Downsample PDF with better quality.

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pargorner
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Posts: 19
Joined: Mon Jan 10, 2011 4:19 pm

Downsample PDF with better quality.

Post by pargorner » Tue Nov 29, 2016 2:05 pm

Hi

I know there is a lot of topics about creating PDF´s with a certain resolution.

And maybe I´m just doing it wrong.
But I need to downsample existing print ready PDF´s to both 144 and 72 dpi, and I need to do this with a better quality than I can get from Pitstop Server.



Any suggestions?


Best regards

Pär

freddyp
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Joined: Thu Feb 09, 2012 3:53 pm

Re: Downsample PDF with better quality.

Post by freddyp » Thu Dec 01, 2016 10:02 am

PitStop Server offers 5 different algorithms for resampling images. The bicubic B-spline resampling is generally considered to be the best, but you may beg to differ. It is also worth checking which one you are using currently.

And just to make sure: do not resample to 72 from the 144 version! Always resample from the original.

pargorner
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Posts: 19
Joined: Mon Jan 10, 2011 4:19 pm

Re: Downsample PDF with better quality.

Post by pargorner » Fri Dec 02, 2016 8:13 am

Hi Freddy

I have tried the different algorithms and but no one produces a satisfying result.
All of the downsampling is from pdf´s with 400 dpi images.

Today I am using PDF Enhancer, but having some issues with processing some files so I want to look at other options.

Attaching two jpegs to illustrate the differens between PDF Enhancer and Pitstop Server.
Take a look at the harder lines/details that Pitstop produces. They are details at 400%.

Cheers

Pär
Attachments
PDF Enhancer.jpg
PDF Enhancer.jpg (213.34 KiB) Viewed 6342 times
Pitstop Server.jpg
Pitstop Server.jpg (252.64 KiB) Viewed 6342 times

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Terkelsen
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Re: Downsample PDF with better quality.

Post by Terkelsen » Fri Dec 02, 2016 8:34 am

Sorry to say Pär, but IMHO the sample from Pitstop looks better than that from PDF Enhancer :roll: . You are right, that lines are harder but to me it just looks as if the image i sharper. The blurry look at the sample from PDF Enhancer seems to derive from a much lower JPEG compression. If you really want that blurry look, try to set the JPEG-compression in Pitstop to Low og Min.

pargorner
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Posts: 19
Joined: Mon Jan 10, 2011 4:19 pm

Re: Downsample PDF with better quality.

Post by pargorner » Fri Dec 02, 2016 1:27 pm

Thank you for your reply, but I have to disagree.

And it is not the compression artifacts I´m not worried about. That can, as you say, be adjusted in the settings.

I have attached the images again in a smaller size, and I think it is easier to detect the issue.
Especially noticeable if you look at the chrome surrounding the side windows.

/Pär
Attachments
PDF Enhancer 2.jpg
PDF Enhancer 2.jpg (245.66 KiB) Viewed 6337 times
Pitstop Server 2.jpg
Pitstop Server 2.jpg (239.46 KiB) Viewed 6337 times

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