592 строки
22 KiB
ReStructuredText
592 строки
22 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
|
|
|
|
.. include:: <isonum.txt>
|
|
|
|
===============================================================
|
|
Intel Image Processing Unit 3 (IPU3) Imaging Unit (ImgU) driver
|
|
===============================================================
|
|
|
|
Copyright |copy| 2018 Intel Corporation
|
|
|
|
Introduction
|
|
============
|
|
|
|
This file documents the Intel IPU3 (3rd generation Image Processing Unit)
|
|
Imaging Unit drivers located under drivers/media/pci/intel/ipu3 (CIO2) as well
|
|
as under drivers/staging/media/ipu3 (ImgU).
|
|
|
|
The Intel IPU3 found in certain Kaby Lake (as well as certain Sky Lake)
|
|
platforms (U/Y processor lines) is made up of two parts namely the Imaging Unit
|
|
(ImgU) and the CIO2 device (MIPI CSI2 receiver).
|
|
|
|
The CIO2 device receives the raw Bayer data from the sensors and outputs the
|
|
frames in a format that is specific to the IPU3 (for consumption by the IPU3
|
|
ImgU). The CIO2 driver is available as drivers/media/pci/intel/ipu3/ipu3-cio2*
|
|
and is enabled through the CONFIG_VIDEO_IPU3_CIO2 config option.
|
|
|
|
The Imaging Unit (ImgU) is responsible for processing images captured
|
|
by the IPU3 CIO2 device. The ImgU driver sources can be found under
|
|
drivers/staging/media/ipu3 directory. The driver is enabled through the
|
|
CONFIG_VIDEO_IPU3_IMGU config option.
|
|
|
|
The two driver modules are named ipu3_csi2 and ipu3_imgu, respectively.
|
|
|
|
The drivers has been tested on Kaby Lake platforms (U/Y processor lines).
|
|
|
|
Both of the drivers implement V4L2, Media Controller and V4L2 sub-device
|
|
interfaces. The IPU3 CIO2 driver supports camera sensors connected to the CIO2
|
|
MIPI CSI-2 interfaces through V4L2 sub-device sensor drivers.
|
|
|
|
CIO2
|
|
====
|
|
|
|
The CIO2 is represented as a single V4L2 subdev, which provides a V4L2 subdev
|
|
interface to the user space. There is a video node for each CSI-2 receiver,
|
|
with a single media controller interface for the entire device.
|
|
|
|
The CIO2 contains four independent capture channel, each with its own MIPI CSI-2
|
|
receiver and DMA engine. Each channel is modelled as a V4L2 sub-device exposed
|
|
to userspace as a V4L2 sub-device node and has two pads:
|
|
|
|
.. tabularcolumns:: |p{0.8cm}|p{4.0cm}|p{4.0cm}|
|
|
|
|
.. flat-table::
|
|
|
|
* - pad
|
|
- direction
|
|
- purpose
|
|
|
|
* - 0
|
|
- sink
|
|
- MIPI CSI-2 input, connected to the sensor subdev
|
|
|
|
* - 1
|
|
- source
|
|
- Raw video capture, connected to the V4L2 video interface
|
|
|
|
The V4L2 video interfaces model the DMA engines. They are exposed to userspace
|
|
as V4L2 video device nodes.
|
|
|
|
Capturing frames in raw Bayer format
|
|
------------------------------------
|
|
|
|
CIO2 MIPI CSI2 receiver is used to capture frames (in packed raw Bayer format)
|
|
from the raw sensors connected to the CSI2 ports. The captured frames are used
|
|
as input to the ImgU driver.
|
|
|
|
Image processing using IPU3 ImgU requires tools such as raw2pnm [#f1]_, and
|
|
yavta [#f2]_ due to the following unique requirements and / or features specific
|
|
to IPU3.
|
|
|
|
-- The IPU3 CSI2 receiver outputs the captured frames from the sensor in packed
|
|
raw Bayer format that is specific to IPU3.
|
|
|
|
-- Multiple video nodes have to be operated simultaneously.
|
|
|
|
Let us take the example of ov5670 sensor connected to CSI2 port 0, for a
|
|
2592x1944 image capture.
