Originally Posted by jford
Reading this got me wondering - is the file spooled to the printer "saved" in any fashion? I understand and completely agree that the originally opened file on the hard disk would be unaffected. But there is a "copy" made in RAM when a file is printed (or copied or otherwise internally manipulated). It seems to me that this spooled copy MAY be of different quality than either the original HD file OR the virtual copy internal to PS (or other image processing software).
Not sure if this makes sense or not, but I was just curious.
Yes the printer file is different than the photo file you started with or its internal representation in the Memory of the program you're printing it out of. The printer drivers change the file appropriately for the printer's use and so the quality of the print drivers will effect the ultimate printed result. That is why for years there have been drivers available for printers that are sometimes so for an extra cost and give better results than the driver that comes with a printer. Is the quality different? It can be.
Its sort of like translating text from one language to another. It depends on the translator as to how certain words will be rendered.
For example, take the text in Greek:
polus protos eschatos eschatos protos
which one translator rendered:
But many that are first shall be last; and the last shall be first.
and another rendered:
But many who are first now will be last then;
and some who are last now will be first then.
Quite a difference, but both are acceptable translations. But each gives a different picture to the reader.
Another factor is whether you let the program control certain aspect of the printing or whether you pass it off totally to the printer driver. For example Photoshop gives you the ability to do that.
There is no lossy compression taking place however, so all of the available data "could" be used by the driver or the program or a combination of both.