Walt wrote:
> If you want 300 ppi resolution of your (bitmap) images, they must be 300 when you insert them. For the vector parts, resolution is immaterial. That's not hard.
Actually, it is.
1. To check the resolution of a TIFF or JPEG file (one image, one file), start Apple Preview and select Tools > Get Info. This will show the resolution, the colourant format (RGB, CMY, CMYK ...), the colourimetry specification (either unspecified deviceColor or specified by ICC source profile).
2. To check the resolution of a PDF or EPS file (one or more images and other objects, one file), there is no human interface in Mac OS X that lets you look at the object-oriented metainformation. You have to have third party software, and you have to have a working knowledge of the Adobe imaging architecture.
As I wrote above in this thread, it is not correct that the ColorSync Utility will always render transparency resolution at 72dpi. Transparency was introduced in Mac OS 7.5 for QuickDraw GX in 1994 and reintroduced in Mac OS X for Quartz in 2000, so it's nothing new in the screen imaging system.
However, getting from the programming operators for resolution-independent transparency in the screen imaging system to the resolution-dependency of a RIP using the Adobe imaging architecture has been a problem for eighteen years, which is a little short of the time I've spent writing in this neck of the IT woods.
PDF/X-4 supports live transparency (and layers), but a test in 2012 suggested that there is still trouble sorting out how live transparency should be rendered. PDF/X-3 does not support live transparency: you have to pre-render to the resolution of the intended printing condition (which you have to know, of course).
Finally, if you choose the PDF/X filter in the ColorSync Utility, you are informing the system that you want to save a ColorWorld complete with the ICC profile for the intended printing condition. Here you have to know what that profile is, which may or may not be the default profile offered by the default filter.
The current default profile came about after an argument between the ColorSync Users List and ColorSync engineering. On the List, we wanted a change from a default profile for the Apple Color LaserWriter to a default profile for a genuinely common printing condition.
Apple engineering then chose US SWOP as the common printing condition to which new drawing in CMYK mode as well as unmarked/untagged drawing in CMYK and drawing in CMYK mode for PDF/X would conform. However, what you buy when you buy print is by and large gamut, so if you are buying print, check if the gamut you are buying is bigger than the gamut of US SWOP, because if you send the printer PDF/X with US SWOP as OutputIntent, you have declared that you want to reduce the gamut to US SWOP regardless of the gamut the printer is offering you.
It's like choosing to write in 7-bit US ASCII = the Basic Latin Block of ISO-IEC 10646. The size of the input writing space determines what you can send, irrespective of the size of the reference/connection space and the size of the receiving/output space. You can't write Russian, because Cyrillic is far out of gamut for US ASCII. This is simple set theory, and the gamut comparison in the ColorSync Utility can be used to check the size of the writing/working space relative to the size of the space for which you select a receiving/output profile in the ColorSync Utility.
Hope this helps,
Henrik