Pass contrastExp as calculated in lut to debayer params not the raw
contrast. This way we calculate contrastExp once per frame in lut and pass
the calculated value into the shaders, instead of passing contrast and
calculating contrastExp once per pixel in the shaders.
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Reviewed-by: Milan Zamazal <mzamazal@redhat.com>
Tested-by: Robert Mader <robert.mader@collabora.com>
Tested-by: Hans de Goede <johannes.goede@oss.qualcomm.com> # ThinkPad T14s gen 6 (arm64) ov02c10 + X1c gen 12 ov08x40
Tested-by: Kieran Bingham <kieran.bingham@ideasonboard.com> # Lenovo X13s
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Software CPU ISP computes a gamma lookup table. The table incorporates
black level and contrast. All entries in the table below the black
level are set to 0. This is not necessarily correct all the time.
Let's consider this case: The CCM is
[1 0 0]
[0 1 0]
[0 0 0]
and contrast is set to zero. The gamma table has all the entries above
the black level set to 186 (due to zero contrast) and all the entries
below the black level set to 0. CCM is applied before gamma, a
non-black level pixel has the blue component set to 0 with the CCM
above. Now, when the gamma lookup is applied, the red and green
components are set to 186, while the blue component is set to 0. The
resulting pixel is then yellow rather than grey (as it should be with
zero contrast).
There are two ways to fix this: Either clamping pixel colour channels to
the black level in debayering or setting the below black level entries
in the gamma lookup table to the lowest value of the gamma table rather
than 0. Both should have the same effect. Let's opt for the latter for
its simplicity.
Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
Reviewed-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
A colour correction matrix (CCM) is applied like this to an RGB pixel
vector P:
CCM * P
White balance must be applied before CCM. If CCM is used, software ISP
makes a combined matrix by multiplying the CCM by a white balance gains
CCM-like matrix (WBG). The multiplication should be as follows to do it
in the correct order:
CCM * (WBG * P) = (CCM * WBG) * P
The multiplication order in Lut software ISP algorithm is reversed,
resulting in colour casts. Let's fix the order.
Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Tested-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
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>
This patch adds color correction matrix (CCM) algorithm to software ISP.
It is based on the corresponding algorithm in rkisp1.
The primary difference against hardware pipelines is that applying the
CCM is optional. Applying CCM causes a significant slowdown, time
needed to process a frame raises by 40-90% on tested platforms. If CCM
is really needed, it can be applied, if not, it's better to stick
without it. This can be configured by presence or omission of Ccm
algorithm in the tuning file.
CCM is changed only if the determined temperature changes by at least
100 K (an arbitrarily selected value), to avoid recomputing the matrices
and lookup tables all the time.
Since the CCM is float, rather than double, to use the same type as in
the rkisp1 pipeline, the type of color gains is changed from double to
float.
The outputs of the algorithm are not used yet, they will be enabled in
followup patches.
Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
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: Kieran Bingham <kieran.bingham@ideasonboard.com>
The AWB algorithm has data to determine color temperature of the image.
Let's compute the temperature from it and store it into the context.
This piece of information is currently unused but it will be needed in a
followup patch introducing support for color correction matrix.
Let's store the white balance related information under `awb' subsection
of the active state, as the hardware pipelines do.
Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
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: Kieran Bingham <kieran.bingham@ideasonboard.com>
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>
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>
It's more natural to represent color gains as floating point numbers
rather than using a particular pixel-related representation.
double is used rather than float because it's a more common floating
point type in libcamera algorithms. Otherwise there is no obvious
reason to select one over the other here.
The constructed color tables still use integer representation for
efficiency.
Black level still uses pixel (integer) values, for consistency with
other libcamera parts.
Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
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>
Bryan O'Donoghue
Milan Zamazal
Barnabás Pőcze