jp2_dimensions::get_signed

Indicates whether the indicated image component has a signed representation. A false return value means that the quantities are unsigned. Note that all quantities processed by the core Kakadu system are signed quantities. To obtain unsigned values, an offset of half the dynamic range must be added to them. In most cases, this is the appropriate action to take before subjecting the data to any palette mapping, lookup tables, colour conversion, etc. However, if this function returns true, the data should be left in its signed representation and all of the above operations should be performed on the signed quantities. For lookup table operations, this will mean that negative values must be clipped to 0.

As suggested by the foregoing discussion, the JP2 file format was really designed primarily with unsigned representations in mind. Some things make no sense, are clumsy or else are illegal unless the samples have an unsigned representation.

component_idx [int]