Libraries and Packages: The VOS Interface
The pixel list package is a general package for flagging individual pixels or regions of an image, to mark some subset of the pixels in an image. This may be done to flag bad pixels, or to identify those regions of an image to be processed by some applications program. When the pixel list package is used to flag the bad pixels in an image we call this a bad pixel mask, or BPM. When used to identify the regions of an image to be processed (or ignored), the list is called a region mask. The document Pixel List Package Design [Tody88] fully describes the details of the pixel list package. Here we only summarize and present a brief example. Example 2.30 opens a data image and the associated mask image, and sums the pixels within the area indicated by the mask.
A more complex application might use the spatial information provided by v and npix, or the flag values provided by mval (for an integer mask). For example, a surface fitting routine would accumulate each line segment into a least squares matrix, using the coordinate information provided as well as the pixel values.
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