|
|
|
|
Using the media contorller APIs, the ov5670 sensor is configured to send
|
|
frames in packed raw Bayer format to IPU3 CSI2 receiver.
|
|
|
|
# This example assumes /dev/media0 as the CIO2 media device
|
|
|
|
export MDEV=/dev/media0
|
|
|
|
# and that ov5670 sensor is connected to i2c bus 10 with address 0x36
|
|
|
|
export SDEV=$(media-ctl -d $MDEV -e "ov5670 10-0036")
|
|
|
|
# Establish the link for the media devices using media-ctl [#f3]_
|
|
media-ctl -d $MDEV -l "ov5670:0 -> ipu3-csi2 0:0[1]"
|
|
|
|
# Set the format for the media devices
|
|
media-ctl -d $MDEV -V "ov5670:0 [fmt:SGRBG10/2592x1944]"
|
|
|
|
media-ctl -d $MDEV -V "ipu3-csi2 0:0 [fmt:SGRBG10/2592x1944]"
|
|
|
|
media-ctl -d $MDEV -V "ipu3-csi2 0:1 [fmt:SGRBG10/2592x1944]"
|
|
|
|
Once the media pipeline is configured, desired sensor specific settings
|
|
(such as exposure and gain settings) can be set, using the yavta tool.
|
|
|
|
e.g
|
|
|
|
yavta -w 0x009e0903 444 $SDEV
|
|
|
|
yavta -w 0x009e0913 1024 $SDEV
|
|
|
|
yavta -w 0x009e0911 2046 $SDEV
|
|
|
|
Once the desired sensor settings are set, frame captures can be done as below.
|
|
|
|
e.g
|
|
|
|
yavta --data-prefix -u -c10 -n5 -I -s2592x1944 --file=/tmp/frame-#.bin \
|
|
-f IPU3_SGRBG10 $(media-ctl -d $MDEV -e "ipu3-cio2 0")
|
|
|
|
With the above command, 10 frames are captured at 2592x1944 resolution, with
|
|
sGRBG10 format and output as IPU3_SGRBG10 format.
|
|
|
|
The captured frames are available as /tmp/frame-#.bin files.
|
|
|
|
ImgU
|
|
====
|
|
|
|
The ImgU is represented as two V4L2 subdevs, each of which provides a V4L2
|
|
subdev interface to the user space.
|
|
|
|
Each V4L2 subdev represents a pipe, which can support a maximum of 2 streams.
|
|
This helps to support advanced camera features like Continuous View Finder (CVF)
|
|
and Snapshot During Video(SDV).
|
|
|
|
The ImgU contains two independent pipes, each modelled as a V4L2 sub-device
|
|
exposed to userspace as a V4L2 sub-device node.
|
|
|
|
Each pipe has two sink pads and three source pads for the following purpose:
|
|
|
|
.. tabularcolumns:: |p{0.8cm}|p{4.0cm}|p{4.0cm}|
|
|
|
|
.. flat-table::
|
|
|
|
* - pad
|
|
- direction
|
|
- purpose
|
|
|
|
* - 0
|
|
- sink
|
|
- Input raw video stream
|
|
|
|
* - 1
|
|
- sink
|
|
- Processing parameters
|
|
|
|
* - 2
|
|
- source
|
|
- Output processed video stream
|
|
|
|
* - 3
|
|
- source
|
|
- Output viewfinder video stream
|
|
|
|
* - 4
|
|
- source
|
|
- 3A statistics
|
|
|
|
Each pad is connected to a corresponding V4L2 video interface, exposed to
|
|
userspace as a V4L2 video device node.
|
|
|
|
Device operation
|
|
----------------
|
|
|
|
With ImgU, once the input video node ("ipu3-imgu 0/1":0, in
|
|
<entity>:<pad-number> format) is queued with buffer (in packed raw Bayer
|
|
format), ImgU starts processing the buffer and produces the video output in YUV
|
|
format and statistics output on respective output nodes. The driver is expected
|
|
to have buffers ready for all of parameter, output and statistics nodes, when
|
|
input video node is queued with buffer.
