Define legacy NC_proc image scaling

[headmeister]

Summary

• document the exact sign and power-of-two semantics of NC_proc
• give forward-storage and inverse-decoding formulas
• clarify that NC_proc is one exponent with no additive offset
• locate NC_proc/YMIN_p/YMAX_p in procs and distinguish this legacy path from native PV360

Verification

Compared against the PV5.1 and PV6 parameter references and the additional TopSpin processing manuals, including the PV7 manual set. Documentation-only change; no manuals, inventory files, or unrelated ignore changes are included.

[gdevenyi]

Review against the reference material in resources/.

Verified: the NC_proc sign convention (-3 = multiplied by 2 three times; 4 = divided by 2 four times) is in the PV6.0.1 xwinproc processing reference and the PV360 3.7 TopSpin reference; D13 §13.4.11.3 "scaling exponent used for all pixel intensities"; native PV360 PROCNOs have no procs. Correct.

Contradicted by the public data

1. "On disk all three legacy scaling fields are … in procs": YMIN_p/YMAX_p are in nearly every procs, but NC_proc is in a minority (for example 21 of 35 in Zenodo 4048286, 5 of 91 in Zenodo 4048253, 1 of 39 in Zenodo 4522220). The removed narrower sentence was accurate.
2. "the corresponding legacy decode slope is 2**NC_proc": every ParaVision image procs that carries NC_proc has NC_proc=0, while VisuCoreDataSlope is e.g. 182.27 (Zenodo 4048286, expno 10). Non-zero values occur only in TopSpin-processed spectroscopy PROCNOs (1r/1i, no 2dseq). D13 also says the D3 values "may not be set anymore" when Visu parameters exist.

Questions: restrict item 1 to YMIN_p/YMAX_p; scope the formula to TopSpin-processed data and say the image scaling is VisuCoreDataSlope/RECO_map_slope; cite the xwinproc procref and the PV360 3.7 TopSpin reference by name? Then I merge.

[headmeister]

Rebased onto current main and revised the scaling section. The power-of-two formula is now explicitly limited to TopSpin-processed spectral data and cites the TopSpin Processing Reference by name. ParaVision 2dseq scaling is assigned to VisuCoreDataSlope/Offs or RECO_map_slope/offset. YMIN_p/YMAX_p are identified as the consistently present procs fields, while NC_proc is optional; the public image-data observation and D13 warning are included. The available local data confirm NC_proc=0 in all 25 procs files that contain it, alongside independently non-unit Visu slopes, and no procs in native PV360 data.

[headmeister]

Additional mounted-data audit refined one sentence: non-zero NC_proc values occur in spectroscopy PROCNOs containing TopSpin 1r/1i, but those same directories can also contain 2dseq. The text now states explicitly that co-location does not make NC_proc the 2dseq decode exponent.

[gdevenyi]

Revision checked. The power-of-two formula is scoped to TopSpin-processed spectral data and cites procref by name (matches the PV6.0.1 xwinproc text and the PV360 3.7 TopSpin reference); NC_proc is optional and zero beside 2dseq in public PV5.1–PV7 data (reproduces); image scaling is assigned to VisuCoreDataSlope/Offs or RECO_map_*; the D13 warning and the PV360 no-procs fact are in. Merging.