Using Acrobat 5.0, we’re creating pdf versions of engineering drawings for our released copy archive. Most are output to Acrobat from several CAD apps, but some are scanned hand-drawn vellums. We scan the 11x17 B-size on an old Ricoh IS410 bed scanner inputting CFM-Twain at 300 dpi in scanmode halftone set to error diffusion. The resulting pdf files (single sheets) are coming out at 2MB and 3MB, which is unacceptable with the number of files we have to store. How can we do this and get smaller files with a decent image? --Bob Wilkinson

Your solution *might* be a bitmap to vector conversion program - I use CorelTRACE but I'm sure there are others to choose from. The results vary greatly depending on the type of image you are working on, but if your originals are line drawings, you may find that the results are suitable. –Gary

Get a free copy of Paint Shop Pro ( PSP) here. In PSP save in JPEG (JPG) format not PICT or BMP:

File > Save As... > Save as type > JPG - JPEG - JFIF compliant. A 1000KB photo can be reduced to close to 100 KB. Also try cropping the image to get rid of unimportant parts:

Image > Crop

Reducing the image size by a half reduces the file size by a quarter and customers may zoom in Acrobat Reader. –Malcolm Macgregor

Here's how I would get there. I saved a 12 x 18 grayscale image as a tiff (18.7 mb). On Windows, and using Acrobat 6.0.1 with the highest quality job options, I simply right clicked the tiff file and used the Convert to PDF command. The PDF file size at 300 dpi resolution was 371 kb, a file size reduction of over 95%. It could be possible to reduce the file size even more by fooling around with the compression settings in the Distiller job options.

P.S. You should upgrade to Acrobat 6.X and instruct your service provider to do the same, if they haven't. --Rich Sprague

You should try our PDF compressor. It should significantly reduce the size of the scanned images, without loss in quality. I don't know about the exact compression ratio but we have a number of clients who scan CAD images and use us to compress them. There is a demo version here. –Max, CVISION Technologies

Just for kicks, I downloaded the [CVISION] demo version and converted the same tiff as before (this is a grayscale image, by the way). I wasn't impressed. The file size came out to be 478 kb...larger than what Acrobat did on its own. Acrobat 6 has a built in PDF compressor, which I then applied to my original file (which was 372 kb). I choose the medium settings (150 dpi). The file size reduced to 109 kb. This is like a 99% compression rate. I would guess that images which have more white pixels than the image I selected would even be smaller. PDF Compressor costs $300 or so. The Acrobat upgrade to 6.0 is quite a bit less: $149 for the professional version; and $99 for the standard. --Rich Sprague

Good advice. You can use Paint Shop Pro to do this kind of thing as well, at lower cost (i.e. free). – Paul Baker

This isn't grayscale. Halftone with error diffusion is an algorithm of converting a color space to bitonal, which is done by practically all the scanners. Try: http://www.google.com/search?sourceid=mozclient&ie=utf-8&oe=utf-8&q=halftone+error+diffusion  . So the actual image Bob is dealing with is bitonal. I ran Acrobat with optimizer on a few halftone CAD drawings from my database. It produces compression rates similar to PDF compressor, but runs almost 5 times slower, which may be significant to the customer. Acrobat is a great program, but if all you want is conversion from image and/or PDF compression, PDFCompressor Desktop is a reasonable choice. –Max, CVISION Technologies

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