Glossary

Adobe Camera Raw (ACR): Used to convert RAW files into files that Photoshop can open.

Ambient light: The available, or existing, light that naturally surrounds a scene.

Aperture: The size of the opening in the iris of a lens. Lens apertures are designated by f-numbers. The smaller the f-number, the bigger the opening, and the less depth-of-field.

Blending mode: Determines how two layers in Photoshop will combine.

Bracketing: Shooting many exposures at a range of settings. It often works better to bracket shutter speed rather than aperture.

Brush Tool: Used to paint on a layer or layer mask in Photoshop.

Channel: In Photoshop, a channel is a grayscale representation of color (or black) information. In RGB color there are three channels: Red, Green, and Blue.

Chiaroscuro: Moody lighting that shows contrasts between shadows and brightness.

CMYK: Cyan, Magenta, Yellow, and Black. The four-color color model used for most offset printing.

Color space: A color space, sometimes called a color model, is the mechanism used to display the colors we see in the world, in print, or on a monitor. CMYK, LAB, and RGB are examples of color spaces.

Composite: Multiple images that are combined to create a new composition.

Depth-of-field: The field in front of and behind a subject that is in focus.

DICOM file: Digial Imaging and Communication in Medicine file format.

Diffraction: Bending of light rays; unwanted diffraction can cause loss of optical sharpness, particularly at small apertures.

DSLR: Digital single lens reflex camera.

Duotone: A historic printing process that created rich monochromatic imagery using two colors of ink.

Dynamic range: The difference between the lightest tonal values and the darkest tonal values in a photo.

Effective aperture: The aperture recorded by EXIF data as opposed to the aperture set on the camera. In close focus, the effective aperture is often a smaller opening than the set aperture.

EV (Exposure Value): Denotes any combination of aperture, shutter speed, and ISO that yields the same exposure. –1 EV means halving the exposure, and +1 EV means doubling the exposure.

Exposure: The amount of light hitting the camera sensor. Also the camera settings used to capture this incoming light.

Exposure histogram: A bar graph displayed on a camera or computer that shows the distribution of lights and darks in a photo.

Extension tube: A hollow ring that fits between a lens and the DSLR, used to achieve closer focusing.

f-number, f-stop: The size of the aperture, written f/n, where n is the f-number. The smaller the f-number, the larger the opening in the lens; the larger the f-number, the smaller the opening in the lens.

Focal length: Roughly, the distance from the end of the lens to the sensor. The sensor’s position is also called the focal plane. The location of the focal plane (the distance from which focal length is measured) is indicated on most camera bodies with a special symbol, . The horizontal line in the symbol indicates the position of the focal plane, used for determining the focal length when it is needed precisely.

Framing: In a photographic composition, positioning the image in relationship to its edges.

Gradient: A gradual blend, often used when working with layer masks in Photoshop.

Grain: Texture found in photographic film and prints due to the residue of small grains of metallic silver left over from chemical developing. Grain can be simulated in a digital photo.

Grayscale: Used to render images in a single color from white to black; in Photoshop a grayscale image has only one channel.

Hand-HDR: The process of creating an HDR image from multiple photos at different exposures without using automatic software to combine the photos.

HDR: Extending the dynamic range in an image using techniques including multi-RAW processing, hand-HDR, and automated HDR software.

High key: Brightly lit photos that are predominantly white, often with an intentionally “overexposed” effect.

Hyperfocal distance: The closest distance at which a lens at a given aperture can be focused while keeping objects at infinity in focus.

Image stabilization: Also called vibration reduction, this is a high-tech system in a lens or camera that attempts to compensate for, and reduce, camera motion.

In-camera multiple exposure: Exposures made on a single captured frame in the camera, and blended in the camera.

Infinity (∞): The distance from the camera that is far enough away so that any object at that distance or beyond will be in focus when the lens is set to infinity, regardless of aperture.

Infrared (IR) photography: Captures made using infrared rather than normal, visible light.

iOS: Operating system for the Apple iPhone and iPad.

ISO: Scale used to set a camera’s sensitivity to light.

JPEG: A compressed file format for photos that have been processed from an original RAW image.

LAB color: A color model consisting of three channels. See page 214.

Layer: Photoshop documents are composed of layers stacked on top of each other.

Layer mask: Masks are used to selectively reveal or hide layers in Photoshop.

Low key: Dimly lit photos that are predominantly black, often with an intentionally “underexposed” effect.

Macro lens: A lens that is specially designed for close focusing; often a macro lens focuses close enough to enable a 1:1 magnification ratio, so that the image on the sensor is as large as the image in real life.

Monochrome, monochromatic: A monochrome image is presented as nominally consisting of tones from white to black; however, “black and white” images can be tinted or toned, and usually vary from straight grayscale.

Multi-RAW processing: Combining two or more different versions processed from the same RAW file to extend the dynamic range and create a more pleasing final image.

Open up, open wide: To open up a lens, or to set the lens wide open, means to set the aperture to a large opening, denoted with a small f-number.

Pinhole camera: A camera that uses a literal, very small hole as the lens to capture an image.

Pre-visualization: Understanding, or seeing in one’s “mind’s eye,” before making an exposure how an image will come out after capture and processing.

RAW: A digital RAW file is a complete record of the data captured by the sensor. The details of RAW file formats vary among camera manufacturers.

RGB: Red, Green, and Blue; a three-color color model, used for displaying photos on the web and on computer monitors.

Sensitivity: Set using an ISO number; determines the sensitivity of the sensor to light.

Shutter speed: Shutter speed is not a speed. Rather, it is the interval of time that the shutter is open. This interval controls how objects in motion are rendered.

Solarization: Reverses, or partially reverses, blacks and whites. In film photography, using re-exposure to make partially developed material lighter, simulated in digital photography; also known as the Sebattier effect.

Split toning: Toning with two colors; often one toning color is applied to highlights and the other to shadows.

Stop down: To stop down a lens means to set the aperture to a small opening; denoted with a larger f-number.

Tinting: Adding color to a monochromatic image.

Tonal range: The range of color and light and dark values in an image.

Toning: In the chemical darkroom, toner such as sepia or selenium was added for visual effect; in the digital darkroom, toning simulates the impact of chemical toning.

X-Ray: Radiation shorter in wavelength than visible light.