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Just wondering if anyone's used or created image comparison capabilities for use from SQL Anywhere blobs. For example, if I have a long binary cell with a JPG, PNG or other image in it, is there a function like HASH that could produce a value that "describes" the image. One tricky piece is that there are several variants of "describe" - I'm certainly interested in standard metadata (image attributes - size, compression, etc.; content - photographer, location, data/time, etc.) but I'm also interested in certain "content" or "embedded" metadata, as in "this is a picture of horse", or "the predominant/average colour of this picture is brown with a white splotch in the bottom right" (as in Google Image, and other image search facilities). For reference, there's a good description of what another database engine provides, with lots of background about image metadata at http://docs.oracle.com/cd/B28359_01/appdev.111/b28415/ch_metadata.htm - currently I have no interest in DICOM metadata (medical images), but others might. |
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SQL Anywhere has a hash function - surprisingly it is called hash ! See the documentation for more information. Regarding meta data, your will most likely need to have separate columns (or a 'meta data' table) to contain this information. You could consider writing an external store procedure (or use an external environment) that would take the image and automatically extract some the meta data for you. HTH |