|
|
|
|
At a minimum, all of input, main output, 3A statistics and viewfinder
|
|
video nodes should be enabled for IPU3 to start image processing.
|
|
|
|
Each ImgU V4L2 subdev has the following set of video nodes.
|
|
|
|
input, output and viewfinder video nodes
|
|
----------------------------------------
|
|
|
|
The frames (in packed raw Bayer format specific to the IPU3) received by the
|
|
input video node is processed by the IPU3 Imaging Unit and are output to 2 video
|
|
nodes, with each targeting a different purpose (main output and viewfinder
|
|
output).
|
|
|
|
Details onand the Bayer format specific to the IPU3 can be found in
|
|
:ref:`v4l2-pix-fmt-ipu3-sbggr10`.
|
|
|
|
The driver supports V4L2 Video Capture Interface as defined at :ref:`devices`.
|
|
|
|
Only the multi-planar API is supported. More details can be found at
|
|
:ref:`planar-apis`.
|
|
|
|
Parameters video node
|
|
---------------------
|
|
|
|
The parameters video node receives the ImgU algorithm parameters that are used
|
|
to configure how the ImgU algorithms process the image.
|
|
|
|
Details on processing parameters specific to the IPU3 can be found in
|
|
:ref:`v4l2-meta-fmt-params`.
|
|
|
|
3A statistics video node
|
|
------------------------
|
|
|
|
3A statistics video node is used by the ImgU driver to output the 3A (auto
|
|
focus, auto exposure and auto white balance) statistics for the frames that are
|
|
being processed by the ImgU to user space applications. User space applications
|
|
can use this statistics data to compute the desired algorithm parameters for
|
|
the ImgU.
|
|
|
|
Configuring the Intel IPU3
|
|
==========================
|
|
|
|
The IPU3 ImgU pipelines can be configured using the Media Controller, defined at
|
|
:ref:`media_controller`.
|
|
|
|
Running mode and firmware binary selection
|
|
------------------------------------------
|
|
|
|
ImgU works based on firmware, currently the ImgU firmware support run 2 pipes in
|
|
time-sharing with single input frame data. Each pipe can run at certain mode -
|
|
"VIDEO" or "STILL", "VIDEO" mode is commonly used for video frames capture, and
|
|
"STILL" is used for still frame capture. However, you can also select "VIDEO" to
|
|
capture still frames if you want to capture images with less system load and
|
|
power. For "STILL" mode, ImgU will try to use smaller BDS factor and output
|
|
larger bayer frame for further YUV processing than "VIDEO" mode to get high
|
|
quality images. Besides, "STILL" mode need XNR3 to do noise reduction, hence
|
|
"STILL" mode will need more power and memory bandwidth than "VIDEO" mode. TNR
|
|
will be enabled in "VIDEO" mode and bypassed by "STILL" mode. ImgU is running at
|
|
“VIDEO” mode by default, the user can use v4l2 control V4L2_CID_INTEL_IPU3_MODE
|
|
(currently defined in drivers/staging/media/ipu3/include/intel-ipu3.h) to query
|
|
and set the running mode. For user, there is no difference for buffer queueing
|
|
between the "VIDEO" and "STILL" mode, mandatory input and main output node
|
|
should be enabled and buffers need be queued, the statistics and the view-finder
|
|
queues are optional.
|
|
|
|
The firmware binary will be selected according to current running mode, such log
|
|
"using binary if_to_osys_striped " or "using binary if_to_osys_primary_striped"
|
|
could be observed if you enable the ImgU dynamic debug, the binary
|
|
if_to_osys_striped is selected for "VIDEO" and the binary
|
|
"if_to_osys_primary_striped" is selected for "STILL".
|
|
|
|
|
|
Processing the image in raw Bayer format
|
|
----------------------------------------
|
|
|
|
Configuring ImgU V4L2 subdev for image processing
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
The ImgU V4L2 subdevs have to be configured with media controller APIs to have
|
|
all the video nodes setup correctly.
|
|
|
|
Let us take "ipu3-imgu 0" subdev as an example.
