Gets the colour space of the samples, as resolved before default colour spaces apply.
public PdfColorSpace ColorSpace { get; }
ISO 32000-2 §8.9.5.1, Table 87 (ColorSpace); for a JPEG 2000 image without one, the codestream's (§7.4.9). Never a Pattern space; image masks (§8.9.6.2) are not interned here.