Re: [igt-dev] [PATCH i-g-t v3 18/21] lib/igt_frame: Add a checkerboard frame comparison method

Maxime Ripard
2019-01-15T17:41:39Z

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On Mon, Jan 14, 2019 at 04:04:16PM +0100, Paul Kocialkowski wrote:
> On Fri, 2019-01-11 at 16:19 +0100, Maxime Ripard wrote:
> > On Fri, Jan 11, 2019 at 10:05:29AM +0100, Paul Kocialkowski wrote:
> > > This introduces a new frame comparison method that was designed for
> > > patterns that follow a checkerboard style. These patterns are made of
> > > consecutive rectangular shapes with alternating solid colors. They are
> > > currently used for some Chamelium-based tests.
> > >
> > > The method is particularly adapted for cases where the edges of the
> > > shapes might be blurred (e.g. due to scaling), which makes it impossible
> > > to use pixel-perfect or CRC-based comparisons to decide whether the
> > > captured frame matches the reference.
> > >
> > > Overall, this test will first detect the edges of the pattern and later
> > > exclude them from comparison. Colors are compared between the reference
> > > and capture with a low threshold for error. A percentage of the faulty
> > > pixels is calculated and the captured frame is considered invalid if
> > > more than one percent of the pixels are erroneous.
> > >
> > > Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> > > ---
> > > lib/igt_frame.c | 121 ++++++++++++++++++++++++++++++++++++++++++++++++
> > > lib/igt_frame.h | 2 +
> > > 2 files changed, 123 insertions(+)
> > >
> > > diff --git a/lib/igt_frame.c b/lib/igt_frame.c
> > > index 6984c02e9912..e0215660ea6e 100644
> > > --- a/lib/igt_frame.c
> > > +++ b/lib/igt_frame.c
> > > @@ -267,3 +267,124 @@ complete:
> > >
> > > return match;
> > > }
> > > +
> > > +#define XR24_COLOR_VALUE(data, stride, x, y, c) \
> > > + *((uint8_t *)(data) + (y) * (stride) + 4 * (x) + (c))
> > > +
> > > +/**
> > > + * igt_check_checkerboard_frame_match:
> > > + * @reference: The reference cairo surface
> > > + * @capture: The captured cairo surface
> > > + *
> > > + * Checks that the reference frame matches the captured frame using a
> > > + * method designed for checkerboard patterns. These patterns are made of
> > > + * consecutive rectangular shapes with alternating solid colors.
> > > + *
> > > + * The intent of this method is to cover cases where the captured result is
> > > + * pixel-perfect due to features such as scaling or YUV conversion and
> >
> > is *not* pixel perfect?
>
> Woops, good catch!
>
> [...]
>
> > > diff --git a/lib/igt_frame.h b/lib/igt_frame.h
> > > index 11f96cbea203..f44f57d7ce73 100644
> > > --- a/lib/igt_frame.h
> > > +++ b/lib/igt_frame.h
> > > @@ -38,5 +38,7 @@ void igt_write_compared_frames_to_png(cairo_surface_t *reference,
> > > const char *capture_suffix);
> > > bool igt_check_analog_frame_match(cairo_surface_t *reference,
> > > cairo_surface_t *capture);
> > > +bool igt_check_checkerboard_frame_match(cairo_surface_t *reference,
> > > + cairo_surface_t *capture);
> >
> > Looks good otherwise. I guess it's missing some comments about the
> > algorithm being used though.
>
> I tried to include comments where I felt was necessary, but might have
> missed out on some aspects. Or maybe you meant that the documentation
> block does not provide enough detail about the algorithm itself (as
> opposed to what it does)?

Sorry if it wasn't clear enough, that's indeed what I meant.

Maxime

--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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