>If you scan at 1200dpi, the scanner usually either samples all the 4800 >possible data points per inch and throws three out of every four away, or >only samples every fourth possible point. So you are only getting one >quarter of the possible data from the film. So why scan at large format if >you are throwing three quarters of the film data away?
Bob, I beliee you are correct; but I do not understand your question. What do you mean by "scan at large format" in this case? I must have missed something in the discussion. The first method,which you note, involves the actual sampling of original data using sampling algorithms and does result in a loss of ortiginal data; but the second method, which you speak of with respect to Vuescan and is available in almost all other scnning applications, involves resampling of the original sample data using formulas for combining and recombining data on the basis of all existing data and the formulas. Both methods, however, would involve the scanner reading during the scan all 4800 points; so both would involve a "scan at large format" - using your terms - or whatever optical format is used by the scanner. After the scan, everything else by way of sampling or resampling is either digital conversion via hardware or software generated. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Bob Frost Sent: Thursday, December 09, 2004 4:10 AM To: [EMAIL PROTECTED] Subject: [filmscanners] scanning at less than optical res Is this correct? "As I understand things, a scanner with an optical resolution of 4800dpi can take a sample reading every 1/4800 of an inch. If you scan at the optical resolution, that is what is does and you get 4800 readings per inch along that axis (usually a different resolution on the other axis). If you scan at 1200dpi, the scanner usually either samples all the 4800 possible data points per inch and throws three out of every four away, or only samples every fourth possible point. So you are only getting one quarter of the possible data from the film. So why scan at large format if you are throwing three quarters of the film data away? With Vuescan software, you can set it to scan all 4800 data points per inch, but then to take the average of every four data points and reduce them to one, so that the file you get out is the equivalent of a 1200dpi scan, but all the data points have contributed to the final result." Bob Frost. ---------------------------------------------------------------------------- ------------ Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body -- No virus found in this incoming message. Checked by AVG Anti-Virus. Version: 7.0.289 / Virus Database: 265.4.8 - Release Date: 12/8/2004 -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.289 / Virus Database: 265.4.8 - Release Date: 12/8/2004 ---------------------------------------------------------------------------------------- Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
