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The relative luminance is calculated using an iterative process to
account for saturation in the sensor, as multiplying pixels by a gain
doesn't increase the relative luminance by the same factor if some
regions are saturated. Relative luminance estimation doesn't apply a
saturation, which produces a value that doesn't match what the sensor
will output, and defeats the point of the iterative process. Fix it.
Fixes: f8f07f9468c6 ("ipa: ipu3: agc: Improve gain calculation")
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Tested-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
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The inter-quantile mean is a value that is computed as part of the AGC
run. It doesn't need to be stored in a member variable. Return it from
measureBrightness(), which makes the flow of data easier to follow.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
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The "current" prefix in the currentYGain variable name is confusing:
- In Agc::estimateLuminance(), the variable contains the gain to be
applied to the image, which is neither a "current" gain nor a "Y"
gain. Rename it to "gain".
- In Agc::computeExposure(), the variable contains the gain computed by
the relative luminance method, so rename it to "yGain".
While at it, rename variables to match the libcamera coding style.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
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The AGC computes the average relative luminance of the frame and calls
the value "normalized luma", "brightness" or "initialY". The latter is
the most accurate term, as the relative luminance is abbreviated Y, but
the "initial" prefix isn't accurate.
Standardize the vocabulary on "relative luminance" in code and comments,
abbreviating it to Y when needed.
While at it, rename variables to match the libcamera coding style.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
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The kMaxLuminance constant is badly named, it's not a maximum luminance,
but the maximum integer value output by the AWB statistics engine for
per-channel averages. The constant is used in a single place, hardcoding
the value is actually more readable.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
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Until commit f8f07f9468c6 (ipa: ipu3: agc: Improve gain calculation)
the gain to apply on the exposure value was only using the histogram.
Now that the global brightness of the frame is estimated too, we don't
need to remove part of the saturated pixels from the equation anymore.
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
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The minimum and maximum exposure are stored in lines. Replace it by
values in time to simplify the calculations.
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
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Previously, the exposure value was calculated based on the estimated
shutter time and gain applied. Now that we have the real values for the
current frame, use those before estimating the next one and rename the
variable accordingly.
As the exposure value is updated in the beginning of the computation,
there is no need to initialize effectiveExposureValue anymore in the
configure call, and it can be a local variable and not a class variable
anymore.
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
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When an image is partially saturated, its brightness is not increasing
linearly when the shutter time or gain increases. It is a big issue with
a backlight as the algorithm is fading to darkness right now.
Introduce a function to estimate the brightness of the frame, based on
the current exposure/gain and loop on it several times to estimate it
again and approach the non linear function.
Inspired-by: 7de5506c30b3 ("libcamera: src: ipa: raspberrypi: agc: Improve gain update calculation for partly saturated images")
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>
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When we compute the new gain, we use the iqMean_ and estimate an
exposure value gain to apply. Return early when the gain is less than
1%.
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
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Now that we have the real exposure applied at each frame, remove the
early return based on a frame counter and compute the gain for each
frame.
Introduce a number of startup frames during which the filter speed is
1.0, meaning we apply instantly the exposure value calculated and not a
slower filtered one. This is used to have a faster convergence, and
those frames may be dropped in a future development to hide the
convergance process from the viewer.
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
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When the histogram is calculated, we check if a cell is saturated or not
before cumulating its green value. This is wrong, and it can lead to an
empty histogram in case of a fully saturated frame.
Use a constant to limit the amount of pixels within a cell before
considering it saturated. If at the end of the loop we still have an
empty histogram, then make it a fully saturated one.
Bug: https://bugs.libcamera.org/show_bug.cgi?id=84
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
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The pipeline handler populates the new sensorControls ControlList, to
have the effective exposure and gain values for the current frame. This
is done when a statistics buffer is received.
Make those values the frameContext::sensor values for the frame when the
EventStatReady event is received.
AGC also needs to use frameContext.sensor as its input values and
frameContext.agc as its output values. Modify computeExposure by passing
it the frameContext instead of individual exposure and gain values.
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
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In case the maximum exposure received from the sensor is very high, we
can have a very high shutter speed with a small analogue gain, and it
may result in very slow framerate. We are not really supporting it for
the moment, so clamp the shutter speed to an arbitrary value of 60ms.
