Heeeeerrrrre’s Johnny!
Experienced photographers may be familiar with traditional film-based terms and acronyms, many of which have their origins in the disciplines of optics, chemistry, and physics. The language of digital imaging has its roots in the fields of computing and commercial printing and has shown itself remarkably inventive in creating new buzzwords at the drop of a microchip. Here’s a brief introduction to some of them that digital photographer might find useful.
AF. Autofocus, automatic motorized focusing.
AI FOCUS AF. In cameras such as Canon’s EOS 1D and D60, this is an autofocus mode that automatically switches from One-Shot autofocus to AI-Servo autofocus when a subject moves.
AI SERVO AF. Autofocus mode for moving subjects with focus tracking and shutter priority.
ALIASING. Sometimes when a graphic is displayed on a monitor, you will see jagged edges around some objects. These extra pixels surrounding hard edges—especially diagonal lines—are caused by an effect called aliasing. Techniques that smooth out these “jaggies” are called anti-aliasing.
ANALOG. Information presented in continuous form, corresponding to a representation of the “real world.” A traditional photographic print is an analog form, but when this same image is scanned and converted into digital form, it is made up of bits.
AVERAGE METERING. Through-the-lens (TTL) metering that takes into considera-tion the illumination over the entire image.
BIT. Binary digit. Computers represent all data—including photographs—using numbers or digits that are measured in bits.
BITMAP. A bitmap is a collection of tiny individual dots or pixels—one for every point or dot on a computer screen.
BMP. Often pronounced, “bump,” it’s the file name extension for a Windows-based bitmapped file format.
BYTE. Each electronic signal is 1 bit, but to represent more complex numbers or images, computers combine these signals into larger 9-bit groups called bytes.
CCD. A Charged Coupled Device. This is the kind of light-gathering device used in scanners, digital cameras, and camcorders to convert the light passing through a lens into the electronic equivalent of your original image.
CD-R. Compact Disc Recordable. With these discs, you can write image file data only once, and read it many times.
CD-ROM. Compact Disc Read-Only Memory. A disc that resembles a music compact disk but can hold all kinds of digital information including photographs.
CD-RW. Compact Disk Recordable Writ-able. You can write and read these discs many time but the disks themselves cost more than CD-R’s.
CIELAB. This color system created by the Committee Internationale d’Eclairage to produce a color space consisting of all visible colors. The CIELAB system, sometimes shortened to just LAB, forms the basis for most contemporary color matching systems and lets you convert, for example, RGB images to LAB to CMYK to produce accurate color matching.
CMOS. Complimentary Metal Oxide Semiconductor. An alternative to the CCD (Charged Coupled Device) imaging chips used by some digital cameras. The CMOS chip is simpler to manufacture so costs less. It also uses less power than CCD chips, so it doesn’t drain batteries as fast. The downside is that the chip does not perform as well as CCD imagers under low-light conditions, but recent digital SLR models are said to have improved performance under less than ideal lighting conditions.
CMS. Color Management Systems software helps produce an accurate reproduction of your original color photograph. A good CMS includes calibration and characterization aspects and is (mostly) software based. CMS is used to match the color that you see on your monitor to the color from any output device, such as a printer, so that what you see on the screen is what you get as output. You might think of this as the last step in the WYSIWYG (What You See Is What You Get) process.
CMYK. Cyan, Magenta, Yellow, and Black. For magazine reproduction an image is separated into varying percentages of CMYK, which is why CMYK film output is called separations. Ink-jet printers also use CMYK pigments and dyes to produce photographic quality prints.
COLORSYNC. Apple Computer’s Color-Sync is a Color Management System (CMS) that uses a reference color space based on the way humans see colors. The heart of the system is a set of device profiles that describe what color in that reference space corresponds to the RGB or CMYK values sent to an output device. ColorSync can predict the color you’ll see when you send a set of RGB values to a monitor or CMYK values to a printer and will automatically adjust those values so you’ll see the same color on both devices—or as close as possible within the limits of the devices.
