How to Configure Video Output and Image Processing with FLIR Lepton Thermal Camera Module

The FLIR Lepton® micro thermal camera module supports multiple video output formats for applications that require temperature data, high-contrast thermal imagery, or both. Selecting the appropriate output depends on whether the system requires radiometry and where automatic gain control (AGC) and other image processing will occur.

In this episode of Thermal Integration Made Easy, OEM engineers and developers learn how Lepton's thermal video pipeline works, including radiometric T-linear and T-stable output, 8-bit and 16-bit video, and on-camera versus host-based AGC. The video also explores plateau histogram equalization and development options for evaluating Lepton on Raspberry Pi, Windows, and USB-based platforms.

Key Takeaways

What video output options are available with FLIR Lepton?  

Lepton provides video output from different points within its image pipeline. The appropriate output depends on whether the application requires radiometric temperature data, high-contrast thermal imagery, or additional image processing on the host platform.

What is the difference between T-linear and T-stable output?

When radiometry is enabled, T-linear output provides 16-bit data that is linearly proportional to scene temperature and is the preferred option when temperature measurement is required. T-stable output stabilizes the camera output but requires an additional conversion to determine temperature.

When should T-linear output be used?

T-linear output should be used when radiometric temperature data is required. Lepton 2.5 and Lepton 3.5 support radiometry, and T-linear is enabled by default according to the video.

When should the 8-bit AGC interface be used?

The 8-bit AGC interface is generally appropriate when radiometry is not required, and the primary goal is to display thermal contrast within the scene.

What is Post-AGC RGB888 output? 

When AGC processing occurs on the camera, Lepton can provide Post-AGC RGB888 output. This output is suitable for systems that do not require radiometric temperature data and primarily need a high-contrast thermal image.

Can Lepton provide temperature data and high-contrast video at the same time? 

Lepton provides only one video output from the camera. When an application requires both temperature data and high-contrast imagery, AGC processing must be performed on the integrator's host platform using the radiometric output.

What is automatic gain control in thermal imaging?

Automatic gain control maps thermal image data into a displayable intensity range to improve scene contrast. It helps make effective use of the available 8-bit output space so temperature differences within the scene are easier to distinguish visually.

What is plateau histogram AGC?

Teledyne FLIR's plateau histogram AGC uses histogram equalization to optimize thermal image contrast and limit how strongly certain objects influence the resulting image. Compared with a basic linear transformation, plateau histogram equalization can provide greater contrast by making more effective use of the available output range.

Does every Lepton integration require custom AGC processing?

No. If radiometric data is not required, Lepton's RGB output can provide processed thermal imagery without requiring the integrator to develop a custom AGC. Custom AGC processing may be appropriate when an application requires both temperature data and optimized thermal imagery or has additional image-processing requirements.

What platforms can be used to develop and test with FLIR Lepton?

Raspberry Pi is commonly used for Linux and processor-based implementations. For Windows-based evaluation and testing, the video demonstrates the Lepton User App with the PureThermal board, which provides a standard USB connection and UVC streaming.

Products & Technology Featured

FLIR Lepton Micro Thermal Camera Module

FLIR Lepton is a compact longwave infrared (LWIR) thermal camera module designed for OEM integration. Developers can access thermal video, camera parameters, telemetry, and command and control functionality when integrating Lepton into processor-based systems and other thermal imaging applications.

Lepton SDK and Lepton User App

The Lepton SDK provides camera command and control over I2C, including the communication protocol, command construction, and byte packing. The Lepton User App provides a standard application for Windows-based development and testing when Lepton is paired with a PureThermal board.

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Engineering Documents

• Lepton Engineering Datasheet
• Lepton 3 Software Interface Description Document (IDD) Rev 303

Brochures

• Lepton Series Datasheet
• Lepton FS1 Datasheet
• Lepton Breakout Board V2.0 Datasheet

Certifications

• Lepton Thermal Core - Declaration of Compliance Rev 210
• Lepton Breakout Board - Declaration of Compliance Rev 120
• Lepton California Proposition 65 Declaration Rev 100
• Lepton RoHS Certificate of Compliance Rev 190