I am designing covers for books which need to be printed at an exact size. I set the size of my object using the Geometry Inspector, for example… a 7x9 rectangle. I can measure the object on my screen with the screen size set to 100%. Indeed, the rectangle is 7x9.
I need to send the document to a commercial office print shop located in town. I send my project as a .pdf which I create with Preview on my MacBook Air. I export it using a quartz filter that allows me to reduce the file size.
I have never had a cover print true to the size I see on Omnigrafffle. Usually, it is the height that is off. It seems to be off by half an inch in most cases. (I know, I should have been keeping records… but, I haven’t.).
Any thoughts? This shouldn’t be hard… I want a 5x7 to print true to size.
There are a few minor things getting in the way of your desired results. First is the quartz filter. I looked into how it works, and it reduces file size by shrinking your PDF without regard to the image quality and it sets the page size maximum to 512 pixels, so you want to discontinue use of that for any purpose other than a preview. It will make your graphic too low a quality to print in most cases. If the PDF files being too large are an issue, consider using some kind of cloud provider like iCloud or Dropbox to send your larger documents to the printer.
The second issue is with OmniGraffle and the way pages are defined. Because it sounds like you are printing with bleeds, you likely want to use a fixed page size instead of letting page settings that may have printer margins define your page size. Here is an example document that has settings you could use: 7by9Portrait.graffle (19.1 KB). Importantly, the units have a * at the end, so are one of the scales that prints true to size at 100% page scale, as shown in this screenshot.
When you check the size of the graphics in the Geometry Inspector, and then you export to PDF at 100%, you get a 7" by 9" inches actual size image. You can check that in Preview by going to Tools>Show Inspector. There the page size should be showing at 7" by 9". Check the page size in Preview before running the filter on the PDF, and only run the filter on a copy of the PDF so that you can compare. If the page size is different after running the filter, you can be certain that is the cause of the size difference.
If you are still running into any inconsistency, feel free to send us an example document from Contact Omni in the help menu. We’d be glad to work with you to make sure you get the right results.
They might have been correct that there is no loss of quality, but that is for images up to 512 pixels, so there are limitations. For smaller PDF files and for screenshots, what they said is still true, so the filter may still be useful to you in other situations. It is also possible to go into the quartz filter and see the settings for yourself. There’s some information about doing that at http://hints.macworld.com/article.php?story=20120629091437274 that might help you see which settings are used.
