Now that we are deep into implementing the Blending Softcopy
Presentation State, we have identified an issue with its IOD.

In the Grayscale and Pseudo-Color Softcopy Presentation State IODs,
the Modality LUT Module and the VOI LUT Module are conditionally
included, depending upon the applicability of the LUT to the
presentation.

However, in the Blending Softcopy Presentation State the Modality LUT
becomes mandatory, since there is no conditionality in the invocation
of the Modality LUT Macro. Similarly, there is no conditionality on
the VOI LUT.

Why is BSPS not constructed equivalently to GSPS for the BSPS
underlying image, and to PCSPS for the BSPS superimposed image?
Shouldn't the same conditionality apply?

Of course we can create a "unity" LUT (rescale slope/intercept, or
window width/center), but then the encoding in BSPS by requiring this
is arbitraily different than the presentation states in the unblended
cases.

- Harry