Quality of PDF when viewed in Preview 4.1

L

loelie

Registered
Hi

I have created a PDF using Acrobat Professional, to make the size of the PDF smaller I made the program reduce the size a little, which when you watch it in Adobe reader does not seem to have any affect to the quality of the picture in the PDF. However, when you watch in Preview 4.1 there is a huge difference in the quality. This is a problem, because when I send out this PDF I have no control over what program the clients will use.
Does anyone have any explanation to why this has happened???
I would have thought there would be no difference. I must note that when you watch the PDF without reducing the size in Preview, the quality is fine!
Another question is: what is the best way to reduce the size of a PDF, when the quality of the images in the PDF should be high???
Thank you!
 
Preview doesn't use the same PDF engine to display PDFs. You won't have complete control over how a PDF looks on a client's computer. (But at least it looks a lot closer from computer to computer than when using any other format.)

But keep in mind: Whenever you "reduce size" in a PDF, you _will_ lose quality. There's no way around it, because the most space can be gained by reducing the JPEG quality of images in the PDF.

Oh and: Don't post questions to the HOWTO & FAQs forum. Read forum descriptions _before_ creating threads. Just because a question is important to you, it doesn't make it a "Frequently Asked Questions". Both the term "HOWTO" and the term "FAQ" describe guides that already contain answers.
 
Well.... the things in a pdf that make the file large _are_ the images - the text and any vector stuff uses minimalspace. Reducing PDF file size pretty much means reducing image quality.

What you can do though is ensure that as much as possible of your pdf is based on vector graphics.

For the images if they will be basically only read onscreen then you can reduce to 72dpi which is screen rez (for decent printing you need 250-300 dpi). Also, compression works more effectively on images that are not too varied in colour - if you have a shot of a person try and do it agaisnt a solid colour background, it will compress more with less loss of quality.

Not sure why preview looks different to acrobat - maybe try using different pdf versions, I believe that preview uses an older version (1.4 or soemthing than acrobat (which uses more like 1.7 if i recall correctly)
 
Thank for replying and sorry about placing this the wrong place is new to this forum.

The JPGs in the pdf is 72dpi and saved as a quality 10, so they are already quite small. I just do not understand why there is such a huge difference in quality from Preview to Adobe Reader. The front page which is only writing is the worst. :confused:

Anyway thank you!!
 
If it's only writing, i.e. actual _TEXT_, should not look worse at all. Unless it's actually a picture of text, which would be the wrong way to go completely.
 
loelie said:
...

The JPGs in the pdf is 72dpi and saved as a quality 10, so they are already quite small. I just do not understand why there is such a huge difference in quality from Preview to Adobe Reader. The front page which is only writing is the worst. :confused:

...
Click to expand...
FWIW, 72 dpi graphics is low-quality irrespective of how minimal the compression. It might be useful to give your source--application and file types--of the graphics and text in your PDF. For example, if you scanned-in your text, then you have a picture of text and not text itself. There are occasions when scanning text is necessary. On such occasions, you should scan at a resolution of at least 300 dpi.

Text in raster images is problematic under the best of circumstances. Whenever I have text in a scanned image or a raster image from some other source, I try to erase the text image and then replace it with a replicated text layout in a vector format.
 
You must log in or register to reply here.
Back
Top