|
|
|
|
media-ctl -d $MDEV -r
|
|
|
|
media-ctl -d $MDEV -l "ipu3-imgu 0 input":0 -> "ipu3-imgu 0":0[1]
|
|
|
|
media-ctl -d $MDEV -l "ipu3-imgu 0":2 -> "ipu3-imgu 0 output":0[1]
|
|
|
|
media-ctl -d $MDEV -l "ipu3-imgu 0":3 -> "ipu3-imgu 0 viewfinder":0[1]
|
|
|
|
media-ctl -d $MDEV -l "ipu3-imgu 0":4 -> "ipu3-imgu 0 3a stat":0[1]
|
|
|
|
Also the pipe mode of the corresponding V4L2 subdev should be set as desired
|
|
(e.g 0 for video mode or 1 for still mode) through the control id 0x009819a1 as
|
|
below.
|
|
|
|
yavta -w "0x009819A1 1" /dev/v4l-subdev7
|
|
|
|
Certain hardware blocks in ImgU pipeline can change the frame resolution by
|
|
cropping or scaling, these hardware blocks include Input Feeder(IF), Bayer Down
|
|
Scaler (BDS) and Geometric Distortion Correction (GDC).
|
|
There is also a block which can change the frame resolution - YUV Scaler, it is
|
|
only applicable to the secondary output.
|
|
|
|
RAW Bayer frames go through these ImgU pipeline hardware blocks and the final
|
|
processed image output to the DDR memory.
|
|
|
|
.. kernel-figure:: ipu3_rcb.svg
|
|
:alt: ipu3 resolution blocks image
|
|
|
|
IPU3 resolution change hardware blocks
|
|
|
|
**Input Feeder**
|
|
|
|
Input Feeder gets the Bayer frame data from the sensor, it can enable cropping
|
|
of lines and columns from the frame and then store pixels into device's internal
|
|
pixel buffer which are ready to readout by following blocks.
|
|
|
|
**Bayer Down Scaler**
|
|
|
|
Bayer Down Scaler is capable of performing image scaling in Bayer domain, the
|
|
downscale factor can be configured from 1X to 1/4X in each axis with
|
|
configuration steps of 0.03125 (1/32).
|
|
|
|
**Geometric Distortion Correction**
|
|
|
|
Geometric Distortion Correction is used to performe correction of distortions
|
|
and image filtering. It needs some extra filter and envelop padding pixels to
|
|
work, so the input resolution of GDC should be larger than the output
|
|
resolution.
|
|
|
|
**YUV Scaler**
|
|
|
|
YUV Scaler which similar with BDS, but it is mainly do image down scaling in
|
|
YUV domain, it can support up to 1/12X down scaling, but it can not be applied
|
|
to the main output.
|
|
|
|
The ImgU V4L2 subdev has to be configured with the supported resolutions in all
|
|
the above hardware blocks, for a given input resolution.
|
|
For a given supported resolution for an input frame, the Input Feeder, Bayer
|
|
Down Scaler and GDC blocks should be configured with the supported resolutions
|
|
as each hardware block has its own alignment requirement.
|
|
|
|
You must configure the output resolution of the hardware blocks smartly to meet
|
|
the hardware requirement along with keeping the maximum field of view. The
|
|
intermediate resolutions can be generated by specific tool -
|
|
|
|
https://github.com/intel/intel-ipu3-pipecfg
|
|
|
|
This tool can be used to generate intermediate resolutions. More information can
|
|
be obtained by looking at the following IPU3 ImgU configuration table.
|
|
|
|
https://chromium.googlesource.com/chromiumos/overlays/board-overlays/+/master
|
|
|
|
Under baseboard-poppy/media-libs/cros-camera-hal-configs-poppy/files/gcss
|
|
directory, graph_settings_ov5670.xml can be used as an example.
|
|
|
|
The following steps prepare the ImgU pipeline for the image processing.
|
|
|
|
1. The ImgU V4L2 subdev data format should be set by using the
|
|
VIDIOC_SUBDEV_S_FMT on pad 0, using the GDC width and height obtained above.
