{
The following macro illustrates that you can do REAL arithmetic with 
NIH-Image imageMath. Unfortuneately, you cant (yet) save 'real' images but 
you can inspect numbers behind autoscaled pixels via the 'info' window and 
even in the 'histogram' window. 
Note there is a bug in info window display in that if the autoscaled pixel 
has a zero index then the value shows as zero also. However the real value 
lies behind as the imageMath scaling below also illustrates.

In the illustration below, the maximum value generated is ~180*180*180 = 
5,832,000  which scales back correctly to ~89 in 'Product/(256*256)'
You need to scale histogram bin values for yourself if you want to use 
histogram[]. You can do this by using 'measure' to give rMax,rMin.
You may find it convenient to force a scale by seeding your image 
artifically with a know maximum eg using putpixel.
A knowledge of or control of maximum allows you to convert pixel value to 
underlying real value.

Greg Joss
gjoss@rna.bio.mq.edu.au
School of Biological Sciences
Macquarie University
North Ryde, (Sydney,), Australia
}

macro 'Test Real Image Math';
var
 r,t,rs,i,p,o,q:integer;
begin
  setNewSize(256,256);
  setForeGround(255);setBackground(0);
  setPalette('grayscale',6);
  makeNewWindow('Radius Map');
  putPixel(128,128,255);
  invert;
  binary('edm');
  r:=pidNumber;
  duplicate('TestNumbers');
  t:=pidNumber;
  makeRoi(0,0,256,128);
  invert;
  imageMath('mul real',r,r,1,0,'RadiusSquared');
  rs:=pidNumber;
  imageMath('mul real',rs,t,1,0,' RadiusSquared * TestNumbers');
  p:=pidNumber;
  showHistogram;
  setOptions('X-Y Center max user1 user2');
  SetUser1Label('Count');
  SetUser2Label('Level');
  resetCounter;
  measure;
  showResults;
  for i:=0 to 255 do begin
     rUser1[i+1]:=histogram[i];
     rUser2[i+1]:=rMax[1]*i/256;
  end;
  UpdateResults;
  showResults;

  {scaling tests:}
  setCounter(256);
  imageMath('copy real',p,p,1/256,0,'Product/256');
  q:=pidNumber;
  measure;
  imageMath('copy real',q,q,1/256,0,'Product/(256*256)');
  measure;
  showHistogram;
  for i:=0 to 255 do begin
     rX[i+1]:=histogram[i];
     rY[i+1]:=rMax[rCount]*i/256;
  end;
  showResults;
end;