Image Formation on Camera

How does the human eye work?

Our eyes capture and focus light like a camera. Below are the steps of how an eye works:

1. Light rays enter the eye through the cornea.
2. Through the cornea, light rays pass to the pupil.
3. The amount of light which is passed through the pupil is controlled and maintained by iris.
4. From Iris, the light hits the lens. A lens is a transparent structure.
5. From lens, light rays focus onto the retina.
6. When the light rays reach the retina, the light-sensitive nerve layer is activated in which the image appears inverted.
7. The optic nerve carries signals of light, dark and colors in the brain which assembles all the signals into our vision or we can say image.

Image formation on analog cameras

In analog cameras, an image is formed by a chemical reaction which takes place on the strip. A 35mm strip is used in an analog camera. These strips are coated with silver halide. Silver halide is a chemical substance.

Light rays are small particles known as photon particles. This photon particle passes through the camera and reacts with silver halide particles on the strip. And it generates a negative of the image.

Image formation on digital cameras

In digital cameras, image formation is not through the chemical reaction. Rather than, it is more complex. A CDD array of sensors is used to form an image.

Image formation through CCD array

CDD stands for Charge Couples Device. Like other sensors, CCD is an image sensor. The image sensor senses the value and converts it to an electric signal.

CCD is in the shape of an array or a rectangular grid. Each cell in a rectangular grid contains a sensor which senses the intensity of photon.

In digital camera when light rays fall on the object, light rays reflect back after striking the object and allow it to enter inside the camera.

In CCD array, each sensor has an analog sensor in which light strike on the chip and each sensor is electrically charged. The response of the sensor depends on the number of light rays which strikes on the surface of the sensor.

A Complete image is achieved by the formation of a 2-dimensional CDD array.

Introduction to pixel

In CCD array, each sensor refers to an individual pixel. Each number of a sensor is equal to each number of pixels. it means that one sensor can have only one value.

Storing image

In CCD array, charges which are stored are converted into voltage per pixel at a time. Using some additional circuits this voltage is converted into digital information and then stored. Quality of the image depends on the CCD array that has been used. Every company that manufactures digital camera has its own CCD sensor.