DS9 Region File Format Limitations¶

Region Shapes¶

The following DS9 regions shapes do not have corresponding Region classes and therefore are not supported:

panda, epanda, and bpanda

vector

ruler

compass

projection

Region objects represent abstract shapes that are not tied to any particular image or WCS transformation. Therefore, the following DS9 coordinate frames are not supported:
- physical
- detector
- linear
- amplifier
- tile
- wcs and wcs0
- wcs[a-z]
If you have a DS9 region file that uses one of these coordinate frames, you can load it into DS9 with its corresponding image/WCS and then save the region with a coordinate frame supported by this package (e.g., image, ICRS, FK5, etc.).
A coordinate frame must be specified in the DS9 region file. This package does not assume a default coordinate frame.
DS9 regions with mixed coordinate systems within a region specifier are not supported. For example, a region file with an image coordinate frame must not have angular sizes, e.g., image; circle(650, 932, 3') is not supported.

Reading and then writing a DS9 region file will not produce an identical file to the original, but the encoded regions are identical. Therefore, it will produce identical Region objects when read back in again. In other words, read/write/read (or parse/serialize/parse) will exactly roundtrip Region objects.
DS9 composite regions are parsed into separate, independent Region objects.

The point symbol size must be a integer (matplotlib limitation).
Point symbols may not have dashed lines (matplotlib limitation).
Point symbols can be plotted with filled colors, which DS9 does not support. Because of this, DS9 serializations will ignore the fill=1 metadata.
Annulus regions can be plotted with filled colors, which DS9 does not support. Because of this, DS9 serializations will ignore the fill=1 metadata for annulus regions (annulus, ellipse, box).
Text labels are plotted only for TextPixelRegion objects. For other region objects, the text labels are stored in the region metadata.