Exposure, Gain & Processing Speed

This page explains how exposure, gain, and gamma settings influence image capture quality and inspection performance in the OV20i system. Proper tuning can balance speed, brightness, and model accuracy.

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Exposure

Exposure time is how long the image sensor collects light for a frame.

Setting	Effect
Short Exposure	Darker image, sharper motion capture
Long Exposure	Brighter image, risk of motion blur

Exposure time directly affects cycle time.

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Gain

Gain is a digital amplifier that brightens the image after light has been captured — like ISO on a DSLR.

Setting	Effect
Low Gain	Clean image, may be too dark
High Gain	Brighter image, adds grain/noise

Use gain to boost brightness without increasing exposure.

warning

Too much gain can hurt classifier accuracy due to noise.

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Gamma

Gamma adjusts the brightness curve of the image — enhancing contrast and mid-tones.

Setting	Effect
Low Gamma (<1)	Boosts shadows, reduces highlights
High Gamma (>1)	Boosts highlights, flattens shadows
Gamma = 1	Linear curve (no correction)

Use gamma to fine-tune contrast after lighting and exposure are stable.

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Impact on Processing Speed

Setting	Affects Speed?	Why?
Exposure	✅ Yes	Longer exposures = delayed capture
Gain	❌ No	Post-capture adjustment
Gamma	❌ No	Image processing step, minimal effect

Only exposure directly delays image capture and total cycle time.

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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

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✅ Best Practices

• ✅ Start with low exposure and moderate gain
• ✅ Use Test Image in the HMI to visualize lighting effects
• ✅ If parts are blurry, reduce exposure before changing gain
• ✅ Avoid excessive gain — keep noise low for better AI accuracy
• ✅ Gamma is best used for visual tuning, not brightness correction