Trouble report 376

QTVR quality scale is not comparable to the JPEG quality scale

Versions affected

3.0 - 3.2

Description

With the default image quality setting, the QTVR export format produces images that are unnecessarily large.  QTVR image file size can be reduced without appreciable loss of image quality by reducing the QTVR quality setting.

The QTVR export format produces images that are much larger than the images produced by the JPEG export format when the same quality settings are used on the QTVR and JPEG Settings dialog boxes. For example, setting quality to 75 produces QTVR files that are about twice the size of the corresponding JPEG files.

The quality scales should behave in similar ways for all export formats.  If someone understands how the image quality setting works for one format, that knowledge should (if possible) carry over to other formats. In particular, QTVR images that use JPEG compression should behave similarly to JPEG images.

Workaround

Reduce the QTVR quality image setting to 50 using the QTVR settings dialog box.

Status

Corrected in V3.3.

The QTVR image quality scale has been adjusted to produce image files with size and image quality comparable to the JPEG export format.

Revised: June 23, 2004

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