Capturing images using libcamera in Microchip platforms
Introduction
libcamera is an open-source software library handling image signal processors and embedded cameras that is supported on Linux based distributions. Refer libcamera architecture to know more about the architecture
Here is a block diagram from the official libcamera page
--------------------------< libcamera Public API >---------------------------
^ ^
| |
v v
+-------------+ +---------------------------------------------------+
| Camera | | Camera Device |
| Manager | | +-----------------------------------------------+ |
+-------------+ | | Device-Agnostic | |
^ | | | |
| | | +--------------------------+ |
| | | | ~~~~~~~~~~~~~~~~~~~~~~~ |
| | | | { +-----------------+ } |
| | | | } | //// Image //// | { |
| | | | <-> | / Processing // | } |
| | | | } | / Algorithms // | { |
| | | | { +-----------------+ } |
| | | | ~~~~~~~~~~~~~~~~~~~~~~~ |
| | | | ========================== |
| | | | +-----------------+ |
| | | | | // Pipeline /// | |
| | | | <-> | /// Handler /// | |
| | | | | /////////////// | |
| | +--------------------+ +-----------------+ |
| | Device-Specific |
| +---------------------------------------------------+
| ^ ^
| | |
v v v
+--------------------------------------------------------------------+
| Helpers and Support Classes |
| +-------------+ +-------------+ +-------------+ +-------------+ |
| | MC & V4L2 | | Buffers | | Sandboxing | | Plugins | |
| | Support | | Allocator | | IPC | | Manager | |
| +-------------+ +-------------+ +-------------+ +-------------+ |
| +-------------+ +-------------+ |
| | Pipeline | | ... | |
| | Runner | | | |
| +-------------+ +-------------+ |
+--------------------------------------------------------------------+
/// Device-Specific Components
~~~ Sandboxing
Traditionally the camera interfaces in linux4sam platforms are configured using media-ctl and v4l2-ctl commands. Each entities in the pipeline has to be configured separately. Libcamera provides a higher level, flexible interface to manage this complexity.
It abstracts away the hardware differences and provides a consistent interface making it easier for application developers to support multiple devices. It provides control over camera pipelines, including white balance, gain and sensor tuning which is very critical for high quality image capture.
Microchip specific pipeline handler
In libcamera, a pipeline handler is a core component responsible for interfacing with camera hardware. It manages the media devices, configures the camera pipeline, and handles image capture operations. Each hardware platform typically requires a specific pipeline handler to accommodate its unique architecture and capabilities.The pipeline handler is a component of libcamera that is device specific. It manages the complex pipelines exposed by the kernel drivers through the Media Controller and V4L2 APIs. You can find the supported devices in the libcamera source in the following path src/libcamera/pipeline. The microchip ISC pipeline handler is implemented here
Capturing images using mchpcam-still
mchpcam-still is a comprehensive userspace demo application that can configure the microchip ISC and capture images. The application supports various image processing options and algorithms that are explained below with few examples.
Features in mchpcam-still
root@sama7g5ek-sd:~# mchpcam-still -h
Usage: mchpcam-still [options]
Camera options:
-c, --camera=CAMERA Camera index or name
-o, --output=FILE Output file name (default: output.jpg)
-f, --format=FORMAT Set pixel format (YUYV, RGB565)
--width=WIDTH Set capture width
--height=HEIGHT Set capture height
Image options:
--jpeg-quality=VALUE Set JPEG quality (1-100, default: 95)
--png-compression=VALUE Set PNG compression level (0-9, default: 6)
--raw Save raw sensor data instead of processed image
--image-format=FORMAT Set output image format (jpeg, png, raw)
Image processing options:
--brightness=VALUE Set brightness (-100 to 100)
--contrast=VALUE Set contrast (0 to 100)
--gamma=VALUE Set gamma (0 to 2)
--enable-processing Enable software image processing
White balance options:
--awb=MODE Set white balance mode (auto, daylight, cloudy, tungsten, fluorescent, shade, manual)
--awb-enable Enable auto white balance
--red-gain=VALUE Set red component gain (0 to 8191)
--blue-gain=VALUE Set blue component gain (0 to 8191)
--green-red-gain=VALUE Set green-red component gain (0 to 8191)
--green-blue-gain=VALUE Set green-blue component gain (0 to 8191)
--red-offset=VALUE Set red component offset (-4095 to 4095)
--blue-offset=VALUE Set blue component offset (-4095 to 4095)
--green-red-offset=VALUE Set green-red component offset (-4095 to 4095)
--green-blue-offset=VALUE Set green-blue component offset (-4095 to 4095)
Algorithm options:
