Control Camera in BB

In this tutorial, we learn how to control Gain and ExposureTime in Building Block.

To control Gain and ExposureTime without BB, you may want to see Access and Set Device Info or arv-tool-0.8.

Prerequisite

• OpenCV (installed with sensing-dev SDK with -InstallOpenCV option)
• ion-kit (installed with sensing-dev SDK)

Tutorial

Get Device Information

To display image with ionpy, we need to get the following information of the device.

• Width
• Height
• PixelFormat

The previous tutorial or arv-tool-0.8 will help to get these values.

Build a pipeline

While the structurte of BB is the same as the tutorial that display 1-camera image, we need some small changes to enable Gain and ExposureTime setting.

In this tutorial, we can set Gain and ExposureTime manually by setting enable_control to true.

While port input is dynamic; i.e. it can be updated for each run, you can set static values in string via Param. For example, the value of Gain and ExposureTime is set by port to update in each run, and the key of these values are static, so whould be set by Param as follows:

// set params
Param enable_control("enable_control", true),
Param gain_key("gain_key", "Gain"),
Param exposure_key("exposure_key", "ExposureTime")

// set port values
double gain0 = 35.0;
double exposuretime0 = 50.0;
double gain1 = 47.0;
double exposuretime1 = 100.0;

gain_values = []
exposure_values = []

Node n = b.add(bb_name)(&gain0, &exposuretime0)
    .set_param(
        Param("num_devices", num_device),
        Param("frame_sync", true),
        Param("realtime_display_mode", true),
        Param("enable_control", true),
        Param("gain_key", "Gain"),
        Param("exposure_key", "ExposureTime")
    );

Now, we have set Gain and ExposureTime successfully!

note

While v23.11.01 requires BB to take a port for Gain and ExposureTime, you may take just an address of Gain and ExposureTime values for input.

Also, to enable BB to take these values as inputs, you have to add enable_control as Param input of BB.

why it does not work

gain_key and exposure_key are the feature key of GenICam to control device gain and exposure time. With SFNC (Standard Features Naming Convention) by emva; they are usually set Gain and ExposureTime; however, some device has different key.

In that case, you may need to change the name of the keys of param. This page to check how to list the available features.

Param("gain_key", <name of the feature to control gain>)
Param("exposure_key", <name of the feature to control exposure time>)

Execute the pipeline

The pipeline is ready to run. Each time you call run(), the buffer in the vector or output receive output images.

b.run();

Display with OpenCV

In the previous tutorials, we have just displayed the output image in each run. This time, you can update the value of Gain or ExposureTime. The following example shows how to increase Gain by 1.0 for every run bi updating gain_values and re-bind the updates.

while(user_input == -1)
{
    // dynamically update gain
    gain0 += 1.0;
    // JIT compilation and execution of pipelines with Builder.
    b.run(); 
}

Complete code

Complete code used in the tutorial is here.

why it does not work

• If you are using OpenCV that you install by yourself, please confirm that it is linked to your program appropriately.