[FFmpeg-devel] [PATCH] adjust y in pad filter

Reimar Döffinger Reimar.Doeffinger
Tue May 11 21:32:50 CEST 2010

On Tue, May 11, 2010 at 11:04:48AM -0700, Baptiste Coudurier wrote:
> On 05/11/2010 10:55 AM, Baptiste Coudurier wrote:
> >On 05/11/2010 10:50 AM, Reimar D?ffinger wrote:
> >>On Tue, May 11, 2010 at 10:33:51AM -0700, Baptiste Coudurier wrote:
> >>>I believe that it is simpler and obvious for everybody that
> >>>0,0 coordinates are bottom left corner and not top left corner.
> >>
> >>Not to me, I've never understood why it should be, does anyone
> >>number line numbers on a page from bottom to top?
> >>Why the should pixels suddenly be counted that way?
> >
> >What about maths ?
> >
> To elaborate, it is about geometry.
> In geometry, 0,0 is bottom left.

No, 0,0 is just the distinguished point, there's no "left", "bottom" or
whatever in geometry, even if it is usually drawn like that.
Either way, I see almost no relation between an (digital) image and geometry,
images are discreet and finite, something you'll almost never encounter in geometry.
They are much closer to both arrays and matrices, and nobody I know of ever has
put the (0, 0) element of these in the lower left.
Even in OpenGL the coordinate system switches between texture upload (when you are
still dealing with discreet pixels) and actually using a texture (where a float
value is used).

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