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Tested-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
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The AGC class was not documented while developing. Extend that to
reference the origins of the implementation, and improve the
descriptions on how the algorithm operates internally.
While at it, rename the functions which have bad names.
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
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Instead of using constants for the analogue gains limits, use the
minimum and maximum from the configured sensor.
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
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We currently control the exposure value by the shutter speed and the
analogue gain. We can't use the digital gain to have more than the
maximum exposure value calculated because we are not controlling it.
Remove unused code associated with this digital gain.
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
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Simplify the reading by removing one level of indentation to return
early when the change is small between two calls.
Reword the LOG() message when we are correctly exposed, and move the
lastFrame_ variable to update it even if the change is small.
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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We need to calculate the gain on the previous exposure value calculated.
Now that we initialise the exposure and gain values in configure(), we
know the initial exposure value, and we can set it before any loop is
running.
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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We have mixed terms between gain, analogue gain and the exposure value
gain.
Make it clear when we are using the analogue gain from the sensor, and
when we are using the calculated gain to be applied to the exposure
value to reach the target.
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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Until now, the algorithm makes complex assumptions when dividing the
exposure and analogue gain values. Instead, use a simpler clamping of
the shutter speed first, and then of the analogue gain, based on the
limits configured.
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
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We are filtering the exposure value to limit the gain to apply, but we
are not using the result.
Fix it.
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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The gains are currently set as a uint32_t while the analogue gain is
passed as a double. We also have a default maximum analogue gain of 15
which is quite high for a number of sensors.
Use a maximum value of 8 which should really be configured by the IPA
and not fixed as it is now. While at it make it a double.
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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We are using arbitrary constants for the exposure limit in a number of
lines.
Instead of using static constants for those, use the limits of the
sensor passed in IPASessionConfiguration and cache those.
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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The exposure value is filtered in filterExposure() using the
currentExposure_ and setting a prevExposure_ variable. This is misnamed
as it is not the previous exposure, but a filtered value.
Rename it accordingly.
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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The AGC frame context needs to be initialised correctly for the first
iteration. Until now, the IPA uses the minimum exposure and gain values
and caches those in local variables.
In order to give the sensor limits to AGC, create a new structure in
IPASessionConfiguration. Store the exposure in time (and not line
duration) and the analogue gain after CameraSensorHelper conversion.
Set the gain and exposure appropriately to the current values known to
the IPA and remove the setting of exposure and gain in IPAIPU3 as those
are now fully controlled by IPU3Agc.
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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"using" directives are harmful in headers, as they propagate the
namespace short-circuit to all files that include the header, directly
or indirectly. Drop the directive from agc.h, and use utils::Duration
explicitly. While at it, shorten the namespace qualifier from
libcamera::utils:: to utils:: in agc.cpp for Duration.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
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The intel-ipu3.h public interface from the kernel does not define how to
parse the statistics for a cell. This had to be identified by a process
of reverse engineering, and later identifying the structures from [0]
leading to our custom definition of struct Ipu3AwbCell.
[0]
https://chromium.googlesource.com/chromiumos/platform/arc-camera/+/refs/heads/master/hal/intel/include/ia_imaging/awb_public.h
To improve the kernel interface, a proposal has been made to the
linux-kernel [1] to incorporate the memory layout for each cell into the
intel-ipu3 header directly.
[1]
https://lore.kernel.org/linux-media/20211005202019.253353-1-jeanmichel.hautbois@ideasonboard.com/
Update our local copy of the intel-ipu3.h to match the proposal and
change the AGC and AWB algorithms to reference that structure directly,
allowing us to remove the deprecated custom Ipu3AwbCell definition.
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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Now that we know how the AWB statistics are formatted, use a simplified
loop in processBrightness() to parse the green values and get the
histogram.
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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The IPASessionConfiguration now has the grid configuration stored. Use
it at process() call in AGC and pass it as a reference to the private
functions when needed.
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
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Now that the interface is properly used by the AGC class, move it into
ipa::ipu3::algorithms and let the loops do the calls.
As we need to exchange the exposure_ and gain_ by passing them through the
FrameContext, use the calculated values in setControls() function to
ease the reading.
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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