|
|
|
|
2. The ImgU V4L2 subdev cropping should be set by using the
|
|
VIDIOC_SUBDEV_S_SELECTION on pad 0, with V4L2_SEL_TGT_CROP as the target,
|
|
using the input feeder height and width.
|
|
|
|
3. The ImgU V4L2 subdev composing should be set by using the
|
|
VIDIOC_SUBDEV_S_SELECTION on pad 0, with V4L2_SEL_TGT_COMPOSE as the target,
|
|
using the BDS height and width.
|
|
|
|
For the ov5670 example, for an input frame with a resolution of 2592x1944
|
|
(which is input to the ImgU subdev pad 0), the corresponding resolutions
|
|
for input feeder, BDS and GDC are 2592x1944, 2592x1944 and 2560x1920
|
|
respectively.
|
|
|
|
Once this is done, the received raw Bayer frames can be input to the ImgU
|
|
V4L2 subdev as below, using the open source application v4l2n [#f1]_.
|
|
|
|
For an image captured with 2592x1944 [#f4]_ resolution, with desired output
|
|
resolution as 2560x1920 and viewfinder resolution as 2560x1920, the following
|
|
v4l2n command can be used. This helps process the raw Bayer frames and produces
|
|
the desired results for the main output image and the viewfinder output, in NV12
|
|
format.
|
|
|
|
v4l2n --pipe=4 --load=/tmp/frame-#.bin --open=/dev/video4
|
|
--fmt=type:VIDEO_OUTPUT_MPLANE,width=2592,height=1944,pixelformat=0X47337069
|
|
--reqbufs=type:VIDEO_OUTPUT_MPLANE,count:1 --pipe=1 --output=/tmp/frames.out
|
|
--open=/dev/video5
|
|
--fmt=type:VIDEO_CAPTURE_MPLANE,width=2560,height=1920,pixelformat=NV12
|
|
--reqbufs=type:VIDEO_CAPTURE_MPLANE,count:1 --pipe=2 --output=/tmp/frames.vf
|
|
--open=/dev/video6
|
|
--fmt=type:VIDEO_CAPTURE_MPLANE,width=2560,height=1920,pixelformat=NV12
|
|
--reqbufs=type:VIDEO_CAPTURE_MPLANE,count:1 --pipe=3 --open=/dev/video7
|
|
--output=/tmp/frames.3A --fmt=type:META_CAPTURE,?
|
|
--reqbufs=count:1,type:META_CAPTURE --pipe=1,2,3,4 --stream=5
|
|
|
|
You can also use yavta [#f2]_ command to do same thing as above:
|
|
|
|
.. code-block:: none
|
|
|
|
yavta --data-prefix -Bcapture-mplane -c10 -n5 -I -s2592x1944 \
|
|
--file=frame-#.out-f NV12 /dev/video5 & \
|
|
yavta --data-prefix -Bcapture-mplane -c10 -n5 -I -s2592x1944 \
|
|
--file=frame-#.vf -f NV12 /dev/video6 & \
|
|
yavta --data-prefix -Bmeta-capture -c10 -n5 -I \
|
|
--file=frame-#.3a /dev/video7 & \
|
|
yavta --data-prefix -Boutput-mplane -c10 -n5 -I -s2592x1944 \
|
|
--file=/tmp/frame-in.cio2 -f IPU3_SGRBG10 /dev/video4
|
|
|
|
where /dev/video4, /dev/video5, /dev/video6 and /dev/video7 devices point to
|
|
input, output, viewfinder and 3A statistics video nodes respectively.
|
|
|
|
Converting the raw Bayer image into YUV domain
|
|
----------------------------------------------
|
|
|
|
The processed images after the above step, can be converted to YUV domain
|
|
as below.
|
|
|
|
Main output frames
|
|
~~~~~~~~~~~~~~~~~~
|
|
|
|
raw2pnm -x2560 -y1920 -fNV12 /tmp/frames.out /tmp/frames.out.ppm
|
|
|
|
where 2560x1920 is output resolution, NV12 is the video format, followed
|
|
by input frame and output PNM file.
