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The black level determination, already present as a separate class, can
be moved to the prepared Algorithm processing structure. It is the
first of the current software ISP algorithms that is called in the stats
processing sequence, which means it is also the first one that should be
moved to the new structure. Stats processing starts with calling
Algorithm-based processing so the call order of the algorithms is
retained.
Movement of this algorithm is relatively straightforward because all it
does is processing stats.
The comment about getting black level from the tuning files is dropped.
The black level will be taken from CameraSensorHelper if available and
that will be implemented in one of the followup patches.
Black level is now recomputed on each stats processing. In a future
patch, after DelayedControls are used, this will be changed to recompute
the black level only after exposure/gain changes.
The black level depends on the sensor used, the computed value can be
reused in a followup capture sessions with the same sensor. Thus it is
sufficient to (re)set the initial value in BlackLevel::init.
Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
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IPA modules use custom namespaces for all their internal components to
avoid namespace clashes. The simple IPA module for the software ISP uses
libcamera::ipa::soft for this purpose. It however defines an internal
class named BlackLevel in the root of the libcamera namespace, making it
prone to clashes. Move it to the ipa::soft namespace along with the rest
of the code.
Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
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The documented range of values corresponds to uint8_t, so let's use that
type.
Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Andrei Konovalov <andrey.konovalov.ynk@gmail.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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Source files in libcamera start by a comment block header, which
includes the file name and a one-line description of the file contents.
While the latter is useful to get a quick overview of the file contents
at a glance, the former is mostly a source of inconvenience. The name in
the comments can easily get out of sync with the file name when files
are renamed, and copy & paste during development have often lead to
incorrect names being used to start with.
Readers of the source code are expected to know which file they're
looking it. Drop the file name from the header comment block.
The change was generated with the following script:
----------------------------------------
dirs="include/libcamera src test utils"
declare -rA patterns=(
['c']=' \* '
['cpp']=' \* '
['h']=' \* '
['py']='# '
['sh']='# '
)
for ext in ${!patterns[@]} ; do
files=$(for dir in $dirs ; do find $dir -name "*.${ext}" ; done)
pattern=${patterns[${ext}]}
for file in $files ; do
name=$(basename ${file})
sed -i "s/^\(${pattern}\)${name} - /\1/" "$file"
done
done
----------------------------------------
This misses several files that are out of sync with the comment block
header. Those will be addressed separately and manually.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
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Black may not be represented as 0 pixel value for given hardware, it may
be higher. If this is not compensated then various problems may occur
such as low contrast or suboptimal exposure.
The black pixel value can be either retrieved from a tuning file for the
given hardware, or automatically on the fly. The former is the right
and correct method, while the latter can be used when a tuning file is
not available for the given hardware. Since there is currently no
support for tuning files in software ISP, the automatic, hardware
independent way, is always used. Support for tuning files should be
added in future but it will require more work than this patch.
The patch looks at the image histogram and assumes that black starts
when pixel values start occurring on the left. A certain amount of the
darkest pixels is ignored; it doesn't matter whether they represent
various kinds of noise or are real, they are better to omit in any case
to make the image looking better. It also doesn't matter whether the
darkest pixels occur around the supposed black level or are spread
between 0 and the black level, the difference is not important.
An arbitrary threshold of 2% darkest pixels is applied; there is no
magic about that value.
The patch assumes that the black values for different colors are the
same and doesn't attempt any other non-primitive enhancements. It
cannot completely replace tuning files and simplicity, while providing
visible benefit, is its goal. Anything more sophisticated is left for
future patches.
A possible cheap enhancement, if needed, could be setting exposure +
gain to minimum values temporarily, before setting the black level. In
theory, the black level should be fixed but it may not be reached in all
images. For this reason, the patch updates black level only if the
observed value is lower than the current one; it should be never
increased.
The purpose of the patch is to compensate for hardware properties.
General image contrast enhancements are out of scope of this patch.
Stats are still gathered as an uncorrected histogram, to avoid any
confusion and to represent the raw image data. Exposure must be
determined after the black level correction -- it has no influence on
the sub-black area and must be correct after applying the black level
correction. The granularity of the histogram is increased from 16 to 64
to provide a better precision (there is no theory behind either of those
numbers).
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
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