Creating smaller PDF files

Among the many advantages of PDF files are that you can open them on any computer and they look just the way they were created - you don't need the original software which created the document, nor the fonts - and generally the file size of the PDF is smaller than the original. But not always. Sometimes, they come out bigger, which can be a frustration. This usually occurs because the document contains multiple images. Here are several tips to get the PDF file size down:
1. Images are often imported into the original larger than needed, and then scaled down. Unfortunately, all the original image information is still retained. So use an image editing program to resize the graphic before importing. Also consider reducing the resolution of the graphic. Any resolution greater than 225 dpi is unnecessarily high, and if the document is only going to be seen on a computer (ie, it won't be printed), then a resolution as low as 72 dpi is probably adequate.
2. Images are often also cropped when they are imported into the document. Crop before importing and you will save a lot.
3. When you export or save the file as a PDF, check the compression. For many purposes, medium or even low compression values will be adequate, making a huge difference in file size.
4. Another way to reduce file sizes is to do a "Save As" of the original document before making the PDF. This purges unneeded information which otherwise keeps getting added to the document but is not deleted. (For instance, all those changes you make while editing the document are actually held in the file, unseen but clogging up the document.)
5. If you're making a PDF for the Web and/or if you're not concerned about printing colors, use the RGB color space. RGB has one less data channel than CMYK, so your files will be that much smaller.
6. Embedded fonts also take up space, so keep the number of fonts to a minimum.
All that being said, you may be saddled with a PDF made by someone else (as happened to me this week), and you want to reduce the file size. There are numerous programs that can edit PDF files, the best-known being Adobe Acrobat. But that's very expensive. PDFill PDF Editor comes out a lot cheaper, but it's still commercial software. Fortunately, from the same stable comes a tool that did the job for me nicely. PDFill Writer is a free print driver that has a lot of options when saving the file. Once it was installed, I opened the over-sized PDF file, hit the Print button, and chose PDFill Writer as the print driver. It gave me a lot of options for recompressing the graphics, and voila! a 25% saving in size. Another free tool at the site is PDFill Tools, which allows you to do interesting things like split PDF documents, and merge several PDF files.