Decoding the Mystery: How to Obtain PayloadSize from the GenICam Reference Implementation
Understanding the Problem:
Many developers using GenICam, the standard interface for machine vision cameras, struggle to find a straightforward way to access the PayloadSize parameter from the GenICam Reference Implementation (RI). This information is crucial for various tasks like memory allocation and image processing. This article aims to clarify the process and provide a practical solution.
Scenario and Original Code:
Let's imagine a scenario where we need to determine the PayloadSize of a camera using the GenICam RI. The code snippet below showcases a typical attempt that fails to provide the desired result:
#include <GenICam/GenICam.h>
int main()
{
// Initialize GenICam and connect to the camera
// ...
// Attempt to access the PayloadSize parameter
GenICam::gcstring payloadSizeString = camera->GetNode("PayloadSize");
// This code throws an exception: "Node not found"
return 0;
}
Analysis and Clarification:
The issue lies in how the PayloadSize parameter is represented within the GenICam RI. While it is a crucial value, it is not directly accessible as a single node named "PayloadSize." Instead, it needs to be calculated from other available nodes.
Here's the Breakdown:
- Understanding the Structure: The GenICam RI defines
PayloadSizeas the product of theWidthandHeightof the image, considering the pixel format. - Accessing the Data: You need to obtain the
WidthandHeightvalues from the "Width" and "Height" nodes respectively. Additionally, you need to retrieve the "PixelFormat" node to identify the size of each pixel.
Practical Solution:
Here's the modified code snippet that correctly obtains the PayloadSize:
#include <GenICam/GenICam.h>
int main()
{
// Initialize GenICam and connect to the camera
// ...
// Retrieve Width, Height, and PixelFormat nodes
GenICam::gcstring widthString = camera->GetNode("Width");
GenICam::gcstring heightString = camera->GetNode("Height");
GenICam::gcstring pixelFormatString = camera->GetNode("PixelFormat");
// Get the actual values
int width = widthString->GetValue();
int height = heightString->GetValue();
std::string pixelFormat = pixelFormatString->GetValue();
// Calculate the PayloadSize based on the pixel format
size_t payloadSize;
if (pixelFormat == "Mono8") {
payloadSize = width * height;
} else if (pixelFormat == "RGB8") {
payloadSize = width * height * 3;
} else {
// Handle other pixel formats as needed
// ...
}
// Now you have the correct PayloadSize value
std::cout << "PayloadSize: " << payloadSize << std::endl;
return 0;
}
Additional Value and Optimization:
- Error Handling: The provided code snippet should be expanded to include error handling for cases where nodes might be unavailable or if the pixel format is not recognized.
- Generality: Instead of hardcoding specific pixel formats, consider using a lookup table or a dedicated function to map pixel formats to pixel sizes.
- Documentation: Thorough comments in your code help you and other developers understand the logic behind the calculations.
Conclusion:
Obtaining the PayloadSize from the GenICam RI requires a slightly different approach compared to directly accessing a single node. By understanding the structure and utilizing the correct nodes, you can successfully extract the necessary information for your image processing needs.
References:
- GenICam Standard: https://www.genicam.org/
- GenICam Reference Implementation: https://www.genicam.org/downloads.html
Remember, this article provides a starting point for understanding the process. Always consult the GenICam documentation and your camera's specific specifications for a complete and accurate implementation.
