21 Sep 08 The Technology Behind Digital Cameras
Author: Roberto Sedycias
Technology has revolutionized the concept of capturing live images. The earlier concept of producing permanent photograph was based on pure chemistry. In 1830, Louis Daguerre, devised the first practical way of producing permanent photographs. Today we are talking about the computerized photo imagery in the filmless picture taken by a device that is smart in electronic intelligence and in appearance - digital camera.
A digital camera takes video, still photographs, or both digitally. It records images on a light sensitive sensor. Instead of using a film, an arrangement of charged-coupled devices-light sensitive semiconductors, which stores electrical charges,-does the job. These digital sensors-composed of pixels -transform the light from the scene snapped into an analog signal which is then converted into a digital version. One electronic filtering system regulates color and other picture components. Another system reduces the picture. The image is finally sent to a temporary storage area and ultimately onto a memory card. Many compact digital cameras can record sound, video and still photographs.
The images are transferred to a computer where they can be modified, printed, attached to email, inserted in web pages, etc. The most significant advantages of a digital camera are its memory capacity and ability to screen the images taken on a tiny video monitor.
The technology of the digital camera relates to the same technology of Video Tape Recorder. The first VTR in 1951 captured images from the television by converting the information into electrical impulses (digital) and subsequently saving them onto magnetic tape. It was in 1960s when NASA had made a major breakthrough by converting analog to digital signals by means of the space probe for mapping the surface of the moon. Also digital imaging had its other uses in spy satellites.
Kodak scientists invented the first mega pixel sensor capable of recording 1.4 million pixels. In 1991, Kodak released the first digital camera system- a Nikon F-3 camera equipped with 1.3 megapixels aimed at journalists. The first digital camera for the consumers which worked with a home PC via a serial cable were the Apple Quick Take 100 camera(1994), the Kodak DC40 camera(1995), the Casio QV-11 with LCD monitor(late 1995) and Sony`s Cyber-Shot Digital Still Camera(1996).
The main features of a digital camera can be summarized as follows:
Resolution: Resolution means sharpness of a picture. The higher the number of pixels, the higher is the resolution.
Memory: The pictures are stored like a data file in a digital camera. The size of the memory determines the number of picture which can be taken, stored and downloaded in the computer.
Flash Type: Most digital cameras have a built in flash of a range around 10 -16 feet which is required to provide extra light needed to take photographs in insufficient light.
Optical Zoom: Normally two types of zoom lenses are used viz., digital and optical. The optical zoom lenses serve more purpose like adding detail and sharpness.
Compression: This process helps to reduce the file size.
Lens: The length of a lens determines how much of a scene will fit into a picture.
LCD Screen: A very interesting feature of a digital camera is the LCD screen which permits one to see what the photo will look like before and after taking photographs, leaving room to decide whether to erase or save the photo.
In the market there are several brands of digital camera which are selling successfully and the continuous improvement in Technology is leading way to introduction of more and more exciting features in the digital camera.
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20 Sep 08 The Magic Behind Digital Camera
Author: Harry Rockwell
A digital camera, as opposed to a film or videotape camera, uses an electronic sensor to transform images (or video) into electronic data. Modern digital cameras are typically multifunctional and the same device can take photographs, video, and/or sound.
In 2005, digital cameras are starting to push traditional film cameras out of many markets. Shrinking device sizes have recently allowed miniaturized digital cameras to be included in multifunctional devices, such as cell phones and PDAs.
Classification
Digital cameras can be classified into several groups:
* Professional video cameras such as those used in television and movie production. These typically have multiple images sensors (one per color) to enhance resolution and color gamut. Professional video cameras usually do not have a built-in VCR or microphone.
* Camcorders used by amateurs. These are a combination of camera and VCR to create an all-in-one production unit. They generally include a microphone to record sound, and feature a small LCD to watch the video during filming and playback.
Still cameras
Digital still cameras are generally characterized by the use of flash memory and USB or Fire Wire for storage and transfer.
Most have a rear LCD for reviewing photographs. They are rated in mega pixels; that is, the product of their maximum resolution dimensions. The actual transfers to a host computer are commonly carried out using the USB mass storage device class (so that the camera appear as a drive) or using the Picture Transfer Protocol and its derivatives.
All use a CCD (for Charged Coupled Device) which is a chip comprised of a grid of phototransistors to sense the light intensities across the plane of focus of the camera lens.
There has recently been some application of a second kind of chip, called a CMOS (Complementary Metal-Oxide Semiconductor) sensor, and this chip is often differentiated from a CCD proper in that it uses less power and a different kind of light sensing material, however the differences are highly technical and many manufacturers still consider the CMOS chip a charged coupled device. For our purposes, a chip sensor is a CCD.
* Standard Digital Cameras: This encompasses most digital cameras. They are characterized by great ease in operation and easy focusing; this design allows for limited motion picture capability. They have an extended depth of field.
