DRAL Libraries

The Daisy Real-time Application Libraries, DRAL, are extension libraries for Daisy. They provide real-time functionality by using the on-board controller of Leutron PicPort^®/PicProdigy^® frame grabbers, allowing performing video control tasks independently from the application software and the main processor. Currently available are the Image Sequencer DRAL and the Image Preprocessing DRAL.

DRAL Overview

The Daisy Real Time Application Libraries, DRAL, are support modules that performs functions, which are not available with the standard Daisy programming, providing support for non-standard acquisitions.

The specific functionality of each DRAL can involve strict control over the acquisition hardware. In this case, the DRAL takes advantage of the on-board controller that the PicPort^®/PicProdigy^® frame grabber family features. This allowes running time-critical tasks such as complex acquisitions with coupled I/O handling (e.g. via optocouplers) with an external device. The controller is able to run two independent tasks at the same time without interfering with the system CPU.

The user application has not to take care about the instruction set of the hardware controller. Leutron Vision provides the DRAL to handle specific tasks.

DRALs are enhancement to the Daisy functionality, allowing real-time control over the acquisition. They are not intended to be a substitute for Daisy, therefore, user applications have still to use Daisy in the «normal» way to set the desired configurations.

The libraries are loaded by Daisy as needed, which means only when the user application is using them. In applications using only Daisy they are not wasting any memory or interfering with normal Daisy operations.

Each DRAL provides an interface through which the user application can set the proper parameters to achieve the desired results.

DRAL libraries are available in form of C++ classes. Alternatively, a simplified interface to DRAL is provided by the Orchid library.

Image Sequencer DRAL

The Image Sequecer DRAL is a support module to allow user applications to acquire sequences of images in the selected target buffer. It enables to:

• Acquire a sequence of images, i.e. place each image in different place in memory, in form of circular buffer. This for example enables to process one frame while another is being acquired.
• Base the start of a frame, subsequence or sequence acquisition on the frame grabber's on-board optically isolated input (referred as an external trigger in LV-SDS).
• Send trigger signal to camera to make immediate restart/reset (called asynchronous reset in LV-SDS documentation).
• Send output for flash to frame grabber's on-board optically isolated output, with possibility to set the pulse timing.
• Send notifications to the host application about when the acquisition goes through the preset checkpoints (end of frame, end of subsequence, end of sequence).
• Assure proper frame integration from 2 neighboring fields for cameras that support this mode.
• Acquire images from single or multiple cameras, connected to single or multiple frame grabbers, with minimized time needed to switch from one camera to another (in case of slave cameras the switch is done during vertical retrace).
• Acquire images in parallel in case the hardware configuration enables to do so (for example from 2 cameras on PicPort^®-Stereo).
• Acquisition in continue-on-request or pause-on-request mode.
• Scaling/clipping to desired image dimension is available if the hardware configuration enables to do so.
• A number of various run-time parameters can be changed during acquisition, like ADC levels or Brightness/Contrast, timing of flash output, camera reset delay etc.
• Fast switch from one camera to another (on the same frame grabber), controllable by the application.
• Possibility of external synchronization of multiple frame grabbers.

The Image Sequencer DRAL has, besides its base form, four extensions:

Flash

Extends the base DRAL class by possibility to control a flash, connected to on-board opto-isolated output. It is possible to set the flash timing, as well as to flash once for the whole frame, or twice, once for each field.

Asynchronous Reset

Enables to utilize so called Asynchronous Reset (by some cameras also referred as Restart/Reset). In this mode the camera can be reset at any time to start acquiring immediately a new field. Whenever the input trigger on the on-board opto-isolated input comes, PicPort^®/PicProdigy^® sends the reset signal to the camera with a defined delay, and receives either a single field/frame, or a sequence of fields/frames. The acquired images are then stored in CPU memory and accessible for image processing.

The typical usage of this class is in acquiring images of fast moving objects, namely on production lines.

Frame Integration

Some cameras provide so called Frame Integration mode, in which the camera is able to expose both fields of the frame in one time (usually using a single flash), and then send the two fields sequentially to the grabber. When the interlaced fields are combined into one frame, the result image is like from a (much more expensive) progressive scan camera, without a motion blur, caused normally by a different time of each field exposition.

This class enables to acquire images with combined interlaced fields into a single frame and to set the flash timing.

Frame Integration Asynchronous Reset

Some cameras enable to use both the above mentioned modes at once, i.e. to acquire with asynchronous reset and frame integration mode. This class supports such cameras.

PicPort^® & PicProdigy^® Demo Program

Some of the DRAL features are demonstrated in the Task 7.2 of PicPort^® & PicProdigy^® Demo program, supplied with LV-SDS 1.91 and later. This Task enables to explore interactively almost all of the DRAL functionality.

Image Preprocessing DRAL

The Image Preprocessing DRAL is a suport module that allows the application to perform some simple manipulations on the acquired images. This library can be used either standalone or in conjunction with the Image Sequencer DRAL. The module supports following functionality (more will be added in next releases of the LV-SDS):

Image processing

• Color decoder for cameras suporting the Bayer array encoding.
• Noise reduction at selectable factor.

Other features

• Possibility to define the image areas where the process is applied.
• Possibility to direct the resulting image to a specific window client area and/or a user defined buffer.
• Possibility to measure the execution time of each function.
• White balancing for color decoder function to increase color matching.

Important note: The Image Preprocesssing DRAL supports only the following color formats as input and output:

• Monochrome 8 bits
• RGB 24 bits
• RGB 32 bits

More Information

To get the full detailed information about DRAL and the other parts of the LV-SDS, please feel free to download the LV-SDS manual.

Complementary and Related Products 

LV-SDS

Daisy 

Object oriented C++ library providing an essential interface between hardware and the user appication. 

Orchid

High level library for developing interactive applications with a few lines of code in visual tools like Microsoft Visual Basic, Borland Delphi, Borland C++ Builder, etc. Available as a DLL or as an OCX component.

Camera editor 

Interactive application allowing simple setup of standard and non-standard cameras. 

Third Party Image Processing Software

Several well-known third party packages for real-time image processing and analysis are also supported. The packages include HALCON, Activ Vision Tools, NeuroCheck, and others. Please refer to our detailed software brochure (PDF) for more details.

Leutron Frame Grabbers and LVmPC^®

PicPort^® & PicPort^®-Pro Frame Grabbers

High quality, cost effective frame grabber line providing interface to various camera types: standard analog (color and monochrome), non-standard analog, LVDS, Camera Link. PicPort^®-Pro is a new board series based on FPGA architecture. Please refer to the product catalog to learn more about individual board types.

PicProdigy^® Frame Grabbers

High-end frame grabber line with similar architecture like PicPort^®-Pro boards, but providing some additional high-end features, especially on-board algorithm accelerators. Please refer to the product catalog to learn more about individual board types.

LVmPC^®

Ultra compact, mobile image processing system for industrial and machine vision, based on standard PC technology and Leutron's PicPort^®/PicProdigy^® frame grabbers.

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