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updated : wed 21 aug 2002 4:05pm bst
go : home | tutorials | making a densitometer


A densitometer measures the overall brightness level of an image at a certain point; this is useful, for example, in astronomical image processing and constructing flat-field masks to counteract vignetting. Photodesk's Info window doesn't have a densitometer setting, but you can simulate this by copying your image to an alpha channel and nominating the channel as the mask; the M value in the Info window will then show the amount of black in the image. The easiest way to do this is as follows:

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