Returns the approx value assigned to this colour description
within its JP2/JPX colour description (
colr) box. Only 4 values are defined for this value by
the JP2/JPX standard, and these are:
-
0 — nothing in particular is known about the
approximation level. This value is to be used with
JP2 files and may also legally be used with JPX files.
-
1 — this colour description is an accurate representation
of the colour space actually used.
-
2 — this colour description is a very high quality
approximation to the actual colour space.
-
3 — this colour description is a reasonable approximation
to the actual colour space.
-
4 — this colour description is a poor approximation
to the actual colour space.
All other values are reserved.