Gimp can't display 12-bit, 1344 by 1024 PGM images.  We in the scientific community love them.  Code below can make one just like my camera takes.
Currently the x and y location of the mouse is displayed at lower, left.  I'd like the pixel value displayed there too.  I dumbed the image down to 8 bits.  Gimp opens it, but the x and y pixel values change by 0.5 pixels, but this should be 1.  The depth is 0 to 1023 but cols are 0 to 1342.5, not 0 to 1343.
Cinepaint displays hi-res PGM but requires manually adjusting brightness since they assumed 16 bit, but I have 12.  I have trouble installing Cinepaint on Ubuntu Linux 8.10.  The Eye On Gnome viewer displays them great, inc thumbnails, but doesn't give pixel values.  What I'm asking for is very few lines of code to do this right.  

Please fix Gimp.  Thanks

#include <iostream> 
#include <fstream> 
#include <algorithm> // copy 
#include <netinet/in.h> // htons 


using namespace std; 


void arrayToPGM(int nCols, int nRows, int maxPixelValue, 
  unsigned short *pixels){ 
  ofstream m_outfile("don.pgm", 
    ios_base::out&ios_base::binary); 


  unsigned short *tmp = new unsigned short[nCