ContinuousCapture.py

The ContinuousCapture program is a simple example for a continuous acquisition.

Program location

The source file ContinuousCapture.py can be found under:

%INSTALLDIR%\apps\Python\ContinuousCapture\

Note

If you have installed the package without example applications, this file will not be available. On Windows® the sample application can be installed or removed from the target system at any time by simply restarting the installation package.

ContinuousCapture example:

1. Opens a Balluff device.
2. Snaps images continuously (without display using Linux).

Console Output

[0]: BF000306 (mvBlueFOX-202C, Family: mvBlueFOX, interface layout: DeviceSpecific)

Please enter the number in front of the listed device followed by [ENTER] to open it: 0
Using device number 0.
Press [ENTER] to end the application
Initialising the device. This might take some time...
Info from BF000306: FramesPerSecond: 28.655660, ErrorCount: 0, CaptureTime_s: 0.104195
Info from BF000306: FramesPerSecond: 28.655636, ErrorCount: 0, CaptureTime_s: 0.104017
Info from BF000306: FramesPerSecond: 28.655659, ErrorCount: 0, CaptureTime_s: 0.104153
Info from BF000306: FramesPerSecond: 28.655636, ErrorCount: 0, CaptureTime_s: 0.104072
Info from BF000306: FramesPerSecond: 28.655660, ErrorCount: 0, CaptureTime_s: 0.104234

How it works

The continuous acquisition starts a thread that continuously requests images from the device.

First of all the user is prompted to select the device he wants to use for this sample:

pDev = devMgr.getDevice(devNr)
pDev.open()

Then after the device has been initialized successfully a continuous acquisition is started via the exampleHelper.

Accessing the pRequest object can be done after it has been checked using the pRequest.isOK function. The image attached to the request can then be processed and/or displayed if the request does not report an error.

requestNr = fi.imageRequestWaitFor(10000)
if fi.isRequestNrValid(requestNr):
    pRequest = fi.getRequest(requestNr)
    if pRequest.isOK:
        ...

Source code

import os, platform, sys
# import all the stuff from our SDK into the current scope
from mvIMPACT import acquire
# import all the helper functions for the examples using our SDK such as 'conditionalSetProperty' into the current scope
# If you want to use this module in your code feel free to do so but make sure the 'Common' folder resides in a sub-folder of your project then
from mvIMPACT.Common import exampleHelper
 
# For systems with NO mvDisplay library support
#import ctypes
#import Image
#import numpy
 
devMgr = acquire.DeviceManager()
pDev = exampleHelper.getDeviceFromUserInput(devMgr)
if pDev == None:
    exampleHelper.requestENTERFromUser()
    sys.exit(-1)
pDev.open()
 
print("Please enter the number of buffers to capture followed by [ENTER]: ", end='')
framesToCapture = exampleHelper.getNumberFromUser()
if framesToCapture < 1:
    print("Invalid input! Please capture at least one image")
    sys.exit(-1)
 
# The mvDisplay library is only available on Windows systems for now
isDisplayModuleAvailable = platform.system() == "Windows"
if isDisplayModuleAvailable:
    display = acquire.ImageDisplayWindow("A window created from Python")
else:
    print("The display library of this SDK is not available on this('" + platform.system() + "') system. Consider using the PIL(Python Image Library) and numpy(Numerical Python) packages instead. Have a look at the source code of this application to get an idea how.")
 
fi = acquire.FunctionInterface(pDev)
statistics = acquire.Statistics(pDev)
 
while fi.imageRequestSingle() == acquire.DMR_NO_ERROR:
    print("Buffer queued")
pPreviousRequest = None
 
exampleHelper.manuallyStartAcquisitionIfNeeded(pDev, fi)
for i in range(framesToCapture):
    requestNr = fi.imageRequestWaitFor(10000)
    if fi.isRequestNrValid(requestNr):
        pRequest = fi.getRequest(requestNr)
        if pRequest.isOK:
            if i%100 == 0:
                print("Info from " + pDev.serial.read() +
                         ": " + statistics.framesPerSecond.name() + ": " + statistics.framesPerSecond.readS() +
                         ", " + statistics.errorCount.name() + ": " + statistics.errorCount.readS() +
                         ", " + statistics.captureTime_s.name() + ": " + statistics.captureTime_s.readS())
            if isDisplayModuleAvailable:
                display.GetImageDisplay().SetImage(pRequest)
                display.GetImageDisplay().Update()
            # For systems with NO mvDisplay library support
            #cbuf = (ctypes.c_char * pRequest.imageSize.read()).from_address(int(pRequest.imageData.read()))
            #channelType = numpy.uint16 if pRequest.imageChannelBitDepth.read() > 8 else numpy.uint8
            #arr = numpy.fromstring(cbuf, dtype = channelType)
            #arr.shape = (pRequest.imageHeight.read(), pRequest.imageWidth.read(), pRequest.imageChannelCount.read())
 
            #if channelCount == 1:
            #    img = Image.fromarray(arr)
            #else:
            #    img = Image.fromarray(arr, 'RGBA' if alpha else 'RGB')
        if pPreviousRequest != None:
            pPreviousRequest.unlock()
        pPreviousRequest = pRequest
        fi.imageRequestSingle()
    else:
        # Please note that slow systems or interface technologies in combination with high resolution sensors
        # might need more time to transmit an image than the timeout value which has been passed to imageRequestWaitFor().
        # If this is the case simply wait multiple times OR increase the timeout(not recommended as usually not necessary
        # and potentially makes the capture thread less responsive) and rebuild this application.
        # Once the device is configured for triggered image acquisition and the timeout elapsed before
        # the device has been triggered this might happen as well.
        # The return code would be -2119(DEV_WAIT_FOR_REQUEST_FAILED) in that case, the documentation will provide
        # additional information under TDMR_ERROR in the interface reference.
        # If waiting with an infinite timeout(-1) it will be necessary to call 'imageRequestReset' from another thread
        # to force 'imageRequestWaitFor' to return when no data is coming from the device/can be captured.
        print("imageRequestWaitFor failed (" + str(requestNr) + ", " + acquire.ImpactAcquireException.getErrorCodeAsString(requestNr) + ")")
exampleHelper.manuallyStopAcquisitionIfNeeded(pDev, fi)
exampleHelper.requestENTERFromUser()