The following figure shows an application program that allows users to search for images in a database using a visual example as search criteria, that is, an image that demonstrates a predominant color or texture pattern. With such an application, users can supply an image as input to the search. The application then matches the color or texture of the source image against those of the stored images, and returns the images whose color or texture most closely match the input.
Figure 19. Query by image content
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This capability to query images by their visual features is called Query by Image Content (QBIC) 5. This chapter describes how to use APIs and UDFs that are provided with the Image Extender to build applications like the one just described. It also describes how to use commands and APIs that are provided with the Image Extender to perform QBIC administrative tasks.