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曝光、增益与处理速度
本页说明 OV20i 系统中 曝光、增益 与 伽玛 设置如何影响图像捕获质量和检测性能。适当的调谐可以在速度、亮度和模型精度之间取得平衡。
Exposure
Exposure time is how long the image sensor collects light for a frame.
| Setting | Effect |
|---|---|
| Short Exposure | 图像更暗，运动捕捉更清晰 |
| Long Exposure | 图像更亮，存在运动模糊的风险 |
Exposure time directly affects cycle time.
Gain
Gain is a digital amplifier that brightens the image after light has been captured — like ISO on a DSLR.
| Setting | Effect |
|---|---|
| Low Gain | 图像干净，但可能太暗 |
| High Gain | 图像更亮，增加颗粒感/噪声 |
Use gain to boost brightness without increasing exposure.
注意过高的增益可能由于噪声而降低分类器的准确性。
Gamma
Gamma adjusts the brightness curve of the image — enhancing contrast and mid-tones.
| Setting | Effect |
|---|---|
| Low Gamma (<1) | 提升阴影，降低高光 |
| High Gamma (>1) | 提升高光，拉平阴影 |
| Gamma = 1 | 线性曲线（无校正） |
Use gamma to fine-tune contrast after lighting and exposure are stable.
Impact on Processing Speed
| Setting | Affects Speed? | Why? |
|---|---|---|
| Exposure | ✅ Yes | 更长的曝光时间会导致捕获延迟 |
| Gain | ❌ No | 捕获后进行的调整 |
| Gamma | ❌ No | 图像处理步骤，影响较小 |
Only exposure directly delays image capture and total cycle time.
Timing Examples
| Condition | Exposure | Gain | Total Cycle Time |
|---|---|---|---|
| Bright Lighting | 2 ms | 5 dB | ~60 ms |
| Dim Lighting (Low Gain) | 6 ms | 0 dB | ~90 ms |
| Dim Lighting (High Gain) | 2 ms | 15 dB | ~60 ms |
| High Contrast w/ Gamma | 3 ms | 5 dB | ~65 ms |
✅ Best Practices
- ✅ 从低曝光和中等增益开始
- ✅ 在 HMI 中使用 Test Image 以可视化照明效果
- ✅ 如果部件模糊，请在改变增益之前先降低曝光
- ✅ 避免过度增益 — 为了提升 AI 准确性，应降低噪声
- ✅ 伽玛最适用于 视觉调谐，而非亮度校正