Part 2. Image Capture

Image Capture

There are several main ways to capture an image, the main examples of these being a scanner, digital camera, or tablet. A scanner is a device that optically scans images, printed text, handwriting or an object, and converts it into a digital image. A digital camera is different to this, the camera captures images electronically rather than on film. The image is captured by an array of CCDs (charge coupled devices), stored within the camera’s random access memory (RAM). Lastly the tablet is a device that is imputed into the computer to hand draw images and graphics, similar to the ways it is drawn with a pencil and paper. These tablets may also be used to capture the data of a handwritten signature.

Scanners

Scanners are a vital part of capturing images. The process of scanning is to analyse the image and process it. Image and text can be captured sing a scanner and imported onto a computer where it can be edited or enhanced. From there the image which is scanned can be printed or placed on a web page for further use. There are different types of scanners which all have distinct uses.

Flatbed scanners are also called desktop scanners, these scanners are the most commonly used scanners in office and work places and are generally used to scan images or text which is on paper.

Sheet-fed Scanners are scanners that are somewhat similar to flatbed scanners, these scanners allow the document to be moved and the scan head is fixed in position to scan the moving document.

Handheld Scanners have the same basic technology uses as that of the flatbed scanner, however rely on the user to move the scanning head instead of motors that do it for you. These aren’t good at making sharp images, however are good for making quick scans of text.

The Drum scanner is greatly used by the publishing industry to capture detailed imagery. The technology drum scanners use is called a photomultiplier tube or PMY for short. The PMT, uses a glass cylinder, that the document is mounted on, which has a sensor that will splits light into three beams into the document. Each beam is sent through a colour filter into the photomultiplier tube where the light is changed into an electric signal.

Digital Cameras

Digital cameras are another vital part of capturing images, digital cameras can capture images that scanners cannot. To view an image taken on a camera, on a digital device, you can either use a conventional film camera. by processing the film chemically, then use a digital scanner to scan the image to view on a digital device or another way, is to take the photo using a digital camera and use a connectable cord which can connect via the USB port, or importing the memory card directly into the computer.

Within digital cameras there is a sensor that converts light into electronic charges. The image sensor used by most digital cameras is the charge coupled device (CCD), however some cameras use a complementary metal oxide semiconductor (CMOS) technology. Both CCD and CMOS convert light into electrons.

The sensor then reads the accumulated charge value of each cell within the image; the CCD transports the charge across the chip and reads it at one corner of the array. Then as analog-to-digital converter (ADC) then turns the pixel’s values into digital values. However CMOS devices use several transistors at each pixel to amplify and move the charge using wires.

CCD sensors create high-quality photos, with low noise, whereas CMOS sensors are more susceptible to noise.

Tablets

Compared with cameras and scanners, the tablet is used and works in an entirely different way. A tablet, otherwise graphics pad, woks like a pen and paper, the tablet is built with a pressure sensor that comes with a special pen to transfer whatever is drawn on the tablet to the computer or digital device you are using.

Tablets are used in conjunction with programs like Photoshop, Painter Pro. Etc. for drawing and creating graphic images, many famous digital artists use tablets to draw on the digital device.
The Tablet can be combined with the use of scanners and cameras. The Tablet and pen can be used to edit the pictures taken on the camera, or scanned in with the scanner.