--enable-agc Enable Automatic Gain Control
--enable-blc Enable Black Level Correction
--enable-ccm Enable Color Correction Matrix
--enable-awb Enable Software Auto white balance processing
--enable-all Enable all image processing algorithms
General options:
-h, --help Print this help message
Examples
Capture a basic JPEG image with default settings at 1920x1080 resolution. The image is stored as output.jpg
root@sama7g5ek-sd:~# mchpcam-still
Requested resolution: 1920x1080
[0:14:40.401418600] [278] INFO Camera camera_manager.cpp:313 libcamera v0.0.0+4886-linux4microchip-2025.04-rc1-dirty (2025-04-29T11:52:14UTC)
[0:14:40.487015400] [279] WARN CameraSensor camera_sensor.cpp:259 'imx219 1-0010': Recommended V4L2 control 0x009a0922 not supported
[0:14:40.487442400] [279] WARN CameraSensor camera_sensor.cpp:331 'imx219 1-0010': The sensor kernel driver needs to be fixed
[0:14:40.487654000] [279] WARN CameraSensor camera_sensor.cpp:333 'imx219 1-0010': See Documentation/sensor_driver_requirements.rst in the libcamera sources forn
[0:14:40.494302600] [279] WARN CameraSensor camera_sensor.cpp:479 'imx219 1-0010': Failed to retrieve the camera location
[0:14:40.494579000] [279] WARN CameraSensor camera_sensor.cpp:501 'imx219 1-0010': Rotation control not available, default to 0 degrees
[0:14:40.500917800] [279] WARN V4L2 v4l2_pixelformat.cpp:344 Unsupported V4L2 pixel format AR12
[0:14:40.501554000] [279] WARN V4L2 v4l2_pixelformat.cpp:344 Unsupported V4L2 pixel format AR15
[0:14:40.503753200] [279] WARN V4L2 v4l2_pixelformat.cpp:344 Unsupported V4L2 pixel format AR12
[0:14:40.504289200] [279] WARN V4L2 v4l2_pixelformat.cpp:344 Unsupported V4L2 pixel format AR15
[0:14:40.506403400] [279] WARN V4L2 v4l2_pixelformat.cpp:344 Unsupported V4L2 pixel format AR12
[0:14:40.506860400] [279] WARN V4L2 v4l2_pixelformat.cpp:344 Unsupported V4L2 pixel format AR15
[0:14:40.509049000] [279] WARN V4L2 v4l2_pixelformat.cpp:344 Unsupported V4L2 pixel format AR12
[0:14:40.509498400] [279] WARN V4L2 v4l2_pixelformat.cpp:344 Unsupported V4L2 pixel format AR15
[0:14:40.511733400] [279] WARN V4L2 v4l2_pixelformat.cpp:344 Unsupported V4L2 pixel format AR12
[0:14:40.512180600] [279] WARN V4L2 v4l2_pixelformat.cpp:344 Unsupported V4L2 pixel format AR15
[0:14:40.514252600] [279] WARN V4L2 v4l2_pixelformat.cpp:344 Unsupported V4L2 pixel format AR12
[0:14:40.514784200] [279] WARN V4L2 v4l2_pixelformat.cpp:344 Unsupported V4L2 pixel format AR15
[0:14:40.516905400] [279] WARN V4L2 v4l2_pixelformat.cpp:344 Unsupported V4L2 pixel format AR12
[0:14:40.517358200] [279] WARN V4L2 v4l2_pixelformat.cpp:344 Unsupported V4L2 pixel format AR15
[0:14:40.519463600] [279] WARN V4L2 v4l2_pixelformat.cpp:344 Unsupported V4L2 pixel format AR12
[0:14:40.519906800] [279] WARN V4L2 v4l2_pixelformat.cpp:344 Unsupported V4L2 pixel format AR15
[0:14:40.522508800] [279] INFO MicrochipISC microchip-isc.cpp:401 Registered camera '/base/soc/flexcom@e2818000/i2c@600/camera@10'
[0:14:40.524360800] [278] INFO Camera camera.cpp:1183 configuring streams: (0) 1920x1080-RGB565
Camera configured with format: RGB565 (1920x1080)
Applying Default AWB parameters :
Red Gain: 1944
Blue Gain: 3404
Green-Red Gain: 1103
Green-Blue Gain: 1619
Red Offset: 7928
Blue Offset: 7936
Green-Red Offset: 7920
Green-Blue Offset: 7920
Configured for capture: 1920x1080 format: RGB565
Applying Default AWB parameters :
Red Gain: 1944
Blue Gain: 3404
Green-Red Gain: 1103
Green-Blue Gain: 1619
Red Offset: 7928
Blue Offset: 7936
Green-Red Offset: 7920
Green-Blue Offset: 7920
Capturing image...
[drivers/media/platform/microchip/microchip-sama7g5-isc.c:isc_sama7g5_config_dpc:301] bay_cfg = 0x1
[drivers/media/platform/microchip/microchip-sama7g5-isc.c:isc_sama7g5_config_dpc:321] ISC_DPC_CFG = 0x40006011
Sequence: 000000 timestamp: 880966700000
[0:14:41.243092200] [279] WARN ISC_IPA microchip_isc_ipa.cpp:114 Unknown format 0x300f, defaulting to Raw Bayer processing
Captured image with resolution: 1920x1080
Saved JPEG image to output.jpg with quality 95
Capture image with IPA software processing for default settings. This enables awb=auto,agc,ccm by default
root@sama7g5ek-sd:~# mchpcam-still --enable-processing
Capture a high-quality image with specific resolution:
root@sama7g5ek-sd:~# mchpcam-still --width=1920 --height=1080 --jpeg-quality=100 -o high_quality.jpg
Capture with specific white balance mode:
root@sama7g5ek-sd:~# mchpcam-still --awb=daylight -o daylight_scene.jpg
Enable all software processing:
root@sama7g5ek-sd:~# mchpcam-still --enable-processing --enable-all -o processed.jpg
Capture with custom white balance settings:
root@sama7g5ek-sd:~# mchpcam-still --awb=manual --red-gain=2000 --blue-gain=3500 -o custom_wb.jpg
Capture at 640x480 resolution with YUV format:
root@sama7g5ek-sd:~# mchpcam-still --width=640 --height=480 --format=YUYV -o small.jpg
