Camera Technology

Basics Overview

Basics of Camera Technology

Saugaato Rayray@satmac.com

Director & CEOSATMAC INFOSYS LTD.

Camera Technology ConceptsImage acquisition, processing, encoding

– Lenses

– Raster scanning

– CCD technology

– Image processing

– Video signals

Output

Image

AcquisitionProcess Encoding

Light

LensLens

Optical Optical BlockBlock

ImagerImager

GainGainGammaGamma

Color BalanceColor BalanceWhite ClipWhite Clip

Enhancement Enhancement

Analog / Digital OutputAnalog / Digital Output

Format Format ConversionConversion

& Digitization

Image Acquisition

• Lenses

• Optical block

• Imager

Lenses

•Zoom/Focus Control

–Fixed – e.g.- SNC-P1.

–Manual => Vari-focal- eg- CS-50P, DF-40P.

–Auto Zoom and Focus –eg - SNC-RZ30P.

Imager

• Sensor– CCD / CMOS

• Scanning– Interlaced / progressive

CCD vs. CMOS

CCD CMOS

Advantage

* High sensitivity

* High Quality

* Low power consumption

* High speed read-out

* Smear-less

* Easiness of consolidating chip

* Low Cost

Disadvantage

* Smear

* External pulse for the drive

* Larger in size.

* More power consumption.

* Noisy

* Low Image Quality.

* Low Sensitivity.

CCD Imagers

• CCD’s (Charge Coupled Devices) made their first commercial appearance in a camera in 1981. It uses solid-state technology

• There are three types of CCD imagers viz IT (Interline Transfer), FIT (Frame Interline Transfer) & FT (Frame Transfer)

• FIT sensors are the most expensive to produce & are primarily used in high end broadcast cameras. Now Sony has IT CCD with technology which give better results as FIT.

Miniaturization and SensitivityU

nit

cell

area

[um

]2

Pixels

1/4TypeDiagonal 4.5mm

1/2TypeDiagonal 11mm

1/3TypeDiagonal 6mm

Larger the size of CCD, more is the Sensitivity.

The size of an imager greatly determines the overall potential quality of an image.

The larger the area of any given type of CCD, the better the image quality.

Imager SizeImager Size

The imager size is the

diameter of the circle

Scanning

odd lines

Field one

even lines

Field two

Frame

All linesInterlaced Scanning --- odd lines and even lines scanned separately

PAL Scanning

25 frames per second2 fields per frame

50 fields per second

625 lines per frame312.5 lines per field

Processing technology

• Exposure

• White Balance

• Gamma Correction

• Day / Night

• DynaView

Exposure

Exposure is affected by• Mechanical Iris• Electronic shutter

– CCD Iris [auto shutter function]

• Electronic gain

Dark Bright

AGC

Incoming

Iris

or

gain

leve

l

Mechanical IrisElectronic shutter

Electronic Shutter

Time

Exp

osur

e In

tens

ity

Shutter

Slow <<< >>> Fast

Exposure time

Electronic Gain

Gain-up Output signal level

6 dB 2 times

9 dB 3 times

12 dB 4 times

18 dB 8 times

24 dB 16 times

As the Gain increases, the S/N ratio decreases !!

~ Sample picture ~

24dB gain up0dB (no gain up)

AGC (Automatic Gain Control)

• Circuitry that automatically adjusts the electronic amplification of the video signal to compensate for varying levels of scene illumination.

White Balance

Levels BalancedLevels UnbalancedCombination of R, G & B gives White, properly balanced RGB levels

gives perfect white.

Picture Sample

Before After

Properly BalancedWhite Level ..

Gamma Correction

Light Directed onto Camera Imager

Light Directed onto Camera Imager

Display System Gamma

Display System Gamma

Camera GammaCamera Gamma

CRT Brightness

CRT Brightness

Day/Night Mode

B/W mode Color mode

<--- Automatic ---><----- Manual ----->

Remove IR Cut Filter

Sensitivity Improvement technology

• IR light has high content of heat. During daylight it hampers image of ccd.• IR filter comes in place during Daylight, cutting off IR spectrum.• At night it is automatically removed to improve sensitivity of CCD.

DynaView

DynaView = One picture at One picture at Normal Shutter picture + high speed shutter picture

Normal Shutter speed: 1/60 or 1/50

High speed: 1/500 ~ approx 1/8000

Camera show a high light picture with about x8~10 brightness.

Technology Definition Minimum Illumination

• A measure of the least illumination that will produce an image at the highest Gain of the camera with the lens aperture set to full open.– Minimum Illumination specifications will be affected

by the lens used.

– Because the highest Gain is used, the image quality is affected by lower S/N Ratio.

