Paul Weyn wrote:
Hi Andy,
Not sure I understand the process exactly either but when I have a 35mm
negative scanned to be printed at a maximum 20x24 size, the file size
created by my lab is about 80meg. In my mind, that's huge; however, the
results are extremely good - no pixilation at all. However, I do not
understand the math because if the printer can only go as high as 300 DPI
then why is so large a file needed...are the rest of the pixels just
discarded in the process, and if so then why wouldn't a smaller file work
just as well?
300 pixels per linear inch means 90,000 pixels per square inch. A 20x24
print is 480 square inches, so the entire print is 43,200,000 pixels.
In 24-bit color each pixel is 3 bytes. So an uncompressed file for a
20x24 print at 300 pixels per inch would be about 129,600,000 bytes.
In other words, you 80 meg file isn't even enough for 300 pixels per inch.
--
David Dyer-Bennet, dd-b@xxxxxxxx; http://dd-b.net/dd-b
Pics: http://dd-b.net/dd-b/SnapshotAlbum, http://dd-b.net/photography/gallery
Dragaera: http://dragaera.info
