[PDFBOX-4267] Incorrect rendering when /Matte entry

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0.11, 3.0.0 PDFBox
• Fix Version/s: 2.0.12, 3.0.0 PDFBox
• Component/s: Rendering
• Assignee: Tilman Hausherr
• Reporter: Tilman Hausherr
• Created: 17/Jul/18 17:04
• Updated: 05/Oct/18 04:53
• Resolved: 18/Aug/18 16:51

Description

The image softmask in the attached file has a /Matte 0 0 0 entry. PDFBox displays the PDF differently than Adobe Reader, the reflection shown by PDFBox is barely visible. When the /Matte entry is deleted, then it is barely visible in Adobe Reader too. So the /Matte entry does make some difference, although I don't understand how.

In the PDF specification, the formula shown is c' = m + α x (c - m). So 0 should have no effect?!

I looked at the code of PDF.js, they have a special handling when alpha is 0, don't know why.

Issue Links

• links to: PDF.js commit that takes SMask's preblending in account
• links to: Transparency in PDF files in Firefox 22
• links to: Transparency with pre-multiplied alpha does not match Adobe Acrobat