quantize pair fix

src/MATLAB/+NCD/ncd_ssf_volume.m

-% i1 and i2 are signal kymos (x,y,t,c)outdir
-% we want images {t}(x,y,c)
-% package to cell array by t and then pass to in memory FLI%F compressor
+% i1 and i2 are each 3.3D images, e.g. (x,y,z) or (x,y,t), etc.
+% package to cell array by z or t and then pass to in memory FLIF compressor
+% if images are not uint8, they will be quantized to uint8 (FLIF does not
+% like floats)
 function ncd = ncd_ssf_volume(i1,i2)
 
 [i1,i2] = NCD.quantizePair(i1,i2);

src/MATLAB/+NCD/quantizePair.m

 % clip image pairs and quantize, per channel (x,y,z,c)
+% best practice -- quantize all embedded data jointly
+% if images already quantized (uint8), just return them
+% otherwise quantize image pair
 function [i1q,i2q] = quantizePair(i1,i2,clipLimits)
+
 if isa(i1,'uint8') && isa(i2,'uint8')
+    i1q = i1;
+    i2q = i2;
     return
 end
+
 if ~exist('clipLimits','var')
     clipLimits = [0,100];
 end
+
 if size(i1,4) ~= size(i2,4)
     fprintf(2,'WARNING : quantizePair : input images of different color channel dimension\n');
 end