PDFsharp & MigraDoc Foundation

PDFsharp - A .NET library for processing PDF & MigraDoc Foundation - Creating documents on the fly
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 Post subject: Optimize PDF file size
PostPosted: Tue Aug 07, 2018 11:14 am 
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Joined: Mon Nov 06, 2017 3:53 pm
Posts: 18
Hello,

at first I want to thank you for the great library you provide.

Now I'm a bit in a tricky situation and I hope you can help.

I'm creating a PDF containing three tables. One in the header, one in the body and one in the footer.
This PDF can be rather long (70 DIN-A4 pages each page has about 40 rows in their table). Each page as a bookmark, so the user can jump to them easily. The fonts are not embedded in the pdf, I use the fonts coming from windows. The size of the file is about 10MB. Which is way to big.

I guess the cause of this is that each line of the main body table contains two pictures which I create in runtime. These are only Icons (36*36px) and pictures which have a maximum size of 200x50px. Resolution is 72 in horizontal and vertical.
I put the images in the chart by converting them into binary and add them to to cell.

Code:
string strRedRectangle = "base64:" + Convert.ToBase64String(byRedRectangle);
cell.AddImage(strRedRectangle).Width = "5pt";


Each picture is about 2kb.

How can optimize the size of the pdf file? Because I've read that the 'released' dll creates much smaller files than the 'debug' version of pdfsharp, I'm using the release version of pdfsharp.

I cannot make the icons smaller :(

Has someone a suggestion?
A third party console application which can be called after creating the pdf to make it smaller is also welcome.

Thank you!


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PostPosted: Tue Aug 07, 2018 11:39 am 
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Joined: Mon Oct 16, 2006 8:16 am
Posts: 2980
Location: Cologne, Germany
First find out what contributes to the size of the PDF file.
With PDFsharp there will be embedded fonts in the PDF file. Using different fonts (or maybe a different build of PDFsharp) could reduce the file size.
Check if there are duplicated copies of your images in the PDF - anything else is just speculation.

Have you seen this post:
viewtopic.php?f=8&t=3748

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Thomas Hoevel
PDFsharp Team


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PostPosted: Tue Aug 07, 2018 12:10 pm 
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Joined: Mon Nov 06, 2017 3:53 pm
Posts: 18
Thank you for your answer.

Yes I've seen the linked post and I'm running it in BestCompression and I'm using the release build of pdfsharp.

For finding the source of the file size I removed the images and the size dropped drastically to under one megabyte. So the images are causing this.

As said I create the bitmaps during runtime and add them when created to the cell in the table. I cannot get the size down of the images (36*36) and 200*50px because they will get unreadable.

Any idea?


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PostPosted: Tue Aug 07, 2018 12:37 pm 
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Joined: Mon Oct 16, 2006 8:16 am
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Location: Cologne, Germany
Save the images to files - just one file per unique image.
Then reference the files in calls to "AddImage()". Only a single copy of each file should now be added to the final PDF.

It could be that the current implementation of the "BASE64" magic prevents this file size optimization and includes multiple copies of identical images.

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Thomas Hoevel
PDFsharp Team


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PostPosted: Wed Aug 08, 2018 12:51 pm 
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Joined: Mon Nov 06, 2017 3:53 pm
Posts: 18
To give you a quick feedback.

It really seems that the "BASE64" magic prevents the file size optimization.

To solve this I came up with the following.

1) Create an empty list containing images and a name.
2) Check if an entry with an unique name exists.
2.1) If the name was not found. An image will be created, added to the list with its name and saved to a temporary directory.
2.2) If the name was found don't create a bitmap
3) Clone found/created bitmap and add it to the cell.

Now I'm down to about 1.5MB (former 10MB!) which is OK.

Sadly, I cannot do this with all bitmaps created during runtime because some do differ in details to each other and it would not make a difference if I save them and put insert them into the cell, or directly inserting them into the cell via "BASE64".

Thank you again!


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