Quality reduced file size in Mac OS X Preview
ColorSync makes Quartz filters.
If you use the print to PDF feature in Mac OS X, you have probably noticed that it can create some really large PDF files. This is fine as long as you are copying them to CD or DVD, but if you’re putting them on the web or sending them through e-mail, they can really cause havoc on both ends.
If you open the PDF in Preview, you can reduce the file size by doing a “Save As...” and choosing, appropriately, Reduce File Size from the Quartz Filter menu. Often, that will be fine. But the way that it reduces the file size is by saving all images as JPEGs of middle quality. Sometimes that quality will not be enough.
I just finished a Persistence of Vision tutorial, and because it’s a tutorial on using a 3-D raytracer it was full of images. The PDF file was nearly 20 megabytes. After saving it with Reduce File Size, it was down to under one megabyte... but the quality of the images was so bad that they didn’t serve to illustrate the concepts in the text.
It was obvious what was happening, and I knew that when saving JPEG files you are allowed to trade off low file size with increased quality. But there was no slider available in the Quartz Filter menu to increase the quality of the image.
The answer, it turns out, is in ColorSync Utility in the Utilities folder off of the Applications folder. ColorSync Utility can create new Quartz filters. Open up ColorSync Utility and switch to the “Filters” pane. This will list all of the filters that you currently have available.
- In the lower left, click on the “+” button. This creates a new filter.
- Give the filter a name, and press return.
- To the right of the filter’s name, choose the down arrow. A menu will pop up.
- From the pop-up menu, choose “Add Image Effects Component”, and from that menu choose “Image Compression”.
- Adjust the image compression Mode to JPEG.
- Adjust the image compression quality however you prefer.
- The next time you use Preview to “Save As...”, you'll have a new option under Quartz filters.
I’ve created a Reduced File Size High Quality and Mid-Quality as custom Quartz filters.
With the quality slider three quarters over, the file size dropped to 7.7 megabytes. This is quite a bit larger than with the slider half-way over, but not nearly the 20 megabytes of the original. And quality became a lot higher.
Filter while printing
You can also filter while printing, avoiding the need to re-open the PDF in Preview. When you go to print, pull down the menu just below “Presets” that usually says “Copies & Pages”. Choose “ColorSync”. Then choose the Quartz filter that you want. Once you’ve chosen it, you can also pull down the Presets menu and do a “Save As...” to remember these settings.
- Persistence of Vision tutorial
- A step-by-step tutorial, available under the Gnu Free Documentation License, on using the Persistence of Vision raytracer.
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