[Image-SIG] Image perspective with PIL

[PyProg PyProg]

2010/5/3 Fredrik Lundh <fredrik at pythonware.com>:

> I've added the documentation from the original patch to this page:
>
>  http://effbot.org/tag/pil.Image.Image.transform
>
> The next text is attached below.
>
> </F>
>
> im.transform(size, PERSPECTIVE, data)
>
> im.transform(size, PERSPECTIVE, data, filter)
>
> Applies a perspective transform to the image, and places the result
> in a new image with the given size.
>
> 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.
>
> This function can be used to change the 2D perspective of the
> original image.

Hello

The problem is that I do not understand what that means: "which
Contains the coefficients for a perspective transform ... "... and in
particular what exactly match a, b, c, d, e, f, g and h.

If you are patient (excuse me), can you explain with precision (and a
didactic, for someone who has trouble like me) what these data (and
possibly with an example of processing with good values for a, b, c,
d, e, f , g and h).

Thank you in advance.

a+

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