‘A’ size or ‘A’ series paper sizes: set of paper sizes established by the International Standards Organization (ISO) that ranges from 2A0 (the largest) to A7 (the smallest). The size of the paper goes down as the number goes up, and each is half the size of the previous i.e. two A4 sheets make up an A3 piece and two A5 sheets make up an A4 sheet. North America has a different, local standard.
Aperture: the size of the opening of the camera's shutter. Aperture sizes are reported in F-numbers which are inversely proportional to the aperture size, so a 5.6 aperture setting is smaller than a 4 aperture setting. Aperture, along with shutter speed and ISO setting, determines the image's effective exposure by determining the amount of light that reaches the camera's sensor and the sensitivity of the sensor to the light. Some point and shoot cameras only have a minimal real aperture setting and instead fake a higher f-number by filtering out some of the incoming light. Aperture settings around 5.6 tend to result in pictures with the greatest sharpness.
Auto feed scanner: a type of scanner that uses ADF (Automatic Document Feeder) to scan loose unaided pages and documents. Also called sheet feed scanner.
Automatic document feeder: it's a method to scan loose papers. It can be added as a feature of a flatbed scanner or be an ADF scanner standalone.
Base: a part of the book scanner, which holds the rest of the structure.
Bitonal: a 1-bit image, with a foreground colour and a background color (normally, black and white). It's usually confused with 'grayscale', but actually grayscale is an 8-bit image.
Bit depth: number of bits used to indicate the color of a single pixel or the number of bits used for each color component of a single pixel. See Color Depth.
Book Scan Wizard: a free software for postprocessing the pictures taken with a bookscanner. Read more about the project in SourceForge or in the DIY Book Scanner forum.
Book scanning: the process of converting physical books and magazines into digital media, by using an image scanner.
Bridge camera: a type of digital camera with usually better sensors and lenses than a compact point and shoot camera, but with a single lens that cannot be changed. They often have a wide zoom range however and may also be called super-zoom, ultra-zoom or similar. Read more.
Candela: the base unit to measure luminous intensity, i.e., the power emitted by a light source in a particular direction.
CHDK: stands for "Canon Hack Development Kit". A replacement firmware for many Canon cameras that allow to expand the configuration options of the camera, as well as scripting and adding an external shutter release for those cameras that don't have it. This is not an official feature of Canon. Read more.
CNC router: a computer controlled machine, that automatically cut parts out of several materials (wood, steel, plastic, amongst others), after putting design files into it.
Color depth: the number of bits used to indicate the color of a single pixel.
Color Rendering Index (CRI): a quantitative measure of the ability of a light source to reveal the colors of various objects faithfully in comparison with an ideal or natural light source.
Command Line Interface (CLI): a way to interact with the computer, sending orders to it in the form of text lines.
Compact Fluorescent Lamp (CFL): a fluorescent lamp designed to replace an incandescent lamp. It's a low-energy light-bulb.
compression, Lossless: a method that uses data compression algorithms that allow the resulting file to be compressed preserving the bits that were used to represent the image and without losing data in the middle.
compression, Lossy: a method for representing the content that has been encoded, that uses inexact approximations and therefore has data lost in the middle. The resulting file after applying a lossy compression process has less bits than the uncompressed file, but poor quality in comparison with the original file.
Cradle: a part of the book scanner. It's where you put the book in order to keep it open while scanning.
Deskewing: to rotate a scanned image to compensate for skewing, and straighten the text.
Destructive scanning: a method to scan books which consist in taking the bindings away (normally with a saw) to feed the pages into an auto feed scanner. Not recommended for libraries or preservation purposes. Read more on the DIY Book Scanner forum.
Dewarp: to straighten or to undo the effects of image warping, which can be caused by optical aberration or by digital manipulation. In DIY Book Scanning, "dewarping" refers to the action of flattening the images of the pages of a book with software, so it looks like a flat page instead of a curved page. See also optical aberration.
E-book: an electronic book, or a book published in digital format.
E-reader: a mobile device designed to read e-books and other digital media.
EPUB: free and open book standard for Electronic PUBlication.
Exposure: the amount of light that the image sensor captures and stores as the picture. Higher exposures can wash a picture out to the white end of the spectrum, called over-exposure, while lower exposures can lose color and under-expose. Aperture, shutter speed, and ISO (named as the "exposure triangle") are the settings that determine the exposure.
White Balance: The setting on a camera to set the light type. Different types of light make a big difference on the final color of a scans. Cameras have settings like "tungsten" "cloudy", "daylight" or manual. The goal of setting the white balance is to make the resulting colors accurate.
