Compression PDFs

[defaults34jld5w0219]

By compressing a file of 1.20 mb ('Medium Compression' option) with the online version Acrobat Tools it becomes 420 Kb, while with my Acrobat Pro Desktop version it becomes 1.01 mb.
Why?

[Bernd Alheit]

What options does you use in Acrobat?

[JR Boulay · Accepted solution]

Certainly because these two tools do not use the same compression parameters.

[defaults34jld5w0219]

Ok, I understood this but what are the settings for the 'medium compression' options? I've tried everything but it doesn't work for me.

is this the configuration panel?

thanks

[Test Screen Name]

There is no simple rule of PDF compression. "Medium" isn't a standard thing, it's just what one app chooses to do. You need to play with Acrobat's settings. Tip: Audit Space Usage will be your main tool.

[GoGayleGo]

I kind of have the same question as the OP.  I understand your response that the two tools don't have the same compression parameters.  I have Acrobat X.  I have compressed a ~6MB file using the Acrobat online tool (as a one-off, as I don't have the paid cloud version).  I used Medium and Highest compression, resulting in files of 2.3 MD and 268 kB.  When I use Save As Reduced, or Optimized through Acrobat X, I get literally no reduction of filesize.  While the compression parameters may not be exactly the same, I can't imagine they are that wildly different.  Is there a way in Adobe X to emulate the compressions done via the online tool?

[JR Boulay]

Never, never, never downsample images to 72 dpi!

It corresponds to the resolution of old cathode ray screens and it is therefore completely obsolete since current screens are rarely less than 110/120 dpi and some exceed 500 dpi.

You should not use a value lower than 200 dpi. Knowing that it is more the compression rate which reduces the size of a file than the downsampling.

[Test Screen Name]

"Never, never, never downsample images to 72 dpi!" Well, it depends what you want. If I want a rough layout I go down to 50 ppi or less. Also, for photos (not screen shots) it's a myth that you can only get acceptable results if image resolution is at least screen resolution. Try it! 

And if size is the priority, then we must be prepared to compromise quality. 

I would continue to recommend 72 ppi for almost all work intended for screen viewing. I would advise against using anything over 100 ppi, it just makes a needlessly large file no matter what nominal screen resolution.

[defaults34jld5w0219]

it would be nice to know which settings use online tasks from the web

[JR Boulay]

Copy-paste these URLs in Google Translate:

Put an end to image resolution

https://abracadabrapdf.net/ressources-et-tutos/creation/en-finir-avec-la-resolution-des-images/

Image compression

https://www.abracadabrapdf.net/ressources-et-tutos/creation/compression-des-images/