|
|
|
|
Viewfinder output frames
|
|
~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
raw2pnm -x2560 -y1920 -fNV12 /tmp/frames.vf /tmp/frames.vf.ppm
|
|
|
|
where 2560x1920 is output resolution, NV12 is the video format, followed
|
|
by input frame and output PNM file.
|
|
|
|
Example user space code for IPU3
|
|
================================
|
|
|
|
User space code that configures and uses IPU3 is available here.
|
|
|
|
https://chromium.googlesource.com/chromiumos/platform/arc-camera/+/master/
|
|
|
|
The source can be located under hal/intel directory.
|
|
|
|
Overview of IPU3 pipeline
|
|
=========================
|
|
|
|
IPU3 pipeline has a number of image processing stages, each of which takes a
|
|
set of parameters as input. The major stages of pipelines are shown here:
|
|
|
|
.. kernel-render:: DOT
|
|
:alt: IPU3 ImgU Pipeline
|
|
:caption: IPU3 ImgU Pipeline Diagram
|
|
|
|
digraph "IPU3 ImgU" {
|
|
node [shape=box]
|
|
splines="ortho"
|
|
rankdir="LR"
|
|
|
|
a [label="Raw pixels"]
|
|
b [label="Bayer Downscaling"]
|
|
c [label="Optical Black Correction"]
|
|
d [label="Linearization"]
|
|
e [label="Lens Shading Correction"]
|
|
f [label="White Balance / Exposure / Focus Apply"]
|
|
g [label="Bayer Noise Reduction"]
|
|
h [label="ANR"]
|
|
i [label="Demosaicing"]
|
|
j [label="Color Correction Matrix"]
|
|
k [label="Gamma correction"]
|
|
l [label="Color Space Conversion"]
|
|
m [label="Chroma Down Scaling"]
|
|
n [label="Chromatic Noise Reduction"]
|
|
o [label="Total Color Correction"]
|
|
p [label="XNR3"]
|
|
q [label="TNR"]
|
|
r [label="DDR", style=filled, fillcolor=yellow, shape=cylinder]
|
|
s [label="YUV Downscaling"]
|
|
t [label="DDR", style=filled, fillcolor=yellow, shape=cylinder]
|
|
|
|
{ rank=same; a -> b -> c -> d -> e -> f -> g -> h -> i }
|
|
{ rank=same; j -> k -> l -> m -> n -> o -> p -> q -> s -> t}
|
|
|
|
a -> j [style=invis, weight=10]
|
|
i -> j
|
|
q -> r
|
|
}
|
|
|
|
The table below presents a description of the above algorithms.
|
|
|
|
======================== =======================================================
|
|
Name Description
|
|
======================== =======================================================
|
|
Optical Black Correction Optical Black Correction block subtracts a pre-defined
|
|
value from the respective pixel values to obtain better
|
|
image quality.
|
|
Defined in :c:type:`ipu3_uapi_obgrid_param`.
|
|
Linearization This algo block uses linearization parameters to
|
|
address non-linearity sensor effects. The Lookup table
|
|
table is defined in
|
|
:c:type:`ipu3_uapi_isp_lin_vmem_params`.
|
|
SHD Lens shading correction is used to correct spatial
|
|
non-uniformity of the pixel response due to optical
|
|
lens shading. This is done by applying a different gain
|
|
for each pixel. The gain, black level etc are
|
|
configured in :c:type:`ipu3_uapi_shd_config_static`.
|
|
BNR Bayer noise reduction block removes image noise by
|
|
applying a bilateral filter.
|
|
See :c:type:`ipu3_uapi_bnr_static_config` for details.
|
|
ANR Advanced Noise Reduction is a block based algorithm
|
|
that performs noise reduction in the Bayer domain. The
|
|
convolution matrix etc can be found in
|
|
:c:type:`ipu3_uapi_anr_config`.
|
|
DM Demosaicing converts raw sensor data in Bayer format
|
|
into RGB (Red, Green, Blue) presentation. Then add
|
|
outputs of estimation of Y channel for following stream
|
|
processing by Firmware. The struct is defined as
|
|
:c:type:`ipu3_uapi_dm_config`.
