Geoscience Reference
In-Depth Information
8 Image Processing
Pollen grains, mostly Asteraceae and less
abundant Caesalpiniaceae and Lamiaceae
pollen, in a microscope image of Argentine
honey. The methods of image processing have
been used to enhance the quality of the image.
Image analysis is then used to determine the
number of pollen grains in such an image.
8.1 Introduction
Computer graphics are stored and processed as either vector or raster data.
Most of the data types that were encountered in the previous chapter were
vector data, i.e., points, lines and polygons. Drainage networks, the outlines
of geologic units, sampling locations, and topographic contours are all
examples of vector data. In Chapter 7, coastlines are stored in a vector format
while bathymetric and topographic data are saved in a raster format. Vector
and raster data are ot en combined in a single data set, for instance to display
the course of a river on a satellite image. Raster data are ot en converted to
vector data by digitizing points, lines or polygons. Conversely, vector data
are sometimes transformed to raster data.
Images are generally represented as raster data, i.e., as a 2D array of color
intensities. Images are everywhere in geosciences. Field geologists use aerial
photos and satellite images to identify lithologic units, tectonic structures,
landslides and other features within a study area. Geomorphologists use
such images to analyze drainage networks, river catchments, and vegetation
or soil types. h e analysis of images from thin sections, the automated
identii cation of objects, and the measurement of varve thicknesses all make
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