nf: some small updates to transmit scl_slope and scl_inter, also allo…

…w for int8 as datatype (freesurfer#840)

matlab/MRIwrite.m

@@ -79,6 +79,8 @@
 if(~isfield(mri,'volres'))
     mri.volres = sqrt(sum(mri.vox2ras0(1:3,1:3).^2));
 end
+if(~isfield(mri,'scl_slope')) mri.scl_slope = 0; end
+if(~isfield(mri,'scl_inter')) mri.scl_inter = 0; end
 
 [fspec fstem fmt] = MRIfspec(fstring,0); % 0 = turn off checkdisk
 if(isempty(fspec))
@@ -137,6 +139,7 @@
    case 'int',    hdr.datatype = 8;   hdr.bitpix = 8*4;
    case 'float',  hdr.datatype = 16;  hdr.bitpix = 8*4;
    case 'double', hdr.datatype = 64;  hdr.bitpix = 8*8;
+   case 'char',   hdr.datatype = 256; hdr.bitpix = 8*1;
    case 'ushort', hdr.datatype = 512; hdr.bitpix = 8*2;
    case 'uint',   hdr.datatype = 768; hdr.bitpix = 8*4;
    otherwise,
@@ -149,8 +152,8 @@
   hdr.pixdim          = [0 mri.volres([2 1 3]) mri.tr]; % physical units
   %hdr.pixdim          = [0 mri.volres mri.tr]; % physical units
   hdr.vox_offset      = 348; % will be set again
-  hdr.scl_slope       = 0;
-  hdr.scl_inter       = 0;
+  hdr.scl_slope       = mri.scl_slope;
+  hdr.scl_inter       = mri.scl_inter;
 
   hdr.slice_end       = 0;
 

matlab/load_nifti.m

@@ -132,6 +132,7 @@
  case   8, dtype = 'int' ;
  case  16, dtype = 'float' ;
  case  64, dtype = 'double' ;
+ case 256, dtype = 'int8' ;
  case 512, dtype = 'ushort' ;
  case 768, dtype = 'uint' ;
  otherwise

matlab/save_nifti.m

@@ -158,6 +158,7 @@
  case   8, nitemswritten = fwrite(fp,hdr.vol,'int');
  case  16, nitemswritten = fwrite(fp,hdr.vol,'float');
  case  64, nitemswritten = fwrite(fp,hdr.vol,'double');
+ case 256, nitemswritten = fwrite(fp,hdr.vol,'int8');
  case 512, nitemswritten = fwrite(fp,hdr.vol,'ushort');
  case 768, nitemswritten = fwrite(fp,hdr.vol,'uint');
  otherwise,