A TECHNICAL HISTORY OF

CAMERA

VOL. 1

IMAGE PROCESSING

2The camera is now ubiquitous in our daily life as well as in image processing, but do

you know how it was born and how it evolved? This booklet describes the evolutionary

history of the camera from its birth to the current mainstream digital camera.

Structure of camera obscura and pinhole camerasFig. 1

Object

Light shield

Lens

Dark box (camera obscura)

Reflector (reflecting mirror)

Ground glass

Put a sheet of paper on this surface and trace the formed image with a pen.

1. Birth of the Camera

The history of camera images dates back to the B.C. era when camera obscura, which means dark

room, was the ancestral device of the current camera. The camera obscura was an optical device that

projects an upside-down image of an object using the light coming into a dark room through a small hole.

It used exactly the same mechanism as pinhole cameras. Eventually, from the 16th century, it was

developed into a device composed of a lens, dark box, and reflecting mirror. This device was used as a

drawing aid when artists made sketches of landscapes and drew portraits.

In 1839 a Frenchman, Daguerre, invented the daguerreotype (silver-plate photography) camera. Then

about 30 years later, Maddox invented the dry plate in Britain. It is said that the oldest photo in Japan was

taken with the daguerreotype camera.

With these inventions, the age when the subject was portrayed by human hands came to an end, and the

age of the camera, in which the captured image is recorded using photosensitive material, began.

3Full-size Half-size

Twice the number of photos per roll

36 mm

18 mm

35 mm

24 mm

Perforation

Half the size of a standard frame

24 mm

2. Film (Silver Halide) Camera

The photosensitive material, on which captured images are recorded, has been continuously changing for

over 170 years since the camera was born. Starting from the silver plate, the photosensitive material

evolved to the wet plate and then to the dry plate, and eventually film rolls were invented. Film rolls

enabled cameras to record multiple photos on one roll by advancing the film one frame at a time. In

response to this progress, various types of film cameras were developed to accept differently-sized films

such as 16 mm, 4 x 5 cm and 6 x 6 cm. In addition, the half-framed camera, which can double the number

of frames on one roll, was introduced to the market. The reason that film cameras are also known as silver

halide cameras is because the captured image is recorded by exposing compounds like silver halide to

light. The most widespread type of camera film used was the 135 film (better known as 35 mm film), which

was the standard size of films used for movies. Reversal film, which produces vivid colours, was also used

to make slides.

Different sizes of frames on 135 filmFig. 2

4Camera obscura

1900 1945 2000 2010

Leica

Thin-body + lens barrel typeBellow typeBox type

CalotypeDaguerreotype

Wet plate

1839

1851

1878

Industrialised production of dry plates

18881925

Dry plate g Sheet filmRoll film35 mm film

Electronic image

3. Popularisation and Miniaturisation Promoted by the Development of Electronics

Surprisingly, the application of electronic technologies to cameras started fairly early, dating back to the

1950s when the electronically-controlled automatic exposure metre was developed. This innovation freed

photographers from the troublesome procedure of adjusting shutter speeds and apertures. Further,

spurred by the introduction of the autofocus (automatic focusing) function and automatic strobe lights, the

camera gradually became popular among ordinary people. At the same time, the transistors used for

electronic control circuits were replaced by ICs, which expedited the miniaturisation of the camera. The

trends of popularisation and miniaturisation have been further accelerated with the development of digital

cameras.

Evolution of the camera and the worlds first autofocus cameraFig. 3

Year

5(image processing engine)

DSP

Image processing deviceA/D converter

(liquid crystal, EL, etc.)

Monitor screen

(temporary storage)

DRAM

Various memory cards

lenstarget

Digital camera example

(CCD&CMOS)

Image sensor

4. Digital Camera

When film cameras were in their heyday in the 1980s, the camera world marked another development. It

was the invention of the digital still camera. This newcomer fascinated the public with its convenient

features: the elimination of the DPE steps (development, printing, and enlargement) and the immediate

display of captured images on the LCD monitor for users to check them. Less than 20 years after its

release, it has surpassed the film camera in both production and shipment volumes, taking the lead in the

camera industry.

The captured image is converted into pixels using semiconductor image sensors (image sensing devices)

and photodiodes that detect light. For example, a five megapixel digital camera creates a full array of

image data using five million tiny photodiodes.

Mechanisms of digital camerasFig. 4

6Reproduced image

Original analogue signals

Original analogue signals

The signals are sampled to a fine degree.

The analogue signals carry noise

The data is quantised to a fine degree.

Accurate images can be obtained, though processing requires a longer time because of the large volume of data.

The noise is mixed into the image, which causes blurring.

The signal processing of image data is simple.

The signals carry noiseOriginal raw signals

Film camera

Digital camera

5. What Is the Difference between a Film Camera and a Digital Camera?

The biggest difference lies in the process to record a captured image. The film used for silver halide

cameras played two roles at a time: capturing the image and recording the image. On the other hand, the

image sensor on a digital camera divides these roles by first capturing the image and then recording the

image in semiconductor memory. This explains how two or more captured images are recorded on one

frame if you forget to advance the film and how recording memory can be repeatedly used by deleting the

image data stored in it. Moreover, the film camera records the captured images as they are, while the

digital camera performs sampling (constant quantisation of the changes in exposure) before recording the

image, which makes it possible to acquire highly stabilised and reproducible image data.

Film camera recording raw images vs. digital camera performing samplingFig. 5

Reproduced image

(Due to inappropriate exposure, the image is out of focus.)

73D image display

Left eye

Left Right Left Right Left Right

The 3D image is created by projecting the left and right eye images sequentially, not simultaneously.

The 3D image appears in this slit zone

Light permeable parts

To create this state, shutters like a liquid crystal shutter, are used.

Light impermeable parts

6. CCD Camera

The evolution of the digital camera continues with the development of the CCD (charge-coupled device)

image sensor which increases the photosensitivity of photodiodes. CCDs are used in a variety of cameras

such as compact microscope cameras, camera cell phones, compact digital cameras, and large DSLR

cameras. The CCD provides the functionalities to meet a wide range of application needs including those

for astrophotography and security surveillance, and is also used for the autofocus function and for

exposure control. Furthermore, 3D cameras, which have been recently introduced into the market, capture

a realistic image exactly as the human eye would recognise the object by equipping a CCD camera with

two lenses. On the other hand, the use of the CMOS image sensor, which has often been used for night

vision cameras, is increasing.

Mechanisms of the CCD and 3D camerasFig. 6

Right eye

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Copyright (c) 2012 KEYENCE CORPORATION. All rights reserved. TechHistory1-WW-EN0724-GB 1072-1 E 600B22 Printed in JapanThe information in this publication is based on KEYENCEs internal research/evaluation at the time of release and is subject to change without notice.

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