I found the matrix data in Jeff Breidenbach's original posting here on 2005-02-16:- "Data is a 8-tuple (a, b, c, d, e, f, g, h) which contains the coefficients for a perspective transform. For each pixel (x, y) in the output image, the new value is taken from a position (a x + b y + c)/(g x + h y + 1), (d x + e y + f)/(g x + h y + 1) in the input image, rounded to nearest pixel." It works fine in 1.1.5. The question remains: what transform does QUAD apply? I would have expected it to use a perspective transform like the one in the Java Advanced Imaging method getQuadToQuad, which creates a PerspectiveTransform that maps an arbitrary quadrilateral onto another arbitrary quadrilateral.
Fredrik Lundh wrote: > > Christopher Jones wrote: > >> I have just discovered that the QUAD transform is not perspective: it >> does >> not preserve straight lines in the original image. Any way of doing a >> perspective transformation? > > in 1.1.5 and later, transform can take a PERSPECTIVE transform matrix, > but I cannot seem to find any documentation on how the matrix data > should look. > > checking the mailing list archives or the source is your best bet. > > </F> > > _______________________________________________ > Image-SIG maillist - [email protected] > http://mail.python.org/mailman/listinfo/image-sig > > -- View this message in context: http://www.nabble.com/PIL-QUAD-transform-tf2517519.html#a7040656 Sent from the Python - image-sig mailing list archive at Nabble.com. _______________________________________________ Image-SIG maillist - [email protected] http://mail.python.org/mailman/listinfo/image-sig