COLOR DEPTH. Sometimes called “bit depth.” Color depth measures the number of bits of information that a pixel can store and ultimately determines how many colors can be displayed at one time on your monitor. Color depth is also used to describe the specifications of devices such as scanners and digital cameras as well as a characteristic of an image file.
COMPRESSION. A method of removing unneeded data to make a file smaller without losing any critical data, or in the case of a photographic file, image quality.
CPU. Central Processing Unit. The CPU powers your computer, although many cameras and lenses too have built-in CPU chips. Digital imagers need to have enough computing power to handle the kind, and especially size, of image they working on. Shooting wildlife or sports photography is possible with a 50-mm lens, but the photographic experience will be much better—and less frustrating—when armed with a 400 or 800-mm lens. Similarly, choosing the right computer is first a matter of finding one with enough power to process digital images fast enough to minimize frustration, and expedite creativity by processing that data as quickly as possible.
CPXe. Common Picture Exchange Envi-ronment. A new standard for distributing photos over the Internet for photofinishing that was created by a consortium of companies including Eastman Kodak, Fujifilm, Hewlett-Packard, and others.
DEVICE RESOLUTION. This refers to the number of dots per inch (see dpi) that a computer device, such as a monitor or printer, can produce.
DVD. Digital Video Disc. Unlike the 600 MB capacity of CD-ROM discs, a DVD can store 4.7GB or more on a single disc that is the same physical size. While competing formats exists for writable DVDs, this has not stooped a number of companies form installing writable DVD drives in computers or offering them as external peripherals. It is just a matter of time, before the DVD format replaces all disc-based data media, including CD-ROM and music CDs too.
DYNAMIC RANGE. Dynamic range can be interpreted as the range of f/stops that can be captured from a print or slide and is rated on a scale from 0 to 4, where 0 is a clean white and 4 is total black. Photographers may recognize these are the zones Ansel Adams called Zones IX and 0 in his Zone System. The maximum and minimum density values of capable of being captured by a specific scanner are sometimes called dMax and dMin. If a scanner’s dMin were 0.3 and its dMax were 3.5, its dynamic range would be 3.2.
EI. Exposure Index is the rating at which a photographer actually exposes a specific kind of film, therefore deliberately underexposing or overexposing it. This is accomplished by changing the camera or hand-held meter’s ISO film speed to reflect a number different than recommended by the manufacturer.
E-TTL. Evaluative Through-the-Lens flash exposure metering used by Canon EOS film and digital cameras.
EV. Exposure Value; numeric value to describe the exposure where a variety of shutter speed/aperture combinations produces the same exposure with a constant film speed; for example 1/250s f/2 1/125s f/2.8 1/60s f/4 1/30s f/5.6 1/15 f/8, etc. (This is different from Exposure Index.)
FAQ. Frequently Asked Questions. A term found on Internet home pages, that lead you to an area containing answers to the most FAQ visitors to the website might have.
FRACTAL. A graphics term originally defined by mathematician Benoit Mandel-brot to describe a category of geometric shapes characterized by an irregularity in shape and design and used by computer software, such as Lizard Tech’s (www.lizardtech.com)Genuine Fractals, as a mathematical model for resizing and enlarging image files.
GAMMA. A measurement of the contrast that affects midtones in an image. One of the differences between Mac OS and Microsoft Windows operating systems is that they have different basic Gamma settings. For a Windows computer it’s 2.2, while Gamma is 1.8 on a Mac OS computer, which is why images that look fine on a Mac appear darker on a Windows computer.
GAMUT. A range of colors that a printer, monitor, or other computer peripheral can accurately reproduce. Every device from every manufacturer has a unique gamut. If you find that the output of your color printer doesn’t match what you see on screen, you are beginning to understand the need for color management. The image may be “in gamut” for the monitor, but not the printer.
GAUSSIAN BLUR. Adobe Photoshop’s filter gets its name from the fact that this filter maps pixel color values according to a Gaussian curve. A Gaussian curve is typically used to represent a normal or statistically probable outcome for a random distribution of events and is often shown as a bell-shaped curve.
