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"Reduce File Size..." Resolution concerns

stevec1007
Registered: Jun 18 2008
Posts: 5
Answered

Help?
I have some rather large pdf files for print production. I have been choosing "Reduce File Size..." to make my files easier to send to the printer. Things have been fine as far as resolution, but now an image has shown up looking lo-res. Should I NOT use the Reduce File Size menu option? Does it really reduce the resolution as well as the size? Some of my jobs look great so now I am concerned. Can anyone help with this? the docs from Adobe seem vague. Thank you in advance for helping!
Steve

My Product Information:
Acrobat Pro 8.1.2, Macintosh
daka630
Expert
Registered: Mar 1 2007
Posts: 1420
While I am not sure of this, I suspect that the "Reduce File Size..." option is, in some way, using PDF Optimizer as the feature's dialog describes saving to an earlier PDF version.

If you process your PDF files with PDF Optimizer you will have a plethora of configuration settings available for images and other aspects of the PDF file(s). The Acrobat Help provides discussion on using PDF Optimizer.

The Standard, out-of-the-box, setting uses downsampling and JPEG compression for any images in the PDF.
If "Reduce File Size..." pulls from this then image degradation would be expected.

The degradation may or may not be readily noticable. Regardless, downsample removes pixels and JPEG compression is a lossy vice lossless compression mechanism.
These can adversely impact the effective resolution of your image which can adversely impact what you "see".

Be well...

Be well...

stevec1007
Registered: Jun 18 2008
Posts: 5
Thanks, I think you are correct. I also did some tests turning "Reduce File Size" on and off. There is some resolution loss although it affects some images more than others. To be on the safe side I will not use it until I figure out the PDF Optimizer! Thank you again.

daka630 wrote:
While I am not sure of this, I suspect that the "Reduce File Size..." option is, in some way, using PDF Optimizer as the feature's dialog describes saving to an earlier PDF version.If you process your PDF files with PDF Optimizer you will have a plethora of configuration settings available for images and other aspects of the PDF file(s). The Acrobat Help provides discussion on using PDF Optimizer.

The Standard, out-of-the-box, setting uses downsampling and JPEG compression for any images in the PDF.
If "Reduce File Size..." pulls from this then image degradation would be expected.

The degradation may or may not be readily noticable. Regardless, downsample removes pixels and JPEG compression is a lossy vice lossless compression mechanism.
These can adversely impact the effective resolution of your image which can adversely impact what you "see".

Be well...
tplumer
Expert
Registered: Dec 1 2005
Posts: 122
daka630 is correct.

In general, you remove information (by down-sampling and compressing images) when you reduce file size. Press-Ready PDF files are often quite large, and reducing the file's size is not recommended (by most printers I know of). Reduce File Size is the younger sibling of the PDF Optimizer, and just takes a good hearty swing at reducing the file's size. You should never use this for press-ready PDF files (or images in a print project in general).

Discuss PDF setting with your print vendor, create PDF files to those settings, and then bear with the file's size.

I am a long-time Acrobat user, an employee of Adobe Systems, and Maine native. I have created training videos for Total Training, consulted with people to help them better use Acrobat, and developed new business for Adobe as a Business Development Manager

stevec1007
Registered: Jun 18 2008
Posts: 5
Thanks for weighing in! I've learned my lesson!
isaanderson
Registered: Aug 11 2008
Posts: 72
Create a custom pdf optimizer settings. I made one and it's been great for reducing the file size and there is not noticeable loss resolution. Do this:
1. Open a file in acrobat
2. File> pdf optimizer
3. Under "images" Choose: average downsampling 300 ppi, compression jpeg "maximum" Do this for grayscale and color images. Under monochrome images pick the same but choose CCITT group 4 for the compression
4.Under "transparency" choose "high resolution"
5. Under "discard objects" check all the boxes
6.Under "discard user data" check all the boxes
7.Under "clean up" choose "make compatible with acrobat 5 and later, "compress document structure" and check all the boxes again.
8. Click the "save" button on the top of the window
9. Give these settings a name (mine is called jpeg300)

Next time you have a HUGE pdf file, optimize it using your saved settings and it will significantly reduce the file size. I've done a lot of print marketing materials this way and my printer has no problem with my files and I have not noticed any significant loss of resolution.
elenaluzz
Registered: Dec 1 2009
Posts: 1
I do have "print ready" documents I need to send out to customers, but they are so big they are hard to handle by my (or their) outlook or email program. Zipping doesn't seem to be an option, and I've tried using my cloud database platform (salesforce.com) to send them, with spotty results. Any suggestions to make my pretty 1meg+ documents more manageable?
Thanks!