corners

spizzle.corners(pixmap, pixfrac=1.0)

Output coordinates of the corners of every shrunken input pixel.

The corners are at (x - h, y + h), (x + h, y + h), (x + h, y - h) and (x - h, y - h) in the input frame, in that order, with h = pixfrac / 2. Interior pixels use drizzle’s nine-point interpolation and pixels within one pixel of the left and bottom edges, or two pixels of the right and top edges, use bilinear interpolation of each corner, extrapolating at the image edge, as drizzle does.

Parameters:

pixmapndarray, shape (ny, nx, 2)

Output x and y coordinates of each input pixel center. NaN marks pixels without a mapping.

pixfracfloat

Linear size of the shrunken pixel as a fraction of the input pixel.

Returns:

ndarray, shape (ny, nx, 4, 2)

Output x and y of the four corners of each input pixel; NaN where an interpolation used a NaN in the pixel map.