This allows objects at multiple depths to be in focus simultaneously, which accounts for much of their ease of focusing. It is also part of the reason professional photographers find their images flat or artificial-looking. They excel in landscape photography and casual use.
* Digital SLRs typically have a sensor nine times larger than that of a standard digital camera, and are targeted at professional photographers and enthusiasts. They resemble ordinary professional cameras in most ways, with replaceable flash and lens components, which give the user maximum control over light, focus and depth of field.
They are also bulkier and more expensive than their casual-use oriented counterparts. They are superb for portraiture and artistic photography because they can be customized for various applications with a comprehensive range of exchangeable lenses.
Professional modular digital camera systems
High-end digital camera backs used by professionals are usually separate devices from the camera bodies which they are used with. (This is because most of the large- and medium-format camera systems in professional use at the time that digital capture overtook film as the professional’s medium of choice were modular in nature, i.e. the camera body had multiple lenses, viewfinders, winders and backs available for use with it to fit different needs.)
Since the first backs were introduced there have been three main methods of “capturing” the image, each based on the hardware configuration of the particular back.
The first method is often called “Single Shot,” in reference to the number of times the camera’s sensor is exposed to the light passing through the camera lens.
Single Shot capture systems use either one CCD with a Bayer filter stamped onto it or three separate CCDs (one each for the primary additive colors Red, Green and Blue) which are exposed to the same image via a beam splitter.
The second method is referred to as “Multi-Shot” because the sensor is exposed to the image in a sequence of three or more openings of the lens aperture. There are several methods of application of the multi-shot technique.
The most common originally was to use a single CCD with three filters (once again red, green and blue) passed in front of the sensor in sequence to obtain the additive color information.
Another multiple shot method utilized a single CCD with a Bayer filter but actually moved the physical location of the sensor chip on the focus plane of the lens to “stitch” together a higher resolution image than the CCD would allow otherwise. A third version combined the two methods without stamping a Bayer filter onto the chip.
The third method is called “Scan” because the sensor moves across the focus plane much like the sensor of a desktop scanner.
These CCDs are usually referred to as “sticks” rather than “chips” because they utilize only a single row of pixels (more properly “photosites”) which are again “stamped” with the Bayer filter.
The choice of method for a given capture is of course determined largely by the subject matter. It is usually inappropriate to attempt to capture a subject which moves (like people or objects in motion) with anything but a single shot system.
However, the higher color fidelity and larger file sizes and resolutions available with multi-shot and scan-backs make them attractive for commercial photographers working with stationary subjects and large-format photographs.
Webcams
* Webcams are digital cameras attached to computers, used for video conferencing or other purposes. Webcams can capture full-motion video as well, and some models include microphones or zoom ability.
These devices range in price from very inexpensive to expensive higher-end models; many complex webcams have a servo-controlled base capable of tracking facial motion with the help of software.
Interpolation
Image color or resolution interpolation is used unless the camera uses a beam splitter single-shot approach, three-filter multi-shot approach, or Foveon X3 sensor.
The software specific to the camera interprets the information from the sensor to obtain a full color image. This is because in digital images, each pixel must have three values for luminous intensity, one each for the red, green, and blue channels. A normal sensor element cannot simultaneously record these three values.
The Bayer filter pattern is typically used. A Bayer filter pattern is a 2×2 pattern of light filters, with green ones at opposite corners and red and blue elsewhere.
The high proportion of green takes advantage of properties of the human visual system, which is determines brightness mostly from green and is far more sensitive to brightness than to hue or saturation.
Sometimes a 4-color filter pattern is used, often involving 2 different hues of green. This provides a wider color gamut, but requires a slightly more complicated interpolation process.
The luminous intensity color values not captured for each pixel can be interpolated (or guessed at) from the values of adjacent pixels which represent the color being calculated.
In some cases, extra resolution is interpolated into the image by shifting photosites off of a standard grid pattern so that photosites are adjacent to each other at 45 degree angles, and all three values are interpolated for “virtual” photosites which fall into the spaces at 90 degree angles from the actual photosites.
Connectivity
Many digital cameras can connect directly to a computer to transfer data. USB is the most widely used method, though some have a Fire wire port.
Integration
Some devices, like mobile phones integrates digital cameras. Mobile phone cameras are much more sold than standalone digital ones.
Digital cameras need memory to store data. The higher one goes in pixel size, the more memory will be needed. Cameras use a removable memory card to store data, but the cheapest and smallest cameras may simply use fixed internal memory instead. Some cameras come with inbuilt memory as well.
Autonomous devices
An autonomous device, such as a PictBridge printer, operates without need of a computer. The camera connects to the printer, which then downloads and prints its images. Some DVD recorders and television sets can read memory cards too.
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19 Sep 08 Digital Camera Basic Information
Author: Roberto Sedycias
A digital camera is an electronic gadget that can capture photographs and then store them. Instead of employing photographic films like the traditional cameras or using magnetic tapes to record images in an analog format like in video cameras, a digital camera stores photographs in an electronic way in a digital format. Nowadays we also get modern and multifunctional compact digital cameras that can record and store sound and video apart from pictures.
