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Provide the requested contrast value, if any, in the metadata to add to
the completed requests.
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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This patch applies color correction matrix (CCM) in debayering if the
CCM is specified. Not using CCM must still be supported for performance
reasons.
The CCM is applied as follows:
[r1 g1 b1] [r]
[r2 g2 b2] * [g]
[r3 g3 b3] [b]
The CCM matrix (the left side of the multiplication) is constant during
single frame processing, while the input pixel (the right side) changes.
Because each of the color channels is only 8-bit in software ISP, we can
make 9 lookup tables with 256 input values for multiplications of each
of the r_i, g_i, b_i values. This way we don't have to multiply each
pixel, we can use table lookups and additions instead. Gamma (which is
non-linear and thus cannot be a part of the 9 lookup tables values) is
applied on the final values rounded to integers using another lookup
table.
Because the changing part is the pixel value with three color elements,
only three dynamic table lookups are needed. We use three lookup tables
to represent the multiplied matrix values, each of the tables
corresponding to the given matrix column and pixel color.
We use int16_t to store the precomputed multiplications. This seems to
be noticeably (>10%) faster than `float' for the price of slightly less
accuracy and it covers the range of values that sane CCMs produce. The
selection and structure of data is performance critical, for example
using bytes would add significant (>10%) speedup but would be too short
to cover the value range.
The color lookup tables can be represented either as unions,
accommodating tables for both the CCM and non-CCM cases, or as separate
tables for each of the cases, leaving the tables for the other case
unused. The latter is selected as a matter of preference.
The tables are copied (as before), which is not elegant but also not a
big problem. There are patches posted that use shared buffers for
parameters passing in software ISP (see software ISP TODO #5) and they
can be adjusted for the new parameter format.
Color gains from white balance are supposed not to be a part of the
specified CCM. They are applied on it using matrix multiplication,
which is simple and in correspondence with future additions in the form
of matrix multiplication, like saturation adjustment.
With this patch, the reported per-frame slowdown when applying CCM is
about 45% on Debix Model A and about 75% on TI AM69 SK.
Using std::clamp in debayering adds some performance penalty (a few
percent). The clamping is necessary to eliminate out of range values
possibly produced by the CCM. If it could be avoided by adjusting the
precomputed tables some way then performance could be improved a bit.
Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
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This patch introduces support for applying runtime controls to software
ISP. It enables the contrast control as the first control that can be
used.
Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
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Software ISP is currently fully automatic and doesn't allow image
modifications by explicitly set control values. The user has no means
to make the image looking better.
This patch introduces support for contrast control, which can improve
e.g. a flat looking image. Based on the provided contrast value, it
applies a simple S-curve modification to the image.
The contrast algorithm just handles the provided values, while the
S-curve is applied in the gamma algorithm on the computed gamma curve
whenever the contrast value changes. Since the algorithm is applied
only on the lookup table already present, its overhead is negligible.
The contrast value range is 0..2 and corresponds to the whole range from
a completely flat contrast to an infinite contrast, 1.0 being the normal
value. This makes the user visible range intuitive and easy to use in
GUI sliders, while complying with Contrast control definition. There is
no unified range in the hardware pipelines, for example rkisp1 uses
0..1.993 range while rpi uses 0..10 range.
This is a preparation patch without actually providing the control
itself, which is done in the following patch.
Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
Tested-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
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After black level handling has been moved to an algorithm module, white
balance and the construction of color tables can be moved to algorithm
modules too.
This time, the moved code is split between stats processing and
parameter construction methods. It is also split to two algorithm
modules:
- White balance computation.
- Gamma table computation and color lookup tables construction. While
this applies the color gains computed by the white balance algorithm,
it is not directly related to white balance. And we may want to
modify the color lookup tables in future according to other parameters
than just gamma and white balance gains.
Gamma table computation and color lookup tables construction could be
split to separate algorithms too. But there is no big need for that now
so they are kept together for simplicity.
This is the only part of the software ISP algorithms that sets the
parameters so emitting setIspParams can be moved to prepare() method.
A more natural representation of the gains (and black level) would be
floating point numbers. This is not done here in order to minimize
changes in code movements. It will be addressed in a followup patch.
Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Acked-by: Umang Jain <umang.jain@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
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