I thought a line or two might help for those less file type savvy:

Line art in computers (i.e., plans) comes in one of two flavors - raster or vector. Raster file types are typically used for complex images that can't be vectorized readily when created. A photo is one such example. Raster file types include JPG, TIF, PSD, etc and are often compressed meaning that unnecessary information is discarded in an effort to reduce file size. All pictures posted here on RCU are JPG's or GIF's (less smart than JPG as it is indexed) so they are raster flavored. Raster files are comprised of colored pixel information at the resolution of the particular file. Pete's TIF plans come in this format and are compressed using a JPEG codec (I won't get into that though). Uncompressed TIF files are also possible which is what makes TIF (and TGA & PIC) a desirable raster file format. These files are better suited to scaling and produce excellent results when printed at their native resolution or smaller (e.g., inkjet photo printers). JPG files, by nature, are compressed - always.

On the other hand, vector based images are files that describe particular shapes via a scalable algorithm. For example a curve can be described via an equation and the file might say: "put a quarter curve using this formula at this location on the page". Because there is no intrinsic limiting resolution to vector images (a curve is a curve at any size), these files can be scaled to your heart's content without any loss in quality. Examples of vector based file types include PDF, PS, AI, etc. These are the ideal file format for working with plans as one often wants to scale them for printing or for reducing/enlarging a model's scale.

In a nutshell, a typical printed plans to computer to printed plans path might be something as follows:

[ul][*] Scan printed plans into raster TIF file - uncompressed if possible (full sized, 150 dpi or greater). Scanners don't know how to make vector files.[*] Convert the uncompressed TIF file into PDF (Acrobat Pro can be used for this).[*] Now that the file is vectorized, mark, stretch, squeeze, transform the plans at will. (Illustrator can be used for this.)[*] Produce final PDF file (or PS/AI if you prefer but PDF is the most portable and viewable) for printer. Laser printers (industrial large format) for printing at this scale typically speak Postscript (PS) so your PDF will be converted to PS upon printing (PDF and PS are close relatives). Inkjet plotters (corporate medium format) only speak a raster language so the vector PDF will be converted back to raster. The raster->vector->raster path is still a good idea even when printing on inkjet plotters. Kinko's probably uses laser printers at these scales (36" width)
[/ul]

End result - pristine plans tailored to your needs. In three words "PDF is King!"

If all this sound pedantic, my apologies. Just though it might shed some light on the subject.

Cheers, David.