GIF. (Pronounced like the peanut butter.) Graphics Interchange Format. A compressed image file format that was originally developed by the CompuServe Information Systems (www.cis.com) and is platform independent. The same bitmapped file created on a Macintosh is readable by a Windows graphics program.
GIGABYTE. A billion bytes or (more correctly) 1024 megabytes.
GRAYSCALE. Refers to a series of gray tones ranging from white to pure black. The more shades or levels of gray, the more accurately an image will look like a full-toned black and white photograph. Most scanners will scan from 16 to 256 gray tones. A grayscale image file is typically one-third the size of a color one.
GUI. Graphic User Interface.
ICC. The International Color Consortium is a group of eight large manufacturers in the computer and digital imaging industries. The consortium works to advance cross-platform color communications, and has established base-level standards and protocols in the form of ICC Profile Format specifications, to build a common foundation for communication of color information.
ICON. Those little “pictures” that represent files and programs that are used by graphical user interfaces (GUI) for operating systems such as the Mac OS or Microsoft Windows.
IDE. Integrated Drive Electronics. Com-puters accepts several kinds of circuit boards to control hard disks, the most common standard was originally called IDE, but the more commonly used current term is ATA (Advanced Technology Attachment).
IEEE. The Institute of Electrical and Elec-tronics Engineers is an organization that’s involved in setting standards for computers and data communications, such as the popular IEEE 1394 aka FireWire aka iLink.
IMAGE EDITING PROGRAM. The broad term for software that allows digital photographs to be manipulated and enhanced to improve and change images much as you would produce similar effects in a traditional darkroom and then some.
IMAGEBASE. Visual database programs that keep track of digital photographs, video clips, graphic files, and even sounds.
INDEXED COLOR. To keep GIF files sizes small, the format’s designers limited the number of colors to 256 and created a palette of those colors that each image using the format draws from. There are two kinds of indexed color images. Those that have a limited number of colors and pseudocolor images. Pseudocolor images are really grayscale images that display variations in gray levels in colors rather than shades of gray, and are typically used for scientific and technical work.
INITIALIZE. The process of setting all values on a hard disk, removable media, or floppy disk to zero; in other words, erasing all of the data that’s currently stored.
INKJET. This kind of printer works by spraying tiny streams of quick-drying ink onto paper to produces high-quality output. Circuits controlled by electrical impulse or heat determine exactly how much ink—and what color—to spray creates a series of dots or lines that form a printed photograph.
INPUT. (verb) (noun) Information entered via keyboard or other peripheral device is called input. Data entered into a computer is said to have been input. A photograph scanned into an image-enhancement program is input into it.
INPUT DEVICE. Any computer peripheral such as a keyboard, memory card reader, or scanner that converts analog data into digital information that can in turn be handled by your computer.
INTEGRATED CIRCUIT. A self-contained electronic device contained in a single semiconductor computer chip.
INTERFACE. The “real world” connection between hardware, software, and users. This is the operating system’s method for directly communicating with you. It’s also any mechanical or electrical link connecting two or more pieces of computer hardware.
INTERLACED. Broadcast television uses an interlaced signal, and the NTSC (National Television Standards Committee) standard is 525 scanning lines, which means the signal refreshes the screen every second line 60 times a second, and then goes back to the top of the screen and refreshes the other set of lines, again at 60 times a second. The average non-interlaced computer monitor refreshes its entire screen at 60–72 times a second, but better ones refresh the screen at higher rates. Anything over 70Hz is considered flicker-free.
INTERNET ADDRESS. The format for addressing a message to any Internet user is [email protected]. The recipient is the person’s name or “handle,” the location is the place where the recipient can be found, and the suffix tells the kind of organization the address belongs to. Locations outside the United States have an additional extension identifying their country.
INTERPOLATED RESOLUTION. Scanners are measured by their optical as well their interpolated resolution. Optical resolution refers to the raw resolution that’s inherently produced by the hardware, while interpolated resolution is software that adds pixels to simulate higher resolution.
IS. Image Stabilization on Canon EOS lenses, called VR (vibration reduction) on Nikon lenses. Konica Minolta, on the other hand, builds its Anti-Shake technology into the camera’s body.
