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Message-ID: <074701c092cd$85206e60$0101a8c0@zebu>
From: "Alex" <alexcher@pop.mail.rcn.net>
To: <tiff@olympiakos.com>
References: <12E4115024E9D411949100508BB0C9DA34F0BC@NTS_WAL_MAIL>
Subject: Re: turning TIFF Images
Date: Fri, 9 Feb 2001 14:21:34 -0500
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Hi Juergen,

As a PostScript expert here I can recommend to convert the
TIFF to PostScript and use rotate operator. This is a fine
approach if you want to print your map.

if you want to get another TIFF or display the result on the
screen you need to write a simple program that iterates
over the rotated image and picks pixels from the source image.
This is simple approach but it can be slow.

At small angle rotation can be done as 2 shifts in X and Y
direction proportional to the distance to the row or column.
This is a simple operation that can easily use
processor-specific tricks to shuffle bits around.

Regards,
Alex

----- Original Message -----
From: Braukmann, Juergen <Juergen.Braukmann@lua.nrw.de>
To: <tiff@olympiakos.com>
Sent: Friday, 09 February, 2001 09:13
Subject: turning TIFF Images


> Hello everybody,
>
> is there any tool that enables me to turn a tiff Image for a few degrees (or
> fractions) and save the result in another TIFF?
>
> I need to turn maps for out GIS System... (This is the price I've to pay to
> the fact that the earth isn't a flat disc) ;-(
>
> Juergen
>


