"Thorsten Froehlich" <tho### [at] trfde> wrote in message 
news:4149f442@news.povray.org...
> In article <4145d55e$1@news.povray.org> , "Jeremy M. Praay"
> <sla### [at] hotmailcom> wrote:
>
>> Someone can correct me (again) if I'm wrong, but the "big" render size 
>> would
>> have to be at least 5334x4000 in order to get an 800x800 detail view that
>> was <= 1/25 of the original picture.
>
> You are wrong.  The detail image size has to be at least 800 by 800.  This
> says nothing about the part in the main image. The rules only require that
> the area in the main image the detail image shows is not more than 1/25 of
> the total main image area.  You could pick a 1 by 1 pixel area in the main
> image and render that with a resolution of 800 by 800 easily.
>


I'm not sure that I follow.  Either that or you didn't follow me.  I think 
you're saying that my first estimate of 4800x3600 was closer (obviously 
assuming 4:3 aspect ratio for the original image), though a little on the 
high side.

To avoid any further misunderstandings, my contention is that by using 
+sr/+sc/+er/+ec, we would have to take a 800x800 detail section of an image 
that was not less than 4619x3465 (still assuming 4:3 aspect ratio), if it 
was rendered in full, in order to get a detail section that was less than or 
equal to 1/25 of the entire image.  I suppose those dimensions may be 
negociable by a pixel for each dimension, depending on how/where things get 
rounded.

-- 
Jeremy
www.beantoad.com