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Catégory : PDF

How to Modify a Signed PDF Without Compromising the Signature

January 30, 2023

Once a PDF has been digitally signed, it is usually impossible to edit without compromising the signature. And it’s precisely the purpose of an electronic signature not to be able to tamper with a signed document! However, in some cases, it is possible to amend the file in a way that keeps the original signature […]

PDF Days 2021: That’s a Wrap!

November 17, 2021

Last October, the PDF Association held a series of webinars about various aspects of the PDF format. Our technical presentations covered PDF/A conversion and validation and the growing low code/no code ecosystem for PDF tools. Remote for the second year in a row, the PDF event hosted 24 technical conferences over the month of October. […]

New PDF/A validator

November 9, 2020

Hi Everyone! We’re happy to announce our new PDF/A validator, available with the latest release. Why is it important to validate PDF/A files? Long term archiving is a critical requirement for many industries. Because of the complexity of PDF document format, it is very important to validate if all the PDF/A specification requirements are met.  […]

Using PDF Layers or Optional Content Groups (OCG) in GdPicture.NET

March 23, 2020

Communicating ideas in digital documents can often be made much clearer through the use of layers. Layers have been supported in PDF documents since version 1.5 through optional content groups (OCGs), also known as PDF layers. “Optional” is key here. OCGs allow us to group images or annotations together, then control their visibility based on […]

Methods with Losses: Mixed Raster Content (MRC) Compression

December 20, 2019

Previously in our PDF Optimization In-depth Series: 1. Introduction to the Optimization of Existing PDF files: Methods 2. Lossless Methods: Optimization of Document Content 3. Lossless Methods: Compression of Streams and Fonts 4. Methods with Losses: JPEG 2000 and JBIG2 5. Methods with losses: resizing, color detection, and other techniques MRC compression in PDF documents […]

Methods with losses: resizing, color detection, and other techniques.

December 6, 2019

Previously in the PDf Optimization In-depth Series. 1. Introduction to the Optimization of Existing PDF files: Methods 2. Lossless Methods: Optimization of Document Content 3. Lossless Methods: Compression of Streams and Fonts 4. Methods with Losses: JPEG 2000 and JBIG2 Resizing images Resizing images can provide significant gains in occupancy. For example, decreasing unnecessary high […]

Methods with Losses: JPEG2000 and JBIG2

November 29, 2019

Previously published in the PDf Optimization In-depth Series: 1. Introduction to the Optimization of Existing PDF files: Methods 2. Lossless Methods: Optimization of Document Content 3. Lossless Methods: Compression of Streams and Fonts Sometimes, when acceptable or necessary, it may be interesting to recompress images already included in an existing PDF file to reduce the […]

How to redact sensitive PDF content…efficiently.

November 4, 2019

Don’t get your fingers burned with uncovered sensitive data Have you ever heard of PDF Redaction? If not, well either you don’t have sensitive content to hide, either you are doing it the wrong way. If yes, ask yourself: am I redacting my files properly? In this article, you will learn how to redact PDF […]

Lossless Methods: Compression of Streams and Fonts

October 22, 2019

Here are the links for the two previous articles of the series: 1. Introduction to the Optimization of Existing PDF files: Methods 2. Lossless Methods: Optimization of Document Content A PDF document is composed of various data structures, described as different objects. In the scope of optimization, one is particularly important: the stream object. This […]

Lossless Methods: Optimization of Document Content

October 17, 2019

The first article of our PDF Optimization In-depth Series is available here. The PDF format is interactive.  During the release cycle of a PDF document, different people will use tools such as forms, annotations, attachments, and more. Archived PDF documents generally do not have the same use as those in circulation in a collaborative context. […]