Art, I really am not trying to pick on you (ok, yes I am); scanners techically measure resolution in terms of samples per inch or spi. Thus, Your correction below is wrong. "That would mean if the scanner claimed a 4000 dpi (really ppi or pixels per inch) resolution...." It is really 4000 spi and not ppi.
> But yes, the file size grows 4x if > the scanner resolution is doubles, assuming the same bit depth > capture is used. I think that he was asking more about if this causes an increase in the image size and not the file size; but I could be wrong. [EMAIL PROTECTED] wrote: > Most color film scanners use a CCD chip which has a series of three > lines across it each with a color filter over it, Red, Green or Blue, > which each are made up of a series of sensors. (Nikon uses a slightly > different method, but I don't want to confuse things). > > That line contains a specific number of sensors across it. For > simplicity, let's assume a film frame is one inch across by 1.5" wide. > That would mean if the scanner claimed a 4000 dpi (really ppi or > pixels per inch) resolution, the image dimensions when a file was > created would be 6000 pixels by 4000 pixels. > > The film or sensor stage is moved one pixel width per scan cycle until > 6000 cycles (for a 1.5" "long" film frame) are achieved. > > The image is actually projected onto the CCD sensor, so the sensor's > length might be larger or smaller than the film dimensions. > > If the exact same sensor was used in a medium format film scanner, > which had, say a 2" wide film frame, that would be scanned at 2000 > ppi, since the same number of sensors would be reading information > projected on it from a film frame twice as wide. > > I have simplified this process. But yes, the file size grows 4x if > the scanner resolution is doubles, assuming the same bit depth > capture is used. > > Art > > [EMAIL PROTECTED] wrote: > >> I'm a bit perplexed at what the dpi means on a film scanner. Trying >> to compare apples to apples, will a 4000 dpi Brand X film scanner in >> theory produce a better quality image outputted than a 2000 dpi >> Brand X scanner, given that the output resolution is the same, say >> 1600 x 2400 pixels? >> >> Or does it simply mean the 4000 dpi scanner will output a much larger >> image than the 2000 dpi model? >> >> Thanks for clearing this up, >> Bill >> >> > > -------------------------------------------------------------------------- -------------- > Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe > filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) > in the message title or body > > > --- > Incoming mail is certified Virus Free. > Checked by AVG anti-virus system (http://www.grisoft.com). > Version: 6.0.617 / Virus Database: 396 - Release Date: 3/9/04 --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.617 / Virus Database: 396 - Release Date: 3/9/04 ---------------------------------------------------------------------------------------- Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body