Resizing and changing DPI of image easily

[macstatic]

I've scanned several documents at 300DPI grayscale and saved them as TIFF (to not get any quality loss), and want to make a PDF file out of it all (I use a free application called Combine PDFs for this).

However, the 17 pages I've scanned turn into a 28 MByte PDF file, which is wayyy too big, but I'm not sure what to resize and how in order to get a more acceptable size.

I've already cropped each TIFF file using Photoshop Elements 2.0, meaning they'll be of slightly different dimensions. Next, should I change the resolution or the DPI, or both?
And what's a good tool for batch changing things like this? Photoshop elements has a "batch conversion" feature, but it doesn't allow me to change the size in percentage, just pixels.

Then there's Graphic converter 5.9 which came bundled with my Mac. I know it has some pretty powerful batch conversion features, but it's not the easiest application to use and frankly those features are quite confusing.

So what should I do?
I'm aiming for a PDF with good quality for screen viewing, but also acceptable for printing if this doesn't mean very large PDF files.

 

[design-is]

For acceptable printing and screen viewing (not high quality printing, just acceptable) you should aim for probably 150dpi using medium jpg compression.

Try and save as a copy to test first - may even be able to go to low jpg compression dependent on the simplicity of your document, or may need high quality compression if you have complex graphics.

I haven't used PS Elements (or any of the other programs you mention), but I'd imagine one can do it for you even if you have to alter each image seperatey before re-PDF-ing. If you have access to Acrobat Professional, you can do it all from within the PDF itself, but not if you only have acrobat reader.

Hope I've been of some help...