Adjustment Layer:
In Adobe Photoshop, Adjustment layers allow a user to set color and tonal adjustments to an image without permanently modifying the pixels in the image. The color and tonal changes reside within the adjustment layer, which acts as a veil through which the underlying image layers appear. An adjustment layer affects all the layers below it allowing you to correct multiple layers by making a single adjustment, rather than making the adjustment to each layer separately.
Algorithm:
A mathematical process that solves a problem or equation in a step-by-step manner with a specific beginning and end. In digital imaging, the term is often used to describe the process used for image compression and color management programs.
Banding:
Small equally spaced lines that run through a print.
Bit Depth:
(8 bit/16/bit)
Also called pixel depth or color depth, measures how much color information is available to display or print each pixel in an image. Greater bit depth (more bits of information per pixel) means more available colors and more accurate color representation in the digital image.In most cases, Lab, RGB, Grayscale, and CMYK images contain 8 bits of data per color channel, Adobe Photoshop can also read and import Lab, RGB, CMYK, and Grayscale images that contain 16 bits of data per color channel.
Black Point Compensation:
The, Use Black Point Compensation, option in Adobe Photoshop controls whether to adjust for differences in black points when converting colors between color spaces. When this option is selected, the full dynamic range of the source space is mapped into the full dynamic range of the destination space. When deselected, the dynamic range of the source space is simulated in the destination space; although this mode can result in blocked or gray shadows, it can be useful when the black point of the source space is darker than that of the destination space.
The, Use Black Point Compensation, option is selected for all predefined configurations in the Settings menu of the Color Settings dialog box. It is highly recommended that this option is selected.
Burn & Dodge:
Technique for regulating exposure on specific areas of an analog photographic print. The technician holds back light to lighten an area on the print (dodging) or increase the exposure to darken areas on a print (burning). The same effect can be recreated digitally using Adobe Photoshop's burn and dodge tools.
Calibration:
The setting of computer system components to a standard that will produce the same readable results on each unit, i.e., color calibration is necessary on the monitor to achieve the same results on a print.
CMYK:
Abbreviation for Cyan Magenta Yellow Black. (K is used instead of B to avoid confusion with blue.) A subtractive color space and printing process that reproduces colors by combining, cyan, magenta, yellow, and black inks. This process is referred to as four-color printing, CMYK printing, or process printing.
Channel:
Color information channels are created automatically when opening a new image - and the image's color mode determines the number of color channels created. For example, an RGB image has four default channels: one for each of the red, green, and blue colors plus a composite channel used for editing the image.
Alpha channels are used to create and store masks, which allow a user to manipulate, isolate, and protect specific parts of an image.
In Adobe Photoshop, the Channels palette allows a user to create and manage channels and monitor the effects of editing. The palette lists all channels in the image - composite channel first (for RGB, CMYK, and Lab images), then individual color channels, spot color channels, and finally alpha channels. A thumbnail of the channel's contents appears to the left of the channel name; the thumbnail automatically updates during edits.
Color Balancing:
The act of adjusting colors in an image to match the original scene or visual intent.
Color Cast:
A tint or hue that evenly covers an entire image.
Color Curves:
A mechanism for controlling color changes and matching colors. Color curves are set by user-adjustable lookup tables that define a color transform, which may be applied to each primary additive or subtractive color in the image.
Color Management:
A system of controlling digital data between all imaging devices from capture, to monitors to printers that ensures accuracy and repeatable.
Color Space:
The type of color environment one is working in, be it additive (RGB), subtractive (CMYK) or special colors. In Adobe Photoshop Color Space refers to the working space which produces a certain range or gamut of colors i.e. Adobe RGB 1998, Colormatch etc.
Contrast:
The difference between the darkest and lightest areas in an image. The greater the difference, the higher the contrast.
Curves:
A series of points that are used to modify and manipulate the ratio, or relationship, between shades of grey or shades of color tone.Within Adobe Photoshop, like the Levels dialog box, the Curves dialog box allows one to adjust the entire tonal range of an image. But instead of making adjustments using only three variables (highlights, shadows, midtones), with Curves one can adjust any point along a 0-255 scale while keeping up to 15 other values constant. Curves can also be used to make precise adjustments to individual color channels in an image.
