1999.12.05 23:42 "Re: X & Y Resolution", by Niles Ritter
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.