The Persistence of Vision Raytracer (POV-Ray).

This is the legacy Bug Tracking System for the POV-Ray project. Bugs listed here are being migrated to our github issue tracker. Please refer to that for new reports or updates to existing ones on this system.


FS#103 - JPEG output does not conform to baseline JFIF standard

Attached to Project: POV-Ray
Opened by Christoph Lipka (clipka) - Tuesday, 27 April 2010, 16:00 GMT
Last edited by Christoph Lipka (clipka) - Sunday, 29 August 2010, 20:09 GMT
Task Type Definite Bug
Category Frontend → Image format
Status Closed
Assigned To Christoph Lipka (clipka)
Operating System All
Severity Low
Priority Normal
Reported Version 3.70 beta 37
Due in Version 3.70 beta 38
Due Date Undecided
Percent Complete 100%
Votes 0
Private No


POV-Ray 3.7-generated JPEG image output files do not conform to the JFIF standard. Most importantly, the files written do not use the standard YCbCr color model (they seem to use plain RGB instead), nor do they have a proper JFIF tag.

As a consequence, some software may be unable to read the generated JPEG files properly. In addition, it seems that POV-Ray mixes up the Red and Blue channels.

This task depends upon

Closed by  Christoph Lipka (clipka)
Sunday, 29 August 2010, 20:09 GMT
Reason for closing:  Fixed
Comment by Christoph Lipka (clipka) - Tuesday, 27 April 2010, 16:17 GMT
  • Field changed: Status (Investigating → Requires testing)
  • Field changed: Due in Version (Undecided → 3.70 beta 38)
  • Field changed: Percent Complete (0% → 100%)

fix submitted as change #4956

Comment by Thorsten Fröhlich (thorsten) - Wednesday, 28 April 2010, 17:12 GMT

This color swap is a bug indeed, but the RGB output is not. IIRC not having a plain JFIF tag is a requirement for some software to grasp that the encoded image is RGB rather than YCC. Using RGB has several benefits over a YCC for ray-traced images that have sharply defined object borders, a traditional weakness. While more pronounced with reduced chroma resolution of the default 4:2:0 sampling used by most JPEG software, even with 4:4:4 sampling the artifacts remain.

Comment by Grimbert Jérôme (Le_Forgeron) - Monday, 09 August 2010, 12:10 GMT

Jpeg output with beta38 (from source) is ok regarding the displayed colours.
No problem to display the native jpeg with imagemagick.