ISO. (1) International Standards Organi-zation. Founded in 1946 with headquarters in Geneva, Switzerland, the ISO sets international standards for many fields. (2) Film speed and equivalents (in digital cameras) are usually referred to by their ISO speed rating that measures light sensitivity. The higher the ISO number, the greater the light sensitivity.
ISP. Internet Service Provide.
JPEG. Joint Photographic Experts Group. JPEG was designed to discard information the eye cannot normally see and uses compression technology that breaks an image into discrete blocks of pixels, which are then divided in half until a compression ratio of from 10:1 to 100:1 is achieved. The greater the compress ratio that’s produced, the greater loss of image quality and sharpness you can expect. Unlike other compression schemes, JPEG is a “lossy” method. By comparison, Lempel-Ziv-Welch (LZW) compression used in file formats such as GIF is lossless—meaning no data is discarded during compression.
K. In the computer world, K stands for two to the 10th power, or 1024. A kilobyte (or KB) is, therefore, not 1000 bytes but is 1024 bytes.
KEYWORD. Words that identify certain characteristics of a photograph for later searching with a photo-organizing, or imagebase program. A good imagebase program should be able to add “keywords” to your photographs, and then be able search for the images that have those words associated with them.
LANDSCAPE (MODE). An image orientation that places a photograph across the wider (horizontal) side of the monitor or printer.
LAYER. In image-enhancement programs, like Adobe Photoshop, layers are any one of several on-screen independent levels for creating separate—but cumulative—effects for an individual photograph. Layers can be manipulated independently and the sum of all the individual effects on each layer make up what you see as the final image.
LZW. Lempel-Ziv-Welch. A compression algorithm used by Adobe Photoshop to perform lossless compression on TIFF files.
MAGNETO-OPTICAL. This class of removable drives uses the ability of lasers to heat material and thus change reflectivity to produce media that can be erased and reused. One of the negatives of optical drives is that writing data to optical media requires three spins. The first erases existing data, the second writes new data, and the third verifies the data is there. When compared to magnetic drives, all this spinning tends to reduce performance. Typical performance specifications for magneto-optical drives are seek times of30ms, access time of 40ms, and average write transfer rate of 0.44/s. The drives are more expensive than magnetic drives—although the media is less so, and like their magnetic competitors, manufacturers have yet to standardize on a single magneto-optical format.
MASK. Many image-enhancement programs have the ability to create masks—or stencils—that are placed over the original image to protect parts of it and allow other sections to be edited or enhanced. Cutouts or openings in the mask make the unmasked portions of the image accessible for manipulation while the mask protects the rest.
MEGABYTE. When you combine 1024 kilobytes, you have a megabyte (MB) or “meg.”
METAFILE. This graphic file type that accommodates both vector and bitmapped data. While more popular in the Windows environment, Apple’s PICT format is a metafile.
MOIRE. (Pronounced “mwah-RAY.”) Moiré patterns are an optical illusion caused by a conflict with the way the dots in an image are scanned and then printed. A single pass scanner is all most people require for scanning an original photograph, but when scanning printed material, a three-pass scan (one each for red, green, and blue) will almost always remove the inevitable moiré or dot pattern.
MTF. Modular Transfer Function curves show how much contrast is retained by a lens in a given image point, for example 0.9 means 90% of the original scene’s contrast was retained.
MULTI-ZONE METERING. Through-the-lens metering where the exposure is measured by several metering cells depending on the subject distance.
NANO. A prefix that means one-billionth.
ND FILTER. Neutral Density filters are rated by how many f-stops they decrease your lens aperture setting. A ND filter let you control an image when the stated combination of film speed, lens aperture, and shutter speeds won’t let you produce the effect you’re attempting to produce.
NTSC. National Television Standards Committee. NTSC sets the standards that apply to television and video playback on resolution, speed, and color. All television sets in the United States (and Japan too) follow the NTSC standard, and videotape and other forms of video display (such as games) meets NTSC standards.
