Understanding Digital Cameras, Scanners, and Image Formats
Digital Camera Components and Features
CCD Photosensor
The CCD photosensor is the digital camera component responsible for transforming light into electrical signals.
Key Characteristics of Digital Cameras
Resolution
Resolution describes the level of detail in an image. A 6-megapixel sensor is often considered a good balance between megapixels and image quality for compact cameras.
Optical Zoom
Optical zoom adjusts the camera’s focal length to bring the subject closer. A 4x zoom is a common value.
Screen Size
Screen size refers to the usable area on the monitor’s screen, typically around 2.5 inches.
Energy
Digital cameras are powered by batteries, often lithium-ion batteries.
Types of Digital Cameras
Compact Cameras
Simple cameras with non-removable lenses.
Reflex Cameras
Cameras where the photographer sees the exact image that will be captured.
Bridge Cameras
Cameras that combine features of both compact and reflex cameras.
Scanners: Functionality and Features
Scanners use a glass surface to hold the document while a scanning arm moves underneath. The arm contains a light source and photosensor.
Multifunction Devices
Multifunction devices combine a printer, scanner, and photocopier.
Key Characteristics of Scanners
Color Depth (bits)
A common color depth is 48 bits.
Resolution (dpi)
A common resolution is 2400 x 4800 dpi.
Connection (Port)
USB 2.0 is a common connection port.
OCR (Optical Character Recognition)
OCR programs convert handwritten text documents into digital text.
Pixel Interpolation
Pixel interpolation increases the size of an image by filling in missing information using algorithms.
Storage: Memory Cards
CompactFlash
Originally a data storage device used in portable electronic devices.
Micro Drive
Data storage technology based on a 1″ hard disk.
Memory Stick
A Sony electronic card that can be attached to a PCMCIA card.
Multimedia MMC
A type of memory card found in many electronic devices, including digital cameras.
Secure Digital (SD)
A flash memory card format used in portable devices like digital cameras, mobile phones, and game consoles.
Smart Media
A flash memory card standard developed by Toshiba in 1995.
XD Picture Card
A proprietary flash memory card used by Olympus and Fujifilm for their digital cameras.
Characteristics of a Digital Image
Color Depth
The number of bits needed to represent the color of a pixel in a digital image, measured in bits.
Image Resolution
The level of detail in an image, measured in pixels.
Image Size
The real dimensions of an image when printed, measured in pixels wide by pixels high (e.g., 1024×720).
Image File Types
File Formats for Digital Cameras
- JPEG
- TIFF
- PNG
- RAW
Features of Common Image Formats
JPEG
A compressed format that reduces file size by sacrificing some image quality.
TIFF
Usually stored uncompressed or using lossless compression algorithms.
PNG
An image format developed to replace older image formats.
RAW
A format that saves images with minimal processing, often used in high-end cameras. It is not a standard image format.
Raster Image
A data file represented by colored dots or pixels displayed on a computer monitor, paper, or other device.