Conversion from BGR8888 to XR_BIAS

This section applies only to Windows 7 and later operating systems.

The conversion from BGR8888-type formats (for example, DXGI_FORMAT_B8G8R8A8_UNORM) to XR_BIAS is lossless.

The scale factor of 510 is explicitly chosen to provide a cleanly invertible conversion between a BGR8888-type format and XR_BIAS without causing the nonlinear jump near 0.5 that would be implied by a scale factor of 511.