Colin <kla### [at] essexacuk> wrote:
> The output image is rendered to 384x288 (which is the same aspect ratio
> as the default povray camera ratio). And here is the texture mapping
> code, which simulate a marker that has printed on an A4 size paper:

I have an idea about what can cause this problem. The aspect of your image
is exactly 4/3 - counting in pixels. It is also displayed on screen with
aspect 4/3. This makes the distortion because typical PAL devices use
pixels which are not square. Your image should have 352 pixels in height
what is 1/2 of PAL resolution and what makes the whole visible area on 4/3
monitor. The rest of the pixels are margins which are usually hidden.

PAL resolution = 704 x 576 and is displayed on 4/3 screen
Half of PAL =    352 x 288 also displayed in 4/3
Pixel aspect = (704/4) / (576/3) = 0,9166 (width/height)

Your capture device gives you the whole image, without clipping the margins.
So you have to clip them by yourself to size 352 and then stretch the image
to aspect 4/3.

The other and maybe simplier solution is to add:
"right (4/3) / 0,9166"
to your camera definition.
However it has an disadvantage because both images remain distorted and if
your software makes use of sizes measured on the image it may cause an
error.

Greetings!
Przemek

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