Desaturate:
To reduce all color in an image to shades of gray. In Adobe Photoshop, the Desaturate command converts a color image to a grayscale image in the same color mode. For example, it assigns equal red, green, and blue values to each pixel in an RGB image to make it appear grayscale. The lightness value of each pixel does not change.
This command has the same effect as setting Saturation to -100 in the Hue/Saturation dialog box.
Dither:
A random pattern added to the dots in a screening pattern to hide artifacts like banding or moir? patterns.
Within Photoshop, dithering refers to the method of simulating colors not available in the color display system of the computer. Images with primarily solid colors may work well with no dither. Images with continuous-tone color (especially color gradients) may require dithering to prevent banding.
D-MAX:
The highest level of density i.e. Maximum Density.
D-MIN:
The lowest level of density i.e. Minimum Density.
DPI:
Abbreviation for Dots Per Inch. A measurement value used to describe the output resolution of a printer.
Driver:
Refers to the software that actually converts image pixel data into data that an inkjet printer can print. The driver is the control point for selecting the printer's output resolution, paper type, and type of color management system being employed.
Dynamic Range:
The difference between the smallest and the largest amount of gray that a system can represent. Also the difference between the lightest highlight and the D-Max in the system.
FireWire:
A type of cabling technology for transferring data to and from digital devices at high speed.
Gamut:
The range of colors that a color system can display or print. The spectrum of colors seen by the human eye is wider than the gamut available in any imaging device.
Among the color spaces used in Photoshop, L*a*b has the largest gamut, encompassing all colors in the RGB and CMYK gamuts. Typically, RGB gamuts contain the subset of these colors that can be viewed on a computer or television monitor (which emits red, green, and blue light).
CMYK gamuts are smaller, consisting only of colors that can be printed using process-color inks.
Histogram:
A bar graph analysis tool that can be used to identify contrast and dynamic range of an image.
Hue:
A component of color, or the wavelength of light of pure color. Hue is the color reflected from or transmitted through an object. It is measured as a location on the standard color wheel, expressed as a degree between 0° and 360°. In common use, hue is identified by the name of the color.
ICC Profile:
A color management workflow based on conventions developed by the International Color Consortium.
JPEG:
Acronym for Joint Photographic Experts Group, the name of the committee that designed the image compression algorithm and file format that is widely supported and recommended for continuous-tone images, such as photographs. Files can be compressed up to 10% of the original file size and offers the end-user different levels of quality. A higher level of compression results in lower image quality, and a lower level of compression results in better image quality.
Lab (Color Mode):
The L*a*b color model is based on the model proposed by the Commission Internationale d'Eclairage (CIE) in 1931 as an international standard for color measurement. In 1976, this model was refined and named CIE L*a*b and is designed to be device independent, creating consistent color regardless of the device (such as a monitor, printer, computer, or scanner).
L*a*b color consists of a luminance or lightness component (L) and two chromatic components: the ?a? component (from green to red) and the ?b? component (from blue to yellow).
In Photoshop, Lab mode (the asterisks are dropped from the name) has a lightness component (L) that can range from 0 to 100. In the color picker, the ?a? component (green-red axis) and the ?b? component (blue-yellow axis) can range from +128 to -128. In the Color palette, the ?a? component and the ?b? component can range from +120 to -120.
Among the color models used in Photoshop, Lab has the largest gamut, encompassing all colors in the RGB and CMYK gamuts.
Layer Mask:
An alpha channel that allows or blocks color effects to alter and manipulate color. A layer mask is a grayscale image, so what is painted in black will be hidden, what is painted in white will show, and what is painted in gray shades will show in various levels of transparency.
Lightfastness:
The degree to which a dye or pigment resists fading due to exposure to electromagnetic radiations i.e. visible light, ultraviolet light etc.
Luminosity:
Refers to the brightness within an image; the relative quantity (brightness) of light; the quality of being luminous; emitting or reflecting light.
When selecting a blending mode In Adobe Photoshop, Luminosity mode creates a resulting color with the hue and saturation of the base color and the luminance of the blend color. This mode creates an inverse effect from that of the Color mode.
Megabyte:
(MB)
A measurement of data storage equal to 1024 kilobytes (KB).
Noise:
Undesirable signals or other artifacts that reduce and diminish the overall quality of a digital image.
Opacity:
The degree to which something reduces the passage of light.
Opacity, in Adobe Photoshop, specifies the maximum amount of paint coverage applied by the brush, paintbrush, pencil, clone stamp, pattern stamp, history brush, art history brush, gradient, and paint bucket tools. For transparent paint or a weak effect, specify a low percentage value; for more opaque paint or a strong effect, specify a high value.
A layer's opacity determines to what degree it obscures or reveals the layer beneath it. A layer with 1% opacity appears nearly transparent, while one with 100% opacity appears completely opaque.
Out of Gamut:
See Gamut.
Output:
A print.
Perceptual:
One of the four ICC rendering intents. Perceptual aims to preserve the visual relationship between colors in a way that is perceived as natural to the human eye, although the color values themselves may change. Although the perceptual rendering intent has traditionally been the most common choice for photographic imagery, Relative Colorimetric - with the Use Black Point Compensation option selected in the Color Settings dialog box - can be a better choice for preserving color relationships without sacrificing color accuracy.
Pixel:
Derived from the word "Picture elements" - the smallest visual unit in a raster file, or a single cell of information. Image files are comprised of thousands or millions of pixels; they are the building blocks of a digital photograph.
PPI:
Abbreviation for Pixels Per Inch. A measurement value used to describe either the resolution of a display screen, image size on a monitor or scanner. See also: Resolution.
RAW:
The RAW image format is data directly from a camera's CCD or CMOS sensor, with no in-camera processing performed.
Red-eye:
The red glow in a subject's eyes. The appearance is caused by light from a flash reflecting off the blood vessels in the retina of the eye.
Relative Colorimetric:
Rendering intent identical to Absolute Colorimetric except for the following difference: Relative Colorimetric compares the white point of the source color space to that of the destination color space and shifts all colors accordingly. Although the perceptual rendering intent has traditionally been the most common choice for photographic imagery, Relative Colorimetric - with the Use Black Point Compensation option selected in the Color Settings dialog box - can be a better choice for preserving color relationships without sacrificing color accuracy. Relative Colorimetric is the default rendering intent used by all predefined configurations in the Adobe Photoshop Settings menu of the Color Settings dialog box. See also: Perceptual
Resolution:
Images on a computer monitor are made by tiny dots of light (pixels). These dots fool the eye into thinking there is an image on the screen. Resolution refers to the number of the dots in terms of pixels per inch (ppi). The higher the number, the more detail an image can have.
Image resolution refers to the number of pixels per unit of measure in the digital image, commonly expressed in pixels per inch (ppi.) This should not be confused with dots per inch (dpi), which is a measurement of output resolution on a printer.
The quality of any digital image, whether printed or displayed on a screen, depends in part on its resolution. In general the higher the resolution the greater the detail.
RGB:
Abbreviation for Red Green Blue, the primary colors from which all other colors are derived. An additive, light-based, color space that creates color by adding varying amounts of Red Green and Blue.
Saturation:
Sometimes called chroma, or intensity, is the strength or purity of the color and the degree to which a color is undiluted by white light. If a color is 100 percent saturated, it contains no white light. If a color has no saturation, it is a shade of gray.
Saturation represents the amount of gray in proportion to the hue, measured as a percentage from 0% (gray) to 100% (fully saturated). On the standard color wheel, saturation increases from the center to the edge. In digital imaging, saturation relates to how rich the colors are in an image.
Sharpening:
In digital imaging Sharpening is done by increasing or decreasing the contrast between pixels along the pixel's edges. Unsharp masking, or USM, is a traditional film compositing technique used to sharpen edges in an image. The Unsharp Mask filter in Adobe Photoshop corrects blurring introduced during capture, scanning or resampling.
Soft Proof/Proof:
In a traditional publishing workflow, one would print a hard proof of a document to preview how the document's colors will look when reproduced on a specific output device. In a color-managed workflow, one can use the precision of color profiles to soft-proof a document directly on the monitor - to display an on-screen preview of the document's colors as reproduced on a specified output device. In addition, a printer can be used to produce a hard-proof version.
Substrate:
The printable surface of any media such as inkjet paper.
Ultrachrome Ink:
Pigment inks ground via an ultrasonic process to insure uniform particle size that are then coated with a polymer to insure even ink lay down. Inks made with this process have yield prints with increased color gamut and contrast.
