For black and white images in technical manuals, which format do you prefer?

> ... 90% of the manuals are digital (burned into a CD)

Presumably as PDFs, which the ends users then either view on line or print locally?

> ... and 10% are printed in grayscale.

On what type of press?

You probably want the images optimized for on-line viewing.

In the case of line art, this means staying in vector form, so that it scales cleanly, and using a stroke weight that is optimized for typical resolutions and convenience printing.

In the case of raster art, this means having enough resolution to maintain detail at reasonable zoom, and on convenience printers.

For vector, we normalize stroke weights to about 0.2 point, save as EPS and import the EPS. On Frame versions later than 7.x, PDF import might also be stable, and preserves vector as vector. SVG I haven't tested.

For raster contone (grayscale or color), avoid JPEG in the workflow. It is lossy and introduces artifacts. Never use it for screen shots or scans. Even if your camera image is JPG, convert it to an uncompressed form during edit and post-processing, such as PSD. Our target delivery resolution for contone is 200 dpi. This is slightly more than our press can resolve, but provides a bit of zoom for PDF viewing. We save the final images as EPS, and import those. TIF is also OK for this application (uncompressed). We select the compression level during PDF generation.

For bitmap images, again avoid JPG. We optimize these for 600 dpi (our press resolution), save and import them as TIF (EPS is really clumsy for bitmap).

EPS is a bit annoying to work with in Frame, as what you see during edit is a thumbnail or preview (72 dpi), but what renders to Ps or PDF is original vector or full raster. But EPS is fast, rock solid, and (if you need it) can preserve original CMYK color into the Ps or PDF.