Download Recording Medium Part 2

Photography: Recording Medium (Film, CCD & CMOS and Printing Papers)
Introduction
Friends over the period we have understood the analog and the digital cameras and their usage.
Today we are going to talk about a little technical aspects of digital photography and analog
photography. in digital photography we have two recording mediums CCD and CMOS. In order
to understand the purpose and working of CCD and CMOS let us first understand some concepts.
As the digital world evolved. Alongside evolved the digital cameras and usage of films
photography faced a challenge. It had to compete with the faster and more portable medium. The
most important feature in digital cameras was its Image sensor which is responsible for
converting light rays into electronic signals which would be recorded over a digital medium.
Image Sensor: Let's see what are image sensors.
An image sensor is a device that converts an optical image into electronic signal. It is used
mostly in digital cameras and other imaging devices. Early analog sensors were video camera
tubes, most currently used are digital charge-coupled device that is CCD or complementary
metal–oxide–semiconductor (CMOS) active pixel sensors.
CCD: Charge Coupled Device
CCD is a device that uses quantity of electronic charges to represent an analog quantity this
refers to the image that is analog Quantity which is converted into electrical signals. The
electrical signals are recorded in succession to one another on the memory and thus making CCD
a Discrete time device. As an image sensor a CCD generally has an array of cells to capture light
image by the photo-electric effect. The packets of charge are not initially converted to electrical
signal, but rather moved from cell to cell by the coupling and decoupling of potential wells
within the semiconductor that makes up the CCD. At the end of the line the charges, from all the
different picture elements that is pixels, can be converted into electrical signals.
Let us now see the advantages of CCD:
1) As it uses different color filter for each color. It gives better precision and hence a better
image quality.
2) A CCD in a digital camera improves resolution compared with older technologies.
3) A good CCD can produce an image in extremely dim light, and its resolution does not
deteriorate when the illumination intensity is low
4) Some digital cameras produce images having more than one million pixels, yet sell for
under one thousand pounds or dollars.
5) CCDs are sensitive to a wide range of light levels.
Let us now see the disadvantages of a CCD
1) The principal disadvantage of a CCDs is that they are physically small and consequently can
image only a small region of sky.
2) The surface area of the CCD is smaller than a film plate so you get less sensitivity.
3) You can use an 8'X10" film camera if you want which gives more resolution and sensitivity
versus a one inch square CCD.
To conclude: Charge Coupled Device is one development in Digital imagining that has made
cameras available to even low class consumers. The smaller size or CCD has made it compact
and still gives a good efficiency. Although the quality of image is not matchable to that of a film
but when cost is a barrier it is better than anything else.
CMOS : Complementary Metal Oxide Semiconductor
CMOS that is complementary metal oxide semiconductors
complementary metal oxide semiconductor is a technology developed for constructing integrated
circuits. A CMOS Image sensor is an integrated circuit containing active pixel sensors where
each pixel contains a photo detector and active amplifier. The variants of CMOs are used in web
Cameras, Mobile cameras, Camcorders and some DSLR’s. Thus CMOS is proved to be an
alternative for a CCD. A CMOS is also known as active pixel sensor because it has individual
pixel sensor and thus sometimes the sensor is also known as Active pixel sensor imager.
Let us now see the advantages of CMOS:
First of all, it has a Low power consumption.
1) Because CMOS sensors are fabricated using the CMOS manufacturing process they are
much less expensive than CCD-based image sensors.
2) A CMOS camera is immune to the blooming effect where a light surface has overloaded the
sensitivity of the sensor, causing the sensor to bleed the light source onto the pixels.
3) APS pixels solve the speed and scalability issues of passive – pixel sensor.
4) They have less image lag, and require less specialized manufacturing facilities.
CMOS provides range of resolution from 352 by 288 that is point one Megapixel to 2592 into
1944 that is 5 Megapixel. The bottom line however is that the CMOS sensors read the image
more directly reducing the chance of an error due to "handling" thus less noise and a higher
contrast ratio.
CMOS devices use several transistors at each pixel to amplify and move the charge using more
traditional wires. Because each pixel on a image sensor has several transistors located next to it.
the light sensitivity of a CMOS chip is lower. Many of the photons hit the transistors instead of
the photo diode.
CCDs consume as much as 100 times more power than an equivalent CMOS sensor.
CCD sensors have been mass produced for a longer period of time, so they are more mature.
They tend to have higher quality pixels, and more of them.
Disadvantages of CMOS:
CMOS video sensor typically captures a row at time within approximately 1/60th or 1/50th of a
second. It may cause an image to tilt/distort or skew.
The standards of CMOS have still not touched to those of a CCD.
Resolution provided by CMOS is lesser than that of CCD.
Difference between CCD and CMOS
Let us compare CCD and CMOS:
The two image sensors find their way in their own fields. The Smaller Inexpensive CMOS into
mobile circuitry and Bigger CCD in the Cameras and telescopes.
CMOS generates upto 5 megapixel of images while the resolution of CCD depends upon the
device it is logged into.
CCD consumes more power than CMOS.
CMOS sensors are generally more susceptible to noise.
A CCD transports the charge across the chip and reads it at one corner of the array.
An analog-to-digital converter (ADC) then turns each pixel's value into a digital value by
measuring the amount of charge at each photosite and converting that measurement to a binary
form.
Each has its own advantages and disadvantages, with price being a major factor in consumer
electronics world.
To conclude : Although numerous differences exist between the two sensors, they both play the
same role in the camera -- they turn light into electricity.
Depending upon the use CCD and CMOS find their different routes. As when they compete in
same field CCD wins over the quality and CMOS over power consumption and architecture.
