Many engineers start with the default frame rate of a sensor and only revisit it when something stops working as expected. In SWIR imaging, that often means running into bandwidth limits, unstable processing loads, or image quality trade-offs that could have been optimized earlier.
The good news is that frame rate can often be fine-tuned directly through sensor timing settings, without changing hardware.
The frame rate is determined by:
Frame rate = Pixel clock / (VMAX × HMAX)
In most designs, the main adjustment point is VMAX, which defines the number of vertical lines in each frame.
- To increase frame rate, reduce VMAX
- To decrease frame rate, increase VMAX by adding vertical blanking lines
The second parameter is HMAX, which controls horizontal timing. It is usually fixed by the selected readout mode and output interface, but in some cases it can also be adjusted.
Be aware that increasing HMAX extends the line time, which may lead to:
- Higher dark current
- Increased noise
- Reduced overall image quality
Before changing timing values, it is worth checking a few basics:
- Keep VMAX and HMAX within the supported range of the selected sensor mode
- Confirm the resulting data rate fits your interface bandwidth and FPGA / SoC capacity
- Remember that frame rate changes can also affect integration time and exposure behavior
In practice, fine-tuning frame rate is often less about chasing the highest FPS and more about finding the right balance between image quality, system bandwidth, and application performance.
