1. Digital television systems (DTS)
Camera
Technical Univ. of Kosice
Faculty of Electrical Engineering and Informatics
Lˇ. Maceková, 2017

2. (Wikipedia )
A camera is an optical instrument for recording or capturing images, which may be stored locally, transmitted to another location, or both.
The images may be individual still photographs or sequences of images constituting videos or movies.
The camera is a remote sensing device as it senses subjects without any contact 
The word camera comes from camera obscura, which means "dark chamber" and is the Latin name of the original device for projecting an image of external reality onto a flat surface
The modern photographic camera evolved from the camera obscura. 
The functioning of the camera is very similar to the functioning of the human eye. 

3. Functional description
A camera may work with the light of the visible spectrum or with other portions of the electromagnetic spectrum.
Optical device - creates image of an object or scene and records it on an electronic sensor or photographic film - basic design: light enters an enclosed box through a converging lens/convex lens and an image is recorded on a light-sensitive medium(mainly a transition metal-halide).
A shutter mechanism controls the length of time that light can enter the camera.
Most photographic cameras allow a person to view the scene to be recorded, allow for a desired part of the scene to be in focus, and to control the exposure so that it is not too bright or too dim - a display, often a liquid crystal display (LCD), permits the user to view scene to be recorded and settings such as ISO speed, exposure, and shutter speed.
movie camera or a video camera records a series of static images in rapid succession, commonly at a rate of 24 frames per second. When the images are combined and displayed in order, the illusion of motion is achieved.
fig. [Wikipedia]

4. History
The forerunner to the photographic camera was the camera obscura (see fig.). Camera obscura (Latin for "dark room") is the natural optical phenomenon that occurs when an image of a scene at the other side of a screen (or for instance a wall) is projected through a small hole in that screen and forms an inverted image (left to right and upside down) on a surface opposite to the opening
The use of a lens in the opening of a wall or closed window shutter of a darkened room to project images used as a drawing aid has been traced back to cca Since the late 17th century portable camera obscura devices in tents and boxes were used as a drawing aid.
The first person to use the known chemistry to create images was Thomas Wedgwood. To create images, Wedgwood placed items, such as leaves and insect wings, on ceramic pots coated with silver nitrate, and exposed the set-up to light. These images weren't permanent, however, as Wedgwood didn't employ a fixing mechanism yet.
Fig.: [Wikipedia] The Giroux daguerreotype camera, the first to be commercially produced.

5. Film camera
Digital camera

6. The use of photographic film was pioneered by George Eastman, who started manufacturing paper film in 1885 before switching to celluloid in 1889 – Kodak camera ... establishing the movie industry by end of 19th century.
the single-lens reflex camera (SLR) is provided with a mirror to redirect light from the picture taking lens to the viewfinder prior to releasing the shutter for composing and focusing an image.
Digital camera
The first camera using digital electronics to capture and store images was developed by Kodak engineer Steven Sasson in He used a charge-coupled device (CCD) provided by Fairchild Semiconductor, which provided only 0.01 megapixels to capture images. Sasson combined the CCD device with movie camera parts to create a digital camera that saved black and white images onto a cassette tape.
Later, cassette tapes were replaced by flash memory.
In 1986, Japanese company Nikon introduced the first digital single-lens reflex (DSLR) camera, the Nikon SVC

7. Camera controls
Focus
Aperture
Shutter speed
White balance
Metering
Film speed
Autofocuspoint
Focal length and type of lens (normal, long focus, wide angle, telephoto, macro, fisheye, or zoom)
Filters 
Inherent sensitivity.
The nature of the light recording material

8. Focal length and F-stop
F-stop has actually two meanings. One indicatesthe exposure setting's aperture value. The other shows the overall brightness of the lens. The term "F-stop" indicates the brightness at maximum aperture and describes lens performance. The brightness at maximum aperture is also dependent on the diameter of the lens, and as diameter increases so does lens brightness.

9. Spherical length
Aspherical length
Aspherical lenses can optimally correct aberration (When light refracts inside the lens, image quality is degraded.), resulting in light rays being focused on a single, ideal point.

10. How a CCD converts light to voltage

11. CMOS Image sensor
In a CMOS image sensor, each pixel consists of a photodiode and a switch that employs a CMOS transistor. The signal from each pixel is amplified. Another switch is mounted to each of the photodiodes, which are arranged in a lattice pattern, and the successive operation of these switches allows each pixel to be directly read and its data to be transferred at high speed.

12. Digital camera signal processing flow

13. Adjusting white balance with digital camera
Adjusting the white balance decreases R (red) and increases both G (green) and B (blue).