PCX. This is not an acronym and is a bitmapped file format originally developed for the Windows program PC Paintbrush. Most Windows graphics programs read and write PCX files.
PDF. Portable Document Format. A standard file format invented by Adobe Systems that allows people to send graphics files that include text and graphics and can be read exactly as created by the recipient using the free Adobe Acrobat Reader software. You can download-free Mac OS, Windows, and UNIX versions of Acrobat Reader from www.adobe.com.
PHOTO CD. Kodak’s proprietary digitizing process stores photographs onto a CD-ROM disc. The Photo CD process can digitize images from color slides and black and white or color negatives and a Master Disc can store up to 100 high-resolution images from 35-mm film. Images are stored in five different file sizes and five different resolutions.
PICT. Another acronym without a strict definition, this time for a metafile file format for the Mac OS. As a metafile, PICT files contain both bitmapped and vector information.
PICTURE CD. A Kodak process that converts film-based images into digital files, using the JPEG format, and places them photos on a CD-ROM. This service can be ordered when you have your film processed by camera stores and other retail outlets. Their images are returned to consumers as traditional prints and on a Picture CD as digital files that can be viewed, enhanced, printed, or e-mailed.
PIEZOELECTRIC. The property of some crystals that oscillate when subjected to electrical voltage. A form of print head design that is used by Epson in their Stylus Color family of ink-jet printers. On the other hand, piezo-electric (with a hyphen) technology generates electricity when applying mechanical stress.
PIXEL. An acronym for picture element. A computer’s screen is made up of thousands of these colored dots of light that, when combined, produce a photographic image. A digital photograph’s resolution, or visual quality, is measured by the width and height of the image measured in pixels.
PMT. Photomultiplier Tubes are a type of sensing technology used in drum scanners.
PNG. (Pronounced “ping.”) Portable Net-work Graphics. This successor to the GIF format created by a coalition of independent graphics developers to design a new royalty-free graphics file format. Not many people use it, though.
POSTSCRIPT. A programming language created by Adobe Systems that defines all of the shapes in a file as outlines and interprets these outlines by mathematical formulae called Bezier curves. Any PostScript-compatible output device uses those definitions to reproduce the image on your computer screen.
PPI. Pixels per inch.
PROFILE. A small file that tell your monitor (or any other device) that associates each number with a measured color based on specifications created by the International Color Consortium (www.icc.org). When you computer communicates color information it not only transmits numerical data, but also specifies how those numbers should appear. Colormanaged software (the next step) can then take this profile into consideration and adjust the device accordingly.
RAM. Random Access Memory. RAM is that part of your computer that temporarily stores all data while you are working on an image or a letter to Granny. Unlike data stored on a hard drive this data is volatile. If you lose power or turn off your computer, the information disappears. Most computer motherboards feature several raised metal and plastic slots that hold RAM chip in the form of DIMMs (Double Inline Memory Modules.) The more RAM you have the better it is for digital imaging work, there are economic considerations too. As I write this RAM, is inexpensive, but prices can be volatile.
RESOLUTION. A digital photograph’s resolution, or image quality, is measured by an image’s width and height as measured in pixels. When a slide or negative is converted from silver grain into pixels the resulting digital image can be made at different resolutions. The higher the resolution of an image—the more pixels it has—the better the visual quality. An image with a resolution of 2048 3072 pixels has better resolution and more photographic quality than the same image digitized at 128 192 pixels.
RGB. Red, Green, and Blue. Color monitors use red, blue, and green signals to produce all of the colors that you see on the screen. The concept is built around how these three colors of light blend together to produce all visible colors.
RIP. Raster Image Processor. RIP is a process that prepares image data for the screen or printer.
ROM. Read-Only Memory is that memory in your computer that you can only read data from. It’s a one-way street.
SATURATION. Saturation, often referred to as Chroma, is a measurement of the amount of gray present in a color.
SEARCH ENGINE. Since the actual number of websites on the World Wide Web is big and getting bigger everyday, finding the Exacta Collectors home page (www.ihagee.org)might be impossible without a way to search for the word “Exacta.” That’s the function of search engines: you type in a word or words and a list of websites whose descriptions contain those keywords appear.