Technology Definition Resolution

• A measure of the ability to image picture detail.– Vertical Resolution is limited to the number of scan lines

that make up the image. This theoretical limit for a PAL Video signal is 483 lines.(525 Lines - 42 lines of the Vertical Interval)

– Horizontal Resolution is the number of alternating black and white lines which can be imaged across 75% of the width of the picture. (Assuming PAL Video with a 4:3 Aspect Ratio)

– Horizontal resolution increases with size of the CCD and with the number of CCD sensors used in the camera.

What is the difference

• Sensitivity

• Image Quality

• Why Larger Imager is good

• About Lens

• PAL / NTSC

Sensitivity

• Sensitivity Depends on– Imaging cell size– Day / Night function– Super HAD, Exwave HAD technology– With or Without Color filter– Signal gain-up

Sensitivity

• Sensitivity Depends on– Imaging cell size

The bigger imager cell size become,

The Higher sensitivity goes.

Sensitivity

• Sensitivity Depends on– Imaging cell size

The bigger imager size become,

The Higher sensitivity goes.

Here is a question….

Sensitivity• Sensitivity Depends on

– Imaging cell size

The bigger imager size become,

The Higher sensitivity goes.

Q. Which has higher sensitivity

A. 1/3 inch 30k Pixels

B. 1/3 inch 60k Pixels

Sensitivity

• Sensitivity Depends on– Imaging cell size

The bigger imager size become,

The Higher sensitivity goes.

Q. Which has higher sensitivity

A. 1/3 inch 30k Pixels

B. 1/3 inch 60k Pixels

Sensitivity

• Sensitivity Depends on– Day / Night function

Normal Color Imager has IR filter

Sensitivity

• Sensitivity Depends on– Day / Night function

Normal Color Imager has IR filter

Without IR filter,

Tone of color will collapse

Imager will be easily affected by heat.

( IR is a heat ray )

Sensitivity• Sensitivity Depends on

– Day / Night function

Day / Night function cuts off the IR filter

in the night time

We can see image in very dark circumstances

(Notice : In Night mode, Image goes to B/W)

Sensitivity

• Sensitivity Depends on– Super HAD, Exwave HAD technology

One of Imager structure technology

Sensitivity

• Sensitivity Depends on– Super HAD, Exwave HAD technology

( Imager structure )

• Super HAD

• Exwave HAD

• Super Exwave

Sensitivity

• Sensitivity Depends on– Super HAD, Exwave HAD technology

( Imager structure )

• Super HAD– Higher Efficiency Micro lens Array before imager

– Good on both Day mode and Night mode

• Exwave HAD

• Super Exwave

Sensitivity

• Sensitivity Depends on– Super HAD, Exwave HAD technology

( Imager structure )

• Super HAD– Higher Efficiency Micro lens Array before imager

– Good on both Day mode and Night mode

• Exwave HAD– Higher Sensitivity to Infrared

– Good on night mode

• Super Exwave

Sensitivity• Sensitivity Depends on

– Super HAD, Exwave HAD technology( Imager structure )

• Super HAD– Higher Efficiency Micro lens Array before imager

– Good on both Day mode and Night mode

• Exwave HAD– Higher Sensitivity to Infrared

– Good with Day / Night function

• Super Exwave– Much higher sensitivity to Infrared

– Better with Day / Night function

Comparison of Hyper HAD CCD and Super HAD CCD Sensor Structure

On-chip Micro lens of Conventional CCD On-chip Micro lens of Super HAD CCD

Hyper HAD CCD Sensor Structure Super HAD CCD Sensor Structure

Exwave HAD

Wave Length [nm]

Rel

ativ

e R

espo

nse

The past CCD vs. Exwave HAD Spectral Sensitivity

The past CCD Exwave HAD

Super Exwave

Exwave HAD vs. Super Exwave

Exwave HAD Super Exwave

Exwave HAD vs. Super Exwave

　 　 　

＜ Exwave HAD＞ 0.7lx

　 　 　

＜ Super Exwave＞0.55lx

illumination

High

Low

Sensitivity

• Sensitivity Depends on– With or Without Color Filter

Color Imager = B / W Imager + Color Filter

Sensitivity

• Sensitivity Depends on– With or Without Color Filter

Color Imager = B / W Imager + Color Filter

Color Imager is just like B/W with Sunglasses

Sensitivity

• Sensitivity Depends on– With or Without Color Filter

Color Imager = B / W Imager + Color Filter

Color Imager is just like B/W with Sunglasses

The reason why color imager has lower sensitivity

Sensitivity

• Sensitivity Depends on– Signal gain-up

Sensitivity

• Sensitivity Depends on– Signal gain-up

• Some camera has more gain-up capacity.

Sensitivity

• Sensitivity Depends on– Signal gain-up

• Some camera has more gain-up capacity.

( Gain-up is amplification of signal from imager )

Sensitivity

• Sensitivity Depends on– Signal gain

• Some camera has more gain-up capacity.

( Gain-up is amplification of signal from imager )

• Even though Image may be noisy,we can get image in darker situation.

Sensitivity

• Sensitivity Depends on– Imaging cell size– Day / Night function– Imager structure– With or Without Color filter– DSP gain up

Image quality

• Image quality Depends on– Imaging cell number– With or Without DynaView Technology– With or Without Variable Gamma Curve

Image quality

• Image quality Depends on– Imaging cell number

Image quality

• Image quality Depends on– Imaging cell number

The more imaging cell become,

the higher image resolution goes.

Image quality

• Image quality Depends on– Imaging cell number

The more imaging cell become,

the higher image resolution goes.

(Notice : Higher resolution Imager have less

sensitivity.)

Image quality

• Image quality Depends on– With or Without DynaView Technology

Image quality

• Image quality Depends on– With or Without DynaView Technology

prevents dark area from going to absolute black,

While preventing bright area from going to absolute white.

Image quality

• Image quality Depends on– With or Without DynaView Technology

prevents dark area from going to absolute black,

While preventing bright area from going to absolute white.

By taking picture twice in one frame period.

Image quality

• Image quality Depends on– With or Without DynaView Technology

prevents dark area from going to absolute black,

While preventing bright area from going to absolute white.

By taking picture twice in one frame period.

1st. At slower shutter speed for dark area to be bright.

Image quality

• Image quality Depends on– With or Without DynaView Technology

prevents dark area from going to absolute black,

While preventing bright area from going to absolute white.

By taking picture twice in one frame period.

1st. At slower shutter speed for dark area to be bright.

2nd.At faster shutter speed for bright area to be dark.

Image quality

• Image quality Depends on– With or Without Variable Gamma Curve

Image quality

• Image quality Depends on– With or Without Variable Gamma Curve

• Enhancing Vividness of Image

Image quality

• Image quality Depends on– With or Without Variable Gamma Curve

• Enhancing Vividness of Image

– Taking brightest pixel of image to absolute white

– Taking darkest pixel of image to absolute black

Image quality

• Image quality Depends on– With or Without Variable Gamma Curve

• Enhancing Vividness of Image

– Taking brightest pixel of image to absolute white

– Taking darkest pixel of image to absolute black

– Taking reddest pixel of image to absolute red

– Enhancing solidity of object.

Why Larger Imager is good

• To achieve higher sensitivity,

The imaging cell must be larger.

• To achieve higher resolution

More imaging cell is needed.

Why Larger Imager is good

• To achieve higher sensitivity,

The imaging cell must be larger.

• To achieve higher resolution

More imaging cell is needed.

• What would you do,

if you want both sensitivity and resolution?

Why Larger Imager is good

• To achieve higher sensitivity, the imaging cell must be larger.

• To achieve higher resolution, more imaging cell is needed.

• What would you do,

if you want both sensitivity and resolution?

• Larger imager can achieve both of these.

Why Larger Imager is good

• To achieve higher sensitivity, the imaging cell must be larger.

• To achieve higher resolution, more imaging cell is needed.

• What would you do, if you want both sensitivity and resolution?

• Larger imager can achieve both of these.

• This is why larger imager is good.

Why Larger Imager is good

• To achieve higher sensitivity, the imaging cell must be larger.

• To achieve higher resolution, more imaging cell is needed.

• What would you do, if you want both sensitivity and resolution?

• Larger imager can achieve both sensitivity and resolution,

even though Larger imager is more expensive.

Why Larger Imager is good

• To achieve higher sensitivity, the imaging cell must be larger.

• To achieve higher resolution, more imaging cell is needed.

• What would you do, if you want both sensitivity and resolution?

• Lager imager can achieve both sensitivity and resolution,

even though Lager imager is more expensive.

1/3 > 1/4 > 1/6

About Lens

• Brightness

• Image Angle

• Iris Servo

About Lens

• Brightness

The smaller F value goes….

About Lens

• Brightness

The smaller F value goes….

the brighter

the lens become.

About Lens

• Brightness

The smaller F value goes….

the brighter

the bigger

the lens become.

About Lens

• Brightness

The smaller F value goes….

the brighter

the bigger

the more expensive

the lens become.

About Lens

• Image Angle

The smaller f value goes….

About Lens

• Image Angle

The smaller f value goes….

the wider

image angle become.

About Lens

• Image Angle

The smaller f value goes….

the wider

image angle become.

Wide Angle Lens..

About Lens

• Image Angle

The larger the f value goes….

About Lens

• Image Angle

The larger the f value goes….

the narrower

image angle become.

About Lens

• Image Angle

The larger the f value goes….

the narrower

image angle become.

Tele-Photo Lens..

About Lens• Image Angle

Vari-focal Lens can Change Image angle

like zoom lens.

About Lens

• Image Angle

Vari-focal Lens can Change Image angle

like zoom lens.

( With Vari-focal Lens,

Image will go out of focus, after changing Image Angle,

while image don’t go out of focus with ordinary zoom lens.

Vari-focal Lens is cheaper than ordinary zoom lenses)

End.