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Table Of Contents
13.2 Image Formats: Bitmapped, Vector, and Metafile Formats
What is the difference between bitmapped, vector, and metafile image formats?
Bitmapped (or raster) and vector are two broad categories of file formats for images. Metafile image formats
can contain images in both bitmapped and vector formats. PlanetPress Design supports all three categories of
formats.
13.2.1 Bitmapped File Format
A bitmapped file format stores an image as a set of pixels. Common bitmapped formats are BMP, TIFF, PNG
and JPEG. Images such as photographs typically use a bitmapped format.
The disadvantages of bitmapped images are loss of image quality when scaling, and large file sizes for images
with large pixel dimensions and color depths.
13.2.2 Vector File Format
A vector file format encodes an image as a set of commands or mathematical equations. Encapsulated
PostScript (EPS) is a common vector format. Images such as illustrations typically use a vector format.
In a vector format, the commands precisely describe how to draw the image. To gain some insight into how
the commands in a vector format describe an image, consider how you might do so in a natural language. For
example, consider a natural language description of an image that consists of a square:
The advantage of images in vector format is that they scale without loss of color, detail, or sharpness.
Depending on the complexity of the image they describe, they may also have a smaller file size than their
bitmapped counterpart. The disadvantage is that they require the computer or printer to interpret the
commands and render the image.
13.2.3 Metafile Formats
A metafile image format can include both bitmapped and vector images. PlanetPress Design supports images
in both Encapsulated PostScript (EPS) and Portable Document Format (PDF) metafile formats.
As for vector images, a metafile image file specifies a size for the image. In this case, if the metafile image
contains bitmapped images, scaling it may affect the image quality of those bitmapped images.
Related topics:
Static and Dynamic Images (Page 168)
Resources (Page 159)
Supported Image Formats (Page 169)
Resolution (Page 172)
Color Depth (Page 192)
Pixel Dimensions (Page 175)
Image Quality (Page 176)
Scanline Orientation (Page 352)
Image Size on the Document Page (Page 179)
PlanetPress Talk Expressions for Dynamic Images that Reference Image Resources (Page 180)
PlanetPress Talk Expressions for Dynamic Images that Reference External Images (Page 181)
Image Name and Pathname Resolution in Dynamic Images (Page 187)
Caches (Page 188)
Guidelines for Optimizing Images (Page 189)
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