SELECTION TOOL. One of the most important tools found in an image-enhancement program are selection tools. These allow you to highlight or select portions of an image that will have an effect applied to them.
SERIAL PORT. An outlet on the back of a computer used to connect peripheral devices such as modems and printers. The serial port sends and receives data one bit at a time.
SHAREWARE. Shareware is a creative way of distributing software that lets you try a program for up to 30 days before you’re expected to pay for it.
SLR. Single Lens Reflex. In an SLR camera, the image created by the lens is transmitted to the viewfinder via a mirror and the viewfinder image corresponds to the actual image area.
THUMBNAIL. This is an old design industry term for “small sketch.” In the world of digital photography, thumbnails are small, low-resolution versions of your original image.
TIFF. Tagged Image File Format is a bitmapped file format that can be any resolution and includes black and white or color images. TIFFs are supposed to be platform-independent files so files created on your Macintosh can (almost) always be read by any Windows graphics program.
TRANSFER RATE. A measurement of the average number of bytes per unit of time passing between disk storage and processor storage.
TTL. Through-the-Lens. In this system, the camera measures the actual light entering the lens.
TWAIN. Not an acronym, although some pundits insist it stands for “Technology Without An Interesting Name.” A hardware/software standard that allows users to access scanners and other hardware peripherals from inside Windows applications, although the TWAIN standard can be found on Mac OS computers too.
UNDO. One of the most useful tools, commands and/or features an image-enhancement program can have; it lets you go back to the way the image was before you made the last change.
UNIX. A multi-user, multi-tasking (doing more than one thing at the same time), multiplatform operating system originally developed by Bell Labs for mainframe and minicomputers back in the bad old days of computing.
UNSHARP MASK. In Adobe Photoshop, and other image-editing programs, this is a digital implementation of a traditional darkroom technique where a blurred film negative is combined with the original to highlight the photograph’s edges. In digital form, it’s a controllable method for sharpening an image.
URL. Uniform Resource Locator. That’s how you find a website (www.joefaraceshootscars.com, e.g.) when using an Internet browser software.
VARIATIONS. A command found in Adobe Photoshop that gives you control over the hue and color intensity of an image.
VECTOR. Images saved in this format are stored as points, lines, and mathe-matical formulae that describe the shapes making up that image. When vector files are viewed on your computer screen or printed, the formulae are converted into a dot or pixel pattern. Since these pixels are not part of the file itself, the image can be resized without losing any quality.
VIRTUAL MEMORY. Sometimes called (by Adobe in Photoshop) a “scratch disk.” When not enough “real” memory is available, this process borrows a chunk of your hard disk to store data and perform imaging calculations.
VRAM. Video Random Access Memory.
WMF. Windows Metafile Format. A vector graphics format designed to be portable from one PC-based program to another.
WORM. (1) Write Once Read Many times and (2) a form of computer virus that continually duplicates itself on your hard disk, gradually using all of your computer’s resources before ultimately shutting it down.
WYSIWYG. (Pronounced “wissy-wig.”) What You See Is What You Get. This term refers to the ability to view text and graphics on screen in the same way, as they will appear when printed.
XAOS TOOLS. (Pronounced “chaos.”) A software company that offers several packages of Adobe Photoshop-compatible plug-ins that can produce artistic-looking images.
YCC. The color model used by Kodak in its Photo CD process. This involves the translation of data that was originally in RGB form into one part of what scientists call “luminance” but the rest of us call brightness—this is the Y component. The format includes two parts—the CC—of chrominance or color and hue.
ZIP. Iomega’s Zip removable media drive that has a cartridge that looks like a fat floppy disk and uses a combination of conventional hard disk read/write heads with flexible disks. Zip disks are available in two capacities: 100 and 250MB.
ZOOM. A tool found in most image-enhancement program that lets you zoom into any photograph by clicking your mouse button. The Zoom is tool depicted by a magnifying glass icon so often that it’s often just called “magnifying glass.”