Even/Odd Line Exposure
Even/Odd Line Exposure in a CMOS image sensor refers to a special operating mode where even-numbered lines and odd-numbered lines of the sensor array are exposed with different integration times (exposures).
How it works
- The pixel array is divided into two interleaved sets of rows:
- Even lines (rows 0, 2, 4, …)
- Odd lines (rows 1, 3, 5, …)
- The sensor’s timing and control circuits allow independent exposure control for each set.
- As a result, two images with different exposures are captured within a single frame readout:
- One image composed of even lines (short or long exposure)
- One image composed of odd lines (opposite exposure)
Why it’s useful
- High Dynamic Range (HDR)
- Captures bright and dark details simultaneously by combining the short-exposure and long-exposure data.
- Motion Analysis
- Alternating exposure settings can help analyze moving objects at different light levels or speeds.
- Specialized Scientific Imaging
- Enables capturing two “modes” of data in a single frame for faster acquisition.
Advantages
- No frame-to-frame delay — both exposures are captured in the same frame time.
- Reduced motion artifacts compared to taking two separate frames with different exposures.
- Higher temporal resolution for dual-exposure data capture.
Limitations
- Vertical resolution per exposure is halved (since each exposure uses only half the lines).
- Requires post-processing to reconstruct two full-resolution images.
- Not ideal for scenes with fine horizontal detail if reconstruction is needed.
