A Barcode reading plugin for EPICS Area Detector using OpenCV and Zbar libraries for barcode and QR code reading.
Primary Author: Jakub Wlodek, Corresponding Author: Kazimierz Gofron
The ADPluginBar plugin works with the EPICS control system and thus requires a supported version of EPICS base as well as synApps. synApps will include area detector and asyn, both required for ADPluginBar.
Two external libraries are required as well: OpenCV, which is used for image manipulation, and zbar which is an open source barcode detection library. Both can be built from source by cloning the respective repositories from github, or if on a debin/ubuntu system, slightly older versions can be downloaded using the package manager with the following commands:
sudo apt install libopencv-dev
sudo apt install libopencv-contrib-dev
sudo apt install libzbar-dev
In addition, the numbered versions of these packages may be needed. For example, on the debian 8 machine this was tested on, libopencv2.4 was used.
It is also possible to build both opencv and zbar from source, links to each github are placed in the github.io website linked at the top of this repository.
Once EPICS base, synApps, OpenCV, and zbar are all installed, some changes need to be made to the configuration files within area detector. First, enter into your areaDetector directory, and clone the ADPluginBar repository. It should be on the same level as ADCore.
Next, enter the ADCore directory, enter ADApp, and open the commonDriverMakefile file, and ensure that the following is added and uncommented after ADPluginEdge:
ifdef ADPLUGINBAR
$(DBD_NAME)_DBD += NDPluginBar.dbd
PROD_LIBS += NDPluginBar
ifdef OPENCV_LIB
opencv_core_DIR +=$(OPENCV_LIB)
PROD_LIBS += opencv_core opencv_imgproc opencv_highgui zbar
else
PROD_SYS_LIBS += opencv_core opencv_imgproc opencv_highgui zbar
endif
endif
This will link the necessary OpenCV and zbar libraries when making area detector.
Return to the ADCore directory, and now enter the iocBoot directory. Open commonPlugins.cmd, and ensure the following is uncommented:
# Optional: load NDPluginBar plugin
NDBarConfigure("BAR1", $(QSIZE), 0, "$(PORT)", 0, 0, 0, 0)
dbLoadRecords("$(ADPLUGINBAR)/db/NDBar.template", "P=$(PREFIX),R=Bar1:, PORT=BAR1,ADDR=0,TIMEOUT=1,NDARRAY_PORT=$(PORT)")
set_requestfile_path("$(ADPLUGINBAR)/barApp/Db")
This will add ADPluginBar to the boot operation when the ioc is run.
Optionally: In the same directory, check the commonPlugin_settings.req file to make sure the following line is uncommented:
file "NDBar_settings.req", P=$(P), R=Bar1:
This has to do with the EPICS autosave feature, and currently is buggy. This is not required for Plugin operation and can be omitted.
Next in the configure directory at the top level of areaDetector, open the RELEASE_PRODS.local file, and add the following:
# Load the ADPluginBar plugin
ADPLUGINBAR=$(AREA_DETECTOR)/ADPluginBar
This will tell areaDetector to include ADPluginBar at compilation.
Then, in the CONFIG_SITE.local.$(YOUR HOST) file, ensure that the following is defined:
# OPENCV_LIB and OPENCV_INCLUDE variables should not be defined if using the opencv system library in a default location
WITH_OPENCV = YES
OPENCV = /usr
#OPENCV_LIB = $(OPENCV)/lib64
#OPENCV_INCLUDE = -I$(OPENCV)/include
# ZBAR_LIB and ZBAR_INCLUDE variables should not be defined if using the zbar system library in a default location
WITH_ZBAR = YES
ZBAR = /usr
#ZBAR_LIB = $(ZBAR)/lib64
#ZBAR_INCLUDE = -I$(ZBAR)/include
Simply replace the variable to give your path to OpenCV and zbar includes. Make sure that WITH_OPENCV and WITH_ZBAR are set to "YES"
Next, in CONFIG_SITE.local, in the same directory, make sure that WITH_OPENCV, OPENCV_EXTERNAL, WITH_ZBAR, and ZBAR_EXTERNAL are all set to "YES"
Once you have done all of this, compile ADSupport, then ADCore, and then run
make -sj
in the ADPluginBar directory to compile it.
You have now installed the ADPluginBar Plugin.
To use ADPluginBar with CSS, place the provided .opi screens into your CSS setup, and link to it appropriately. The plugin supports 8 and 16 bit images in Mono or RGB formats. Inverted barcodes are supported as well but only in 8 bit formats. In order to view detected barcodes live, you may use any EPICS image viewer such as ImageJ, NDPluginStdArrays, or NDPluginPva, by setting the NDArrayPort to BAR1, or whichever port the plugin was assigned. This will display the image that the plugin processes, along with a blue bounding box around barcodes detected.
| PV | Comment |
|---|---|
| BarcodeMessage(1-5) | The message contained within the decoded barcode |
| BarcodeType(1-5) | The type of the decoded barcode i.e. CODE-128, QR-Code etc. |
| NumberCodes | Live count of the number of decoded bar codes in the current image |
| InvertedBarcode | Toggle between processing standard and inverted barcodes |
| CodeCorners | Allows for selecting which detected code's corners to track in corner PVs |
| UpperLeftX | X-coordinate of the upper left corner of the detected barcode |
| UpperRightX | X-coordinate of the upper right corner of the detected barcode |
| LowerLeftX | X-coordinate of the lower left corner of the detected barcode |
| LowerRightX | X-coordinate of the lower right corner of the detected barcode |
| UpperLeftY | Y-coordinate of the upper left corner of the detected barcode |
| UpperRightY | Y-coordinate of the upper right corner of the detected barcode |
| LowerLeftY | Y-coordinate of the lower left corner of the detected barcode |
| LowerRightY | Y-coordinate of the lower right corner of the detected barcode |
There are some limitiations to the current release of the NDPluginBar plugin:
- Inverted barcodes only support 8-bit images
- Processing time can range between 25 msec and 100 msec, meaning that fast cameras with large images need to be set to a low framerate to avoid overbuffering the plugin. Ideally, a 5 FPS feed would avoid such issues. When testing a 30 FPS feed on an 800x600 8-bit image, when multiple barcodes were on screen, dropped frames did occur.
- When camera is not stable, barcode detection "flickers" meaning that it detects the barcode then loses it then detects it again. This problem is mitigated by a stable camera and a higher resolution.
- When viewing the live barcode detection feed, one dimensional barcodes are generally not read around all 4 corners like QR codes, resulting in a somewhat inaccurate bounding box
For any other issues or limitations, please feel free to submit an issue on the ADPluginBar github page: https://github.com/jwlodek/ADPluginBar