Emailing PDF proofs to clients is really convenient, as long as you can keep the overall file size under control. For most InDesign documents, this is as easy as selecting the “smallest file size” preset in the PDF export dialogue box, but for some projects, even “smallest file size” will result in ridiculous file sizes. This is especially true when the entire background of a file is a giant photoshop image. InDesign needs to chew through that whole placed file to properly render a PDF, and the result is a file size that will make your email client break out in a cold sweat.

Here’s a quick work around that will help when all else fails, and you’re still left with double digit megabyte file sizes on your PDF.

(Note…this works best for posters and other one-page InDesign files, or for individual pages in large page count documents that might be giving you trouble because they have a lot of images information, or transparency information.)

Basically, what we’re going to do is make a full-size high resolution image of the whole page of content. This will retain the detail we need to make a clear PDF, but it will “flatten” out all of the extra information on the page that complicates the PDF creation and increases the file size. Then we’ll use this image to create a much simpler PDF.

Once you’re finished with your design, export it as a PDF from InDesign. (In the file menu, click “Export,” then specify where you want the PDF to be created. I generally put it on the desktop).

Make sure to set the export preset to “PDF/X-1a:2001″ from the preset pull down menu at the top.

Click “Export.” InDesign will churn through your file and burn a high resolution PDF on the desktop (or wherever you specified the file to save).

Let Photoshop do the Heavy Lifting.

Once the file is created, open Photoshop and go to File>Open and select the PDF. In the dialogue box, make sure the resolution is set to 300 dpi. Don’t change the height and width dimensions. Now click “okay.” (You can only do one page at a time, so make sure you’ve selected the page that you want to process). Photoshop will work for awhile and eventually open a full-size, 300 dpi version of the PDF as a new image file. Click on Layer>Flatten Image and then save this as a .tiff or a .psd file somewhere handy.

Back to InDesign

Create a new page in your original InDesign document and place your newly created image file in this new page. If you line up the upper left corner of the image with the upper left corner of the page, the image should fit the entire page perfectly.

Now, go to File>Export and create a brand new “Smallest File Size” PDF of the new page only. The result is a PDF with all of the page information at a dramatically smaller file size. Happy emailing.

Still too large?

If you’re just sending the PDF for proof, you can also reduce the resolution in your PSD to 72dpi. As long as you don’t change the Height and Width dimensions, and as long as you do not resize the image once it is placed in InDesign, “Smallest File Size” export should still result in a good quality final PDF and drastically reduced file size.

Some Things to be Aware of

If you have “paper” in your InDesign file (by which I mean areas of “white” on the screen preview that represent areas of the final print where no ink would be laid down on the paper), Photoshop will treat these areas as transparent. Flattening the image will take care of this.

Update

I work at Notre Dame and, as such, every couple of weeks I need to deliver an advertisement for placement in the student newspaper the Observer. Usually I submit PDFs, but this turns into an absolute crap shoot because the Observer’s ad department has, apparently no qualms whatsoever about printing ads with missing font information or (at times) all of the fonts replaced by dots and dashes reminiscent of morse code. (I’m not making any of this up).

Recently I’ve started using the above technique to lock down the ad before it leaves my computer. The logic being: “If the ad ain’t got no fonts…the Observer can’t print my design with bad fonts or no fonts at all).