|
|
Color Correction Color Correction algo transforms sensor specific color
|
|
space to the standard "sRGB" color space. This is done
|
|
by applying 3x3 matrix defined in
|
|
:c:type:`ipu3_uapi_ccm_mat_config`.
|
|
Gamma correction Gamma correction :c:type:`ipu3_uapi_gamma_config` is a
|
|
basic non-linear tone mapping correction that is
|
|
applied per pixel for each pixel component.
|
|
CSC Color space conversion transforms each pixel from the
|
|
RGB primary presentation to YUV (Y: brightness,
|
|
UV: Luminance) presentation. This is done by applying
|
|
a 3x3 matrix defined in
|
|
:c:type:`ipu3_uapi_csc_mat_config`
|
|
CDS Chroma down sampling
|
|
After the CSC is performed, the Chroma Down Sampling
|
|
is applied for a UV plane down sampling by a factor
|
|
of 2 in each direction for YUV 4:2:0 using a 4x2
|
|
configurable filter :c:type:`ipu3_uapi_cds_params`.
|
|
CHNR Chroma noise reduction
|
|
This block processes only the chrominance pixels and
|
|
performs noise reduction by cleaning the high
|
|
frequency noise.
|
|
See struct :c:type:`ipu3_uapi_yuvp1_chnr_config`.
|
|
TCC Total color correction as defined in struct
|
|
:c:type:`ipu3_uapi_yuvp2_tcc_static_config`.
|
|
XNR3 eXtreme Noise Reduction V3 is the third revision of
|
|
noise reduction algorithm used to improve image
|
|
quality. This removes the low frequency noise in the
|
|
captured image. Two related structs are being defined,
|
|
:c:type:`ipu3_uapi_isp_xnr3_params` for ISP data memory
|
|
and :c:type:`ipu3_uapi_isp_xnr3_vmem_params` for vector
|
|
memory.
|
|
TNR Temporal Noise Reduction block compares successive
|
|
frames in time to remove anomalies / noise in pixel
|
|
values. :c:type:`ipu3_uapi_isp_tnr3_vmem_params` and
|
|
:c:type:`ipu3_uapi_isp_tnr3_params` are defined for ISP
|
|
vector and data memory respectively.
|
|
======================== =======================================================
|
|
|
|
Other often encountered acronyms not listed in above table:
|
|
|
|
ACC
|
|
Accelerator cluster
|
|
AWB_FR
|
|
Auto white balance filter response statistics
|
|
BDS
|
|
Bayer downscaler parameters
|
|
CCM
|
|
Color correction matrix coefficients
|
|
IEFd
|
|
Image enhancement filter directed
|
|
Obgrid
|
|
Optical black level compensation
|
|
OSYS
|
|
Output system configuration
|
|
ROI
|
|
Region of interest
|
|
YDS
|
|
Y down sampling
|
|
YTM
|
|
Y-tone mapping
|
|
|
|
A few stages of the pipeline will be executed by firmware running on the ISP
|
|
processor, while many others will use a set of fixed hardware blocks also
|
|
called accelerator cluster (ACC) to crunch pixel data and produce statistics.
|
|
|
|
ACC parameters of individual algorithms, as defined by
|
|
:c:type:`ipu3_uapi_acc_param`, can be chosen to be applied by the user
|
|
space through struct :c:type:`ipu3_uapi_flags` embedded in
|
|
:c:type:`ipu3_uapi_params` structure. For parameters that are configured as
|
|
not enabled by the user space, the corresponding structs are ignored by the
|
|
driver, in which case the existing configuration of the algorithm will be
|
|
preserved.
|
|
|
|
References
|
|
==========
|
|
|
|
.. [#f5] drivers/staging/media/ipu3/include/intel-ipu3.h
|
|
|
|
.. [#f1] https://github.com/intel/nvt
|
|
|
|
.. [#f2] http://git.ideasonboard.org/yavta.git
|
|
|
|
.. [#f3] http://git.ideasonboard.org/?p=media-ctl.git;a=summary
|
|
|
|
.. [#f4] ImgU limitation requires an additional 16x16 for all input resolutions
|