For cost concerning consumers CMOS is a better choice and as when quality is important CCD
is final choice and ahead of it is FILM.
Advantages of film over CCD or CMOS.
We have seen the CMOS and we have seen the CCD but lets not forget the good old analog camera and
let us see what is the, what are the advantages of film over CCD or CMOS.
First of all film gives better results. there is a smooth flow of the image from one tone to the other tone.
then, the resolution is much higher.
In the case of films, the grain is much finer. which we see in CCD and CMOS.
Then, a film burns out the highlights more gracefully and the quality of a film is preferred over digital.
Let us see the limitations of film.
We can take only one picture per frame.
Then, there are limited number of frames per film.
In case you want to shoot a lot then you will need a lot of films which becomes bulky.
Then for every film ISO is fixed. After you have shot the film detailed processing which is very time
consuming.
Let us compare this with the advantages and disadvantages of digital camera.
First of all we can view the results immediately and in case it is not upto out satisfaction we can delete the
particular frame and we can again shoot.
secondly if we have taken a picture which is not really upto the mark we can modify it in the computer.
for every frame we can modify the we can change the ISO and for low lighting we can increase the ISO
and get a better picture. There is no limitations to the frames in the case of CCD's .
Then the results are stored in a computer where the picture if it has minor defects can be modified . it can
be even altered and made into a creative output. Then, With the CCD's we can shoot both videos as well
as Still pictures.
Let us now see disadvantages of CCD and CMOS.
First of all heat plays a very important part in this and also dust can damage your camera because they are
very sensitive, they are very light and they are prone to damages faster compared to film camera. Film
cameras are more sturdy as compared to digital cameras.
Then another very important factor is that the resolution in the case of the digital camera is lower, much
lower which we see in film and it can not match the film resolution.
We can therefore see that the film dominates over digital. whether it is resolution, color catching ability or
grey spectrum catching ability. the mood set by a film is a lot significant then digital.
although digital technology is trying to compete in higher range section, it still cannot match the films. If
we ignore the hassles of film development no doubt, film is better than digital.
We'll now take up another issue which is printing papers. a very important part. After all a picture that is
taken has to be printed somewhere to be shown every picture need not be on the computer always for
demonstration purposes or for exhibitions we have to put them on to a paper. And therefore the need for
understanding printing papers.
Printing Papers
A major step after the creation and processing of image that the Image is taken over an optimum
hard copy or printing paper In order to give correct look and feel. Printing is a major step after
creating and processing of image. A good paper can give a correct look and feel of the subject.
Printing papers are decided as per the need of the image.
Before understanding different types of papers let us first understand some major properties of
papers.
First of all the weight Basis that is it is on gsm that is to say Grams Sqaure Meter.
The weight or substance per unit area is obviously fundamental in paper and paper borne
products. The basis weight of paper is the weight per unit area. This can be expressed as the
weight in grams per square meter (gsm or g/m2), pounds per 1000 sq. ft. or weight in kgs or
pounds per ream that is of 500 sheets of a specific size.
Ream weight is a common term to signify the weight of a lot or batch of paper. Control of basis
weight is important as all other properties are affected.
Variation of moisture content in paper effects the grammage.
Let us see Brightness, Whiteness and Colour
Brightness is defined as the percentage reflectance of blue light only at a wavelength of 457 nm.
Whiteness refers to the extent that paper diffusely reflects light of all wave lengths throughout
the visible spectrum. Whiteness is an appearance term.
Colour is an aesthetic value. Colour may appear different when viewed under a different light
source.
Brightness is arbitrarily defined but carefully standardized blue reflectance that is used
throughout the pulp and the paper industry for the control of mill processes and certain types of
research and development programmes. Let us see the types of papers and to begin with we have
glossy paper. Glossy paper is most common paper for printing photos. It produces a sharp and
vibrant image. Glossy paper is also smooth to touch.
The disadvantages include the fact it is easy to mark them with fingerprints or dust and they
cannot be removed. Glossy photos are best framed so that no dirt or fingerprints can touch the
image. Glossy paper is also more reflective and shiny which is a problem if you plan to view the
image in sunny area.
If you need your images to be as sharp as possible then you might want to think about using
glossy paper.
Semi gloss is cheaper and more affordable than glossy paper. As the name suggests, it is simply
less glossy. Premium grade is a higher quality paper and will produce sharpest results.
Brand specific papers are produced by companies to be used with their own printers.
Then we have Gloss Laminative, very popular paper.
The best example of a gloss laminated paper is in the form of a postcard. The main photo is on
the front, along with a gloss laminate coat applied, which makes it even shinier. The back has the
texture of plain card stock.
Laminating the paper makes the colours even more vibrant. If you plan to do any sort of
advertising, then glossy laminated paper stands out above others and should be your choice of
paper.
Lets come to another important kind of paper that we use in photography and that is known as
Matte Paper.
Matte Paper looks dull and lusterless. It is used in industry to produce good quality prints but it
doesn’t have a vibrant color finish. Matte paper is not glossy and therefore finger marks or glare
from the sun are not a problem.
A good use of matte paper would be inside a shop in which the lighting might cause reflections.
Due to the non-reflective nature of this paper, it would be ideal.
Disadvantages of matte papers include the fact they soak more ink into the paper, this will affect
the sharpness of the image.
When printing macro shots, portraits or other images, that rely in small details you maybe better
off using a glossy paper. There are many different types of matte papers so pay close attention to
what you purchase a semi matte or luster paper may have totally different look than traditional
matte paper.
Conclusion
Finally in today's programme we saw The CCD, The CMOS that is the digital recording medium
and a film which is old traditional and still better method of medium if recording an image. we
also saw the variety of papers available to us and how they can be used in making a particular
picture to achieve a proper result.