[PDFBOX-4655] ImageIOUtil.WriteImage creates huge PNG images when used with default quality on jdk11

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0.17
• Fix Version/s: 2.0.18, 3.0.0 PDFBox
• Component/s: Utilities
• Labels: imageio jdk11 jdk12 jdk13 png
• External issue URL: https://mail-archives.apache.org/mod_mbox/pdfbox-dev/201909.mbox/%3CCAC1dCwW7b8Jr8OYHLK9DGiJ0oYm6-BaeoiZw8C8NoLFOJf7CVQ%40mail.gmail.com%3E
• Assignee: Tilman Hausherr
• Reporter: Tilman Hausherr
• Created: 21/Sep/19 11:08
• Updated: 23/Dec/19 22:16
• Resolved: 21/Sep/19 13:18

Description

[e-mail] pointed us to a build failure in Tika on jdk11. The cause may be different .PNG files - I noticed that PNG files saved with ImageIOUtil.write() are huge when done with default quality on jdk12 / 13, which is 1. In the past (jdk8 and before) that parameter had no effect for PNG files but apparently no more.

Thus I'll set compressionQuality to 0 to ensure maximal compression. PNG is a lossless format so there is no risk.

Todo:

• use flexible default value
• mention in Javadoc
• change command line tool PDFToImage
• change one test