Decode HDR compression in Shader sampler


I have made some FX based on mesh vertex coords. Vertex coordinates packed to RGB linear color (r = x, g = y, b = z) and drawed colored line 1px dimension to canvas to via drawLine. Then i export render target canvas with drawed cooords to file (format: floatRGBA, compression: HDR compression). How i can decode texture floatRGBA with HDR compression in the Material or HLSL shader?

I try to decode based on code inside of Color.cpp. But without luck =(