What Is an Image Sensor?
1 min read
Quick answer
An image sensor is a sensor that converts the light falling on it into a digital image. It's the heart of all digital cameras.
How Does It Work?
The sensor is made of millions of tiny light detectors (photodiode-based pixels). Each pixel converts the light falling on it into a voltage; these are digitized with an ADC to form the image.
CMOS vs CCD Difference
| Property | CMOS | CCD |
|---|---|---|
| Power consumption | Low | High |
| Speed | High | Medium |
| Cost | Low | High |
Where Is It Used?
Phones and cameras, security cameras, machine vision, barcode readers and automotive driver-assist systems.
Resolution and Frame Rate (FPS)
An image sensor is defined by two basic values: resolution (pixel count, e.g. 1920×1080) and frame rate (FPS) (images per second). Moving scenes need a high FPS, fine detail needs high resolution; both together increase the amount of data.
Common Mistakes
- Fixating on resolution: more pixels doesn't always mean a better image; pixel size and noise also matter.
- Low light: noise rises in low light.
- Lens mismatch: a lens suited to the sensor size must be chosen.
Frequently Asked Questions
CMOS or CCD?+
Today most devices use CMOS for its low power and cost; CCD remains in special high-quality applications.
What is a pixel?+
The smallest light-detection unit that forms the image; each carries the brightness/color information of one point.
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