What Are the Different Types of Image Sensors?

Currently, the two most common types of image sensors on the market (covering 90% of usage) are CCD (Charge-Coupled Device) and CMOS (Complementary Metal-Oxide-Semiconductor).

Different Sensor Sizes

Both CCD and CMOS sensors come in various sizes, such as Full Frame (~24mm × ~36mm) and APS-C (~15mm × ~24mm). Each camera manufacturer has slightly different dimensions for their sensors, which is a key factor influencing the unique image quality between brands.

For example, Fujifilm’s APS-C sensors are slightly larger than those of Canon and Nikon. Additionally, Fujifilm employs a unique arrangement of RGB color filters (as shown in the attached image), which contributes to superior image quality. Due to this, Fujifilm prioritizes APS-C sensors over Full-Frame, as their APS-C images often rival those from Full-Frame cameras in terms of file size and quality.

What’s Inside an Image Sensor?

Regardless of whether the sensor is CCD or CMOS, it consists of pixels (as discussed in Article 01). The accompanying image illustrates the typical structure of a pixel, which includes four key components:

1. Microlenses: These tiny lenses gather and direct light onto the sensor.
2. RGB Color Filter: This layer acts as a filter to separate colors before they reach the photodiodes.
3. Photodiodes: These detect the color of each pixel after blending Red, Green, and Blue (RGB). Depending on the manufacturer, sensors can recognize millions to billions of colors (e.g., a 24-bit RGB sensor can display approximately 16.7 million colors).
4. Electrical Signal Output: This component converts light into an electrical signal, which is then processed and saved as an image file. (Additionally, noise is generated at this stage—a topic that will be covered in a separate article.)

Understanding these components helps explain how different sensors impact image quality, color accuracy, and noise levels in photography. Stay tuned for more insights on image noise and sensor technology in upcoming articles!