Line drawing bleeding color into background

[Becky Cleland]

I use Photoshop to create graphics for the library I work in. I used it to make a floorplan of the library--a line drawing of black on a white background. It looks great when I first save it. Trouble is, when I come back to it, it has become "dirty;" tones of grey have bled into the background , especially around the corners and intersections of lines. It takes huge amounts of time to clean up the "dirt." What can I do to prevent/correct this? MOST grateful for assistance.

[BLUDVLZ]

How are you saving this file? My guess is as a JPEG or GIF.

Save as a TIFF file instead, and use the Bitmap color space instead of grayscale (if you want true lineart images, of course).

[barry gray]

Does the "dirt" print? No? Is it visible when viewed at 100%?

[Carl B. Johnson]

Becky

What rez are you creating/saving at? For line art 1000 DPI is best.