1. A method, comprising: receiving an input visual dynamic range (VDR) image and an input base layer (BL) image associated with the input VDR image; generating a coding syntax for encoding-related operations comprising a plurality of syntax elements, wherein the coding syntax specifies a set of operations performed by an upstream encoder to generate BL data and enhancement layer (EL) data; converting the input BL image and the input VDR image into the BL data and the EL data in accordance with the coding syntax by performing the set of operations as specified in the coding syntax; wherein the EL data comprises residual values between the input VDR image and a predicted VDR image generated based on the BL data; wherein the plurality of syntax elements specifies one or more of: chroma resampling operations, inverse mapping operations, non-overlapped-region-based prediction operations, overlapped-region-based prediction operations, residue non-linear quantization and dequantization operations, residual chroma resampling operations, residual spatial upsampling operations, data processing operations including interpolations, which are performed to generate the BL and EL data; wherein the plurality of syntax elements comprises syntax elements for inverse mapping operations that include a plurality of pivot indices dividing an output dynamic range into different dynamic range segments of respectively different brightness levels; encoding the plurality of syntax elements in the coding syntax into reference processing unit (RPU) data to enable a downstream decoder to use the same coding syntax for decoding-related operations; wherein the RPU data comprises a current RPU data unit; and outputting the BL data, the EL data and the RPU data in BL, EL and RPU signals; wherein the current RPU data unit comprises a flag indicative of whether frame level syntax elements of previously sent RPU data should be reused.