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Re: Backend and non-backend (was Re: Stencil bounding box)


From: David Feuer
Subject: Re: Backend and non-backend (was Re: Stencil bounding box)
Date: Tue, 2 May 2006 14:51:04 -0400

On 5/2/06, Han-Wen Nienhuys <address@hidden> wrote:

How will you deal with two images that have different sizes? What will
happen if the entire 2nd image is shifted vertically and horizontally by
two pixels. This typically gives a huge difference (all staff lines and
stems will no longer overlap), but there really is (almost) no change in
formatting.

Yeah, true.  It'd work for testing changes that aren't supposed to
change positions more than a tiny fraction, but otherwise not.

One possibility:  Take all image elements (on a high level I guess
this would be grobs, on a low level it'd be stencil pieces).  Separate
them by type (stems here, noteheads there; rectangles here, glyphs
there), and within each type sort them by left edge of bounding box,
bottom edge of bounding box, width, and height.  Count to see if there
are the same number of elements of each type, then pair up
corresponding elements and compute the correlation coefficients or
similar statistics for the coordinates of pairs.

David




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