Try opening up a PDF with the ColorSync Utility (in Applications -> Utilities) and notice how you can apply any colorsync filter and preview the results instantly. What this is really great for is reducing the size of PDF files with images for emailing. Example:
- Create a new filter by pressing the 'New' button.
- Click the 'Details' tab.
- Choose 'Images' in the top dropbox.
- Choose 'Compression' in next lower dropbox.
- Choose 'JPEG' in the last dropbox.
- Adjust the 'Quality' slider to desired compression.
- Check to 'Preview' check box and if you like the results click the 'Apply' button.
- Next go to the 'File' menu and click export and save as a new PDF or what ever type you want.
- Instead of choosing 'Compression' in the dropbox mentioned above choose 'Sampling'.
- Click the 'Down sample image:' check box and enter 50 for the 'Scale:' value.