7.6

Term: Means:
Scan res-
olution
The resolution at which you scan an image on a scanner. It refers to the number of samples per inch (spi), where
each sample represents a single pixel in the resulting bitmapped image.
Display
resolution
The resolution of the monitor screen. For example 96 DPI means the screen displays 96 pixels per inch. Thus an
image with pixel dimensions of 96 x 96 would measure 1 inch x 1 inch on this monitor screen.
Printer
resolution
The number of spots of ink the printer can produce per inch, commonly measured as dots per inch (DPI). The use of
DPI as a measure can be confusing as it may be interpreted as meaning one dot of ink maps to one image pixel. In
fact the number of spots of ink the printer uses to represent a single pixel can vary with the halftone screen used for
a print job (the lines per inch (LPI)), the color depth of the image, and the algorithm the printer uses to represent
individual colors.
Color Depth
Color depth refers to the number of colors each individual pixel in a bitmapped image can display. Color depth is expressed in
bits per pixel where each individual bit can take on one of two values (0 or 1).
Pixel Dimension
Pixel dimensions refer to the number of pixels in the width and height of a bitmapped image. Thus an image with pixel dimen-
sions of 200 x 300 has a width of 200 pixels and a height of 300 pixels. Pixel dimensions do not define a fixed size for the bit-
mapped image. Rather the resolution determines the final physical dimensions of the image. See "Resolution" (page n) for help
understanding resolution in PlanetPress Design.
You can adjust the pixel dimensions of a bitmapped image to adjust the size it occupies at a given resolution. This is called
resampling the image, and it is particularly useful for large image files that contain more pixels than are necessary to produce
the highest quality output.
Image Quality:Line Art
In line art quality, the edges of different elements of the image are clearly visible and sensitive to any increase or decrease in
pixel dimensions that occurs through resampling. As an example of line art, think of a corporate logo. A logo typically uses flat
areas of color with each area clearly distinguished from the other. PlanetPress Design uses a lossless compression for line art
quality images. A lossless compression preserves all image information.
Image Quality:Photo
In photo quality, edges of elements are not as clearly delineated and are consequently less sensitive to any increase or
decrease in pixel dimensions that occurs through resampling. As an example of photo quality, think of a photograph of a nat-
ural object or landscape; there are many subtle tones and gradations, even along the edges between elements. PlanetPress
Design uses a lossy compression (JPEG compression) for photo quality images. A lossy compression does not preserve all
image information. In the case of photo quality, you set a compression level that determines how much image information is
lost. An appropriate compression level results in no visible deterioration of quality in the document output.
Scanline Orientation
Scanline orientation refers to the way in which the laser in a laser printer writes the page image onto the printer drum. In Plan-
etPress Design you can use this information to minimize the amount of runtime processing bitmapped image resources
require, and thereby contribute to minimizing the overall execution time of a document.
You determine the scanline orientation for an image resource from three pieces of information: the paper orientation selected
in the document for the page containing the image resource, how the paper enters the printer, and the scanline orientation of
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