Digital cameras have become a rage everywhere in the world. They are amongst the top items of must-have lists of every home. Not only much more technically advanced with better features than their older versions, digital cameras are also very handy and practical. They come in a wide range and variety to suit everyone`s tastes and budget.
Apart from having a better picture quality, the most obvious advantage of digital cameras over the conventional ones is that you can click and store as many pictures as you want without worrying about wasting the film roll. After you have transferred the pictures to your computer, you can easily keep those you want, discard others, print some and may even edit the not so flattering ones. This clearly gives you a lot of options and choices as you can change the background of photograph edit brightness and contrast and make other changes according to your whims.
Digital cameras can be of various types. The first in the category is the video camera which is mainly used to record moving images. Then you have digital still camera or live preview cameras. These cameras are usually of two types, compact and bridge. Compact digital camera has small zooms and is characterized by easy focusing and easy operation. They usually have a built in flash. Bridge digital cameras have super zoom lenses and are capable of taking good images.
Then we have digital single lens reflex cameras with a mirror and reflex system, digital rangefinders which is nothing but a camera that has a rangefinder and the professional modular digital camera system that is a very professional camera with different modular parts like grips, winders etc to suit different purposes. These types of cameras are usually used for commercial purposes in studios as they are quite big and bulky.
With a wide variety of digital cameras available in the market, it is obvious to get confused as to which will be the best-buy amongst them. However you need to understand that each camera has its unique function and specialty and you need to check out each one to determine your pick. As for example, if your purchased camera is going to be a gift then you need to know which type of digital camera will be suitable for the person. For instance, teens will obviously like cameras that are funky and cool, while mums will be delighted to get cameras that will allow easy image sharing for family pictures.
Before buying a digital camera it is important that you get your basic information right so that you can get the best deal. There are lots of factors that you need to consider like the resolution of the photograph and the size of camera. Another important consideration is the Digital Camera Storage or Memory Cards. Semi-professional photographers would also like to consider having a decent Digital Camera Zoom.
Last but not the least, after you get your brand new digital camera then learn about the basics of its maintenance and operation. Get acquainted with its various features; learn how to share your images with friends and family and steps to take to troubleshoot your camera.
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18 Sep 08 Digital Camera: a Buyers’ Guide
Author: Russ Snapper
A digital camera takes still photographs or videos or both by recording the images on a light-sensitive sensor digitally. Most compact digital still cameras can record moving video and sound as well, apart from still photographs. The sales and popularity of digital cameras have increased now compared to the 35mm film cameras.
Digital cameras have a feature for viewing the image that is recorded immediately on the Camera display screen, the feature that is not available in film cameras. Other features include such as the facility to capture a lot of images on a small memory chip, record video along with sound, edit the images, delete the images not required etc. Digital cameras are now available along with many devices ranging from mobile phones and PDAs to vehicles.
The camera perhaps has been affected more by the digital technology than any other products. The digital cameras are not a new phenomenon. The first digital camera was released by Kodak in the U.S. market around 15 years ago. The DCS-100 model at that time with 1.3-mega pixels was available for about $13,000. The digital cameras have emerged with more features and are available at comparatively lesser prices, even to the extent of $80 at select stores.
The biggest benefit of Digital camera technology is the storage capability. You can view the photos on the camera itself, on a web page, a computer monitor, or on paper after printing. The digital camera can be connected to the printer directly through the USB port for printing pictures. People can afford to buy a digital camera today as the prices have fallen with the availability of more features.
It is important for you to know the issues of image resolution for comparing digital camera models. The unit of graphical representation used for displaying digital data by Digital cameras is called Mega Pixel (MP). More the mega pixels, the higher the resolution of the final image. Still you need to compare digital camera images recorded with your actual requirements.
Some typical resolutions found on Digital cameras are:
256×256 – This is available with very cheap cameras. Picture quality is unacceptable.
640×480 – Suitable for posting pictures over a web site or for sending pictures by email.
1216×912 – This resolution is good for printing pictures.
1600×1200 – This is a High resolution standard with around 2 million total pixels.
2240×1680 – This is available on most 4 mega pixel cameras.
4064×2704 – This is available on high-end digital camera with 11.1 mega pixels.
Some High-end consumer cameras can record pictures of over 12 million pixels. Most professional cameras have 16 million pixels. Large format cameras have 20 million pixels. For comparison sake, it is stated that the quality of 35mm film is approximately around 20 million pixels. Some types of Digital cameras are Point and Shoot, Semi-Professional, Bridge and SLR.
You need to know the complete package offered when you compare the prices of digital cameras. You can look for the availability of image-editing software, carry case, add-on Memory card and USB cable for working on your computer, when you want to compare the prices and the features offered. Other general features that you can look into are the availability of an LCD screen, a timer, a built-in flash, a date & time stamp, optical zoom feature and optical zoom lenses of good quality.
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