IMProcessing.metal

    constexpr sampler lutSampler(address::clamp_to_edge, filter::linear, coord::normalized);
    
    kernel void kernel_clutColorMapper(
                                       texture3d<float, access::sample> clut      [[texture(0)]],
                                       device float3                   *reference [[buffer(0)]],
                                       device float3                   *target    [[buffer(1)]],
                                       uint gid [[thread_position_in_grid]]
                                       )
    {
        float3 rgb = reference[gid];
        target[gid] =  clut.sample(lutSampler, rgb).rgb;     
    }