G'day mahi,
I created those manuals back in 2003 and 2006, so I'm relying on my memory here. I’m no expert at this manual scanning stuff, however, I’ll try to fill you in on what has worked for me. These manuals were my first attempts at scanning paper manuals and converting to PDF files. I had to make do with a cheap parallel port scanner a friend of mine gave me after my old HP SCSI scanner cashed its chips in, although I have to admit, this parallel port piece of junk performed a fair amount of work before it too eventually entered into a state of rigor mortis. I’ve been reluctant to buy another quality unit as I’ve been trying to find a good, not too expensive A3 scanner. The software supplied with that parallel port scanner was so flaky, it barely ran on XP at the time without crashing, even requiring Windows re-starts when it locked up. I must've had the patience of Job to get through both manuals at that time.
I used the scanner software to create individual monochrome BMP images with the exception of the colour cover for the 93-95-97 Service Manual, which I'll address later. I did not use "Grey Scale" or whatever the scanner software may call it, instead opting for "Line Art, Black & White or Monochrome," again, whatever your software terms it. These "Line Art" images are considerably smaller than "Grey Scale" ones which will ultimately result in a smaller PDF file after conversion later. The drawback with "Line Art" images is that if your pages have photos or shaded schematics, for example, the shading may come out very light or even very dark, whereas pictures or photos will be pretty poor quality depending on how the shading or photo was originally printed. I scanned the pages at 400 dpi or even 300 dpi to further keep the BMP image relatively small. (I found no discernable difference between 300 and 400 dots per inch with this particular scanner). I also noticed that even "Colour" scanned images ended up being smaller than the "Grey Scale" ones at the same resolution with that parallel port piece of junk. Another plus with "Line Art" scans is the fact that the text on the other side of the page doesn’t show up through the page, particularly with thin pages. I never save the scanned image as a JPG because the file becomes a large PDF file after conversion. I know that sounds odd, however, PDF conversion from a larger BMP file resulted in a smaller PDF file with the method I used - there are exceptions, of course. If you do have colour schematic pages to scan, one option is to save them as colour BMP files, however, choose 256 or even 16 colours to keep the individual file sizes small to allow for smaller PDF files after conversion.
I used Adobe Photoshop to edit the individual BMP scans. You’ve probably noticed that there are no binder ring-hole dots on the pages of the manuals as I’ve removed them. It’s relatively quick and simple to remove these or other lines, imperfections and such, straight after each page is scanned, before saving the scanned BMP image through Photoshop as individual PDF files. I then opened the first page with Acrobat 7 and then insert all the pages to make up the manual. Bookmarks were added after the manual was compiled. I performed OCR on the compiled pages and selected "Reduce File Size" in Adobe Acrobat to arrive at a rather small PDF manual at around 10 MBs.
Regarding the colour cover of the 93-95-97 Service Manual, the scanned colour BMP image is just over 100 MBs. Directly converting this colour BMP image to PDF with Adobe Acrobat 9 results in a PDF file size of 1.15 MBs. Selecting "Reduce File Size" from the Toolbar Menu results in a file size of 194 KBs, a far cry from the original colour BMP scan of 100+ MBs.
There are probably other simpler ways around this whole process, however, I haven’t experimented with them. I tend to get used to doing something a certain way and then sticking with that. Maybe I was taking a "shortcut" by travelling from Chicago to Detroit via Mexico City, but it worked for me at the time. There are other PDF creation programs out there; QuarkXPress is one that comes to mind, however, I’ve had no experience with it, so I can’t tell you anything about it.
I hope this helps, kind regards,
Tom