, cyan,
> green,
> > +            magenta, red, blue and black. Each bar should take up 1/8
> of the
> > +            sensor pixel array width. When this is not possible, the
> bar size
> > +            should be rounded down to the nearest integer and the
> pattern can
> > +            repeat on the right side. Each bar's height must always
> take up the
> > +            full sensor pixel array height.
> > +        - name: TestPatternModeColorBarsFadeToGray
> > +          value: 3
> > +          description: |
> > +            The test pattern is similar to TestPatternModeColorBars,
> > +            except that each bar should start at its specified color at
> the top
> > +            and fade to gray at the bottom. Furthermore each bar is
> further
> > +            subdevided into a left and right half. The left half should
> have a
> > +            smooth gradient, and the right half should have a quantized
> > +            gradient. In particular, the right half's should consist of
> blocks
> > +            of the same color for 1/16th active sensor pixel array
> width. The
> > +            least significant bits in the quantized gradient should be
> copied
> > +            from the most significant bits of the smooth gradient. The
> height of
> > +            each bar should always be a multiple of 128. When this is
> not the
> > +            case, the pattern should repeat at the bottom of the image.
> > +        - name: TestPatternModePn9
> > +          value: 4
> > +          description: |
> > +            All pixel data is replaced by a pseudo-random sequence
> generated
> > +            from a PN9 512-bit sequence (typically implemented in
> hardware with
> > +            a linear feedback shift register). The generator should be
> reset at
> > +            the beginning of each frame, and thus each subsequent raw
> frame with
> > +            this test pattern should be exactly the same as the last.
> > +        - name: TestPatternModeCustom1
> > +          value: 5
>
> This starts at 256 in the Android camera HAL API, I'd do the same as the
> control is documented as being identical to
> ANDROID_SENSOR_TEST_PATTERN_MODE.
>
> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
>
> > +          description: |
> > +            The first custom test pattern. All custom patterns that are
> > +            available only on this camera device are at least this
> numeric
> > +            value. All of the custom test patterns will be static (that
> is the
> > +            raw image must not vary from frame to frame).
> > +
> >  ...
>
> --
> Regards,
>
> Laurent Pinchart
>
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