- daylight film
- Most colour film is designed for use under natural light only. As light changes colour from bluish in the morning through white at midday to reddish in the evening our eyes compensate without us knowing. Daylight film however records the different qualities of light and may give more exaggerated-colour results than we remember.
- depth of field
- Depth of field is the amount of sharp detail you set between the foreground and background parts of your picture. You need to pick out the most important bit to focus on then decide how much sharp detail you want to show around it. Smaller f numbers give less depth of field and bigger f numbers give more depth of field.
- Desktop
- A Desktop refers to computer and imaging systems linked to personal computers (PC's) such as Apple Macintosh or Intel Pentium computers as opposed to larger workstation type of computers such SUN or Silicon Graphics. Desktop systems use operating systems such as Macintosh OS or Windows 95. Workstation systems typically use UNIX or Windows NT.
- Digital
- The process of representing and processing information that has been converted to binary numeric data. A digital image is made up of rows and columns of individual picture elements (pixels). In a full color RGB image each pixel is encoded as three 8 bit binary numbers which represent the brightness level each of the three colors (RGB). Because the entire image is recorded as a vast array of numbers it is possible for a computer to perform calculations on those numbers in order to manipulate the images.
- Displacement
- Camera displacements are a feature of Large Format studio cameras that allow the relationship between the film plane and the lens plane to be altered in order to alter and control the perspective of the image. By using displacements it is possible for example to look up at a building and keep the vertical sides of the building parallel without having the keystone effect normally experienced with a camera.Digital cameras do not work well with significant displacements. The control of perspective is often best left to be accomplished in Photoshop
- Dithering
- When a monitor cannot display intermediate colors or tones it attempts to achieve the required color by intermixing the two closest colors in a scattering (dithering) of pixels. This occursmost often when you attempt to display a full color image on a monitor with a 256 or a 64000 color video display board. In an illustration dithering can make typography almost impossible to read.
- Dot
- Strictly speaking a dot is the smallest spot an imagesetter or printer can output and is usually expressed in dots per inch (dpi). However the term dot is often used interchangeably with Pixels (ppi) or Halftone Cells (lpi or L/S). An imagesetter dot is of a specific and unvarying size. A 300dpi laser printer can only make dots that are 1/300 of an inch in diameter. To make a bigger spot it uses several dots. On the other hand a halftone dot varies in size in order to simulate continuous tone. (see: Halftone)
- dpi
- Dots per Inch
- DX coding
- In case you forget to set your film speed DX coding sets it for you automatically. A checkerboard pattern found on the film cassette describes the film speed in a kind of code. Sensors in modern cameras (made in the last 10 years) read this like scanners at a supermarket checkout read barcodes.
- Dye Sublimation
- A type of continuous tone printing process that produces a vibrant 300ppi color print. The pixels are printed by a thermal print head that sublimates (vaporizes) the dye from a colored saran wrap like ribbon onto the dye-sublimation paper. The hotter the element on the thermal printing head the darker the spot of color.
- Dynamic Range
- The dynamic range or Optical Density of a scanner is a measure of the range of densities and the deepest shadow density that the scanner can see into and record information. If the dynamic range of the transparency exceeds that of the scanner then the scanner will perceive everything beyond its range as black. A Drum Scanner with a Dynamic Range of 3.8D and a bit depth of 48 will produce a much higher quality richer more detailed scan than a Flatbed Scan with a Dynamic Range of 2.5D and a bit depth of 24 at the same scan resolution.
