Message-ID: 384AF85D.B71FA62E@earthlink.net
To: Kambiz Asrar Haghighi <kambiz@interchange.ubc.ca>
Subject: Re: X & Y Resolution
From: Niles Ritter <ritter@earthlink.net>
Date: Sun, 05 Dec 1999 23:42:21 +0000
CC: TIFF Mailing List <tiff@olympiakos.com>
References: <Pine.GSO.4.20.9912051208170.14305-100000@inch.interchange.ubc.ca>
Sender: owner-tiff@olympiakos.com


Kambiz Asrar Haghighi wrote:

> Hi,
>
> I've tried to understand what Xresolution and Yresolution are from the
> tiff specification, but I still don't understand how I would go about
> deciding the values for these fields based on the number of pixels I have
> in my image. I know the value of the width and height, but is there any
> correlation between these and the above values?
>

The X and Y Resolution refer to the relationship between image pixels
and linear units in external devices, such as scanners and printers.  For
example, in principle if a document is scanned at 300 dots per pixel and
this is noted in the TIFF file , and the image printing software honors
this value, the final output print will match the original document.

Note however the TIFF spec says that it is not mandatory that the
image be displayed at the size specified, but is up to the application to
use this information as it pleases.  For digital photographs this value
is somewhat meaningless since actual size depends upon depth of
field which usually varies in the image.

 --Niles.


