[MacNNUK]

Open PDF in Preview (3.0.9) (default on my iMac) under 10.4.11 on my iMac

Select Print, using Copies & Pages drop down, select Color Sync drop down.

Under Quartz Filter, select "Reduce File Size" drop down

PDF, "Save as PDF"

With many graphics heavy PDF's, this will reduce file size, one of mine went down from 5.6mb to 52kb !
(Originally Word ... Home Made Calendar doc saved as PDF)

Really useful...I used Spotlight to find .pdf's, then sorted by filesize, viewing as list

I reduced a folder containing many PDF's from 188mb down to 148mb in a few minutes. This folder I backup copy to CD every two weeks, so size matters.

As yet I have not noticed any reduction in quality. Except when I test saved a JPG opened in Preview, and saved as PDF reduced file size, but then it did reduce from JPG@572kb down to PDF@40kb! See below.......(These are screen captures, shown here as JPG's in order to view)

Check new filesize, in some instance it may be more than the original.

I would show an example of a PDF original reduced to smaller file, but I gives away too much personal information.


So, does not work in every case.

Here's the Apple Video.....


Apple - Small Business - Quick Tip of the Week

572kb JPG


40kb JPG screen capture from PDF

[Don Pickett]

Using a JPEG to illustrate this isn't the best choice, as JPEG was made, from the beginning, to be compressed.

Basically, you will only notice PDF compression on the upper and lower end of the spectrum. In other words, so long as the image isn't meant to be professionally printed, reducing the resolution (and, thus file size) from 300 dpi to 200 dpi won't produce a difference noticeable to most people. A 200 dpi image will look just fine printed from a color laser printer, as will a 150 dpi image. And, since changing file size is geometric (doubling image resolution increases size by a factor of four) reducing from 300 dpi to 150 dpi saves you a lot of space. For most non-professional purposes you won't see a noticeable lack of quality until the resolution of the images drops below 100 dpi.

The same is true on the other end, which is generally only used for professional printing. A PDF output using Acrobat's press ready settings will give you a large file, as the images aren't compressed much, if at all. At that size PDF is more of a packaging mechanism and not a compression and packaging mechanism. However, outputting a PDF with too low a quality on an imagesetter or other high resolution device will result in unacceptable output.

[MacNNUK]

Originally Posted by Don Pickett 

Using a JPEG to illustrate this isn't the best choice, as JPEG was made, from the beginning, to be compressed.

I understand that, and I would not normally previously use Preview to reduce file size on a JPG, what the images show----- perhaps I needed to explain a bit more, was that the file reduced image was actually a JPG, saved as PDF reduced file size, then PDF image was screen captured using --- Up  4 --- in order to display a somewhat reduced file size, as seen on screen, if that is understandable.

I didn't explain that, as I thought it would only confuse the issue.

So the comparison is in reality screen captures, ie as seen on screen.


Having said that, I have also started using Preview to reduce JPG file sizes on non important JPG's, ie for reference only, such as council works outside my house, etc, and find it ok, whereas before I used to use Graphics Convertor, OK, but a bit more long winded, for JPG's I may never look at again.

I use Preview in a slightly different manner to do this, save as JPEG, with user defined quality. I do not save the JPG's as reduced file size PDF's.

As here: http://forums.macnn.com/82/applicati...age-file-size/

Originally Posted by Don Pickett 

Basically, you will only notice PDF compression on the upper and lower end of the spectrum. In other words, so long as the image isn't meant to be professionally printed, reducing the resolution (and, thus file size) from 300 dpi to 200 dpi won't produce a difference noticeable to most people. A 200 dpi image will look just fine printed from a color laser printer, as will a 150 dpi image. And, since changing file size is geometric (doubling image resolution increases size by a factor of four) reducing from 300 dpi to 150 dpi saves you a lot of space. For most non-professional purposes you won't see a noticeable lack of quality until the resolution of the images drops below 100 dpi.

The same is true on the other end, which is generally only used for professional printing. A PDF output using Acrobat's press ready settings will give you a large file, as the images aren't compressed much, if at all. At that size PDF is more of a packaging mechanism and not a compression and packaging mechanism. However, outputting a PDF with too low a quality on an imagesetter or other high resolution device will result in unacceptable output.

That's a really good explanation, I wondered how it worked.

As before, I keep a lot of PDF's, (non-professional) either initially downloaded as PDF's, or other items saved as PDF's, using Preview, again for reference, and I had a great time for an hour or so reducing my PDF and other information folder way down.

Strange how some PDF's reduced were approx similar size, and one or two were increased in size!

No doubt a good explanation for that too.