Digital imaging is not just “taking a picture.” It is a complex process that combines light, electronics, and digital technology. By understanding these basic ideas, we can better see the logic and scientific foundation behind image processing.

When light passes through a telescope and reaches the image sensor (CMOS), each pixel turns the incoming light into an electronic signal. These signals are then converted into numbers and saved as digital data, for example:
8-bit uses values from 0 to 255
16-bit uses values from 0 to 65,535

The more levels available, the more smoothly differences in brightness can be recorded.

An image sensor can only measure how strong the light is; it cannot see color by itself. To imitate how the human eye senses red, green, and blue light, a Bayer filter made of red, green, and blue color filters is placed over the pixels. If a pixel has only a green filter, it records only green light. The red and blue information is then estimated from nearby pixels.

In a monochrome camera, there is no Bayer filter. Instead, red, green, and blue filters are used one at a time to take three separate images, which are later combined into a single color image. Because this method does not rely on estimation, it can produce higher image detail.

Settings that can be adjusted during shooting:
Shutter Speed: Controls how long light reaches the sensor. Longer exposures create brighter images.
ISO: Increases the strength of electronic signals to brighten the image without adding more light.
White Balance: Adjusts the balance of red, green, and blue to correct color shifts.

Many people think that “post-processing” means creating fake images, but in fact, cameras already perform many automatic calculations on every photo. When we understand the process, we see that image processing is not about making things up—it is about correctly recovering the light that was captured.

Through the science of digital imaging, we do more than take photographs. We also gain insight into the mathematics of light and a deeper understanding of the universe.