Saving a high res PDF to a workable size without losing resolution

I took a Word doc, converted it to a high res PDF, then converted it to CMYK in PS. Because it is for a booklet and I have 100 pages, I then placed the pages in ID. Whe开发者_JAVA百科n I saved it to a high res PDF my file is now 750MB. How do I save a high res PDF for print production to a manageable size with out losing my resolution.

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First, this entire Q&A belongs not on StackOverflow, which is for programming questions, but instead probably on Superuser.

Anyway, to answer your question: You don't.

Print production demands high resolution, compared to web or screen media. Typically a printed piece is printed using a halftone of about 150 to 300 lines per inch. (That's lines of halftone dots, not pixels or the dots that make up the halftone cells. 150 is typical for most printed items, 200 and up for art books and finer products.) To create a printed image without noticeable pixelization or degradation, you want about 1.5 times the pixel resolution of the halftone screen. (See Adobe, Quark, or Corel print guides for this technical info.) This means you need an image of about 300 ppi (pixels per inch) when printing using a 150 line screen. Note that's 300 ppi unscaled. So placing a small image that's 300 pixels square and stretching it to two inches square won't work; it's only 150 ppi when it gets imaged on the press plate.

CMYK images are 8-bits for each of four channels. An 8x10 "full page" image is 7.2 million pixels. 7.2 million times 8 bits times 4 = 230.4 million bits, or 28.8 megabytes. If you have such an image on every page of a 100 page document, the entire file should come in around a whopping 2800 MB. Thanks to compression, and the fact that you probably don't have a large image on every page, it is much smaller.

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The solution to your problem will be with how you do the different steps. Converting from Word and then to images in Photoshop is likely not the best way to do things.

If you simply want to use this Word document as is, save it as PDF. This will be a somewhat "challenged" PDF file for graphic arts because Word will give you something that is likely sRGB. Instead of using Photoshop, use a tool such as pdfToolbox (I'm associated with this company), Adobe Acrobat, PitStop or similar to convert the PDF from sRGB into CMYK. The tool should be able to do this without rasterising anything that isn't already an image in the Word file.

If you want to make a booklet out of this, look at a tool that can do this in PDF; pdfToolbox again or something like Quite Imposing. Again your booklet will be created without ruining quality of anything that is in the file already.

If it sounds like a convoluted way to do things, yeah, that's correct. But coming from a tool like Word, you'll need some steps to get to a correct file. It's easier if you start out in InDesign of course.