Manual scanning: TIFF-to-PDF software with greyscale support?

Hi guys, I'm after a program that can convert TIFF files into PDFs. I've seen Eric Smith's "Tumble" app, which works great... but only for B&W TIFFs. While I can use Imagemagick to convert the images to B&W, that defeats the point: there are photos on the scanned pages, and I'd rather like to keep them as photos, not black splodges. Also, has anyone come up with a "best practice guide" for manual scanning? At the moment I'm scanning like this: B&W text only: 600dpi, black and white, threshold=50%. Text + photos: 600dpi, greyscale, then despeckle and scale down to 300dpi. Obviously if there are better ways (in terms of quality and/or speed) I'd like to know before I scan a ton of testgear manuals... Also, does anyone know of an app that can take the PDF file, OCR it and then insert the text as a background layer while leaving the image alone? I'm pretty sure Acrobat can do this, but like most Adobe software, the price tag is somewhat... eye-watering. "If you have to ask how much it costs, you can't afford it." Thanks, -- Phil. classiccmp at philpem.me.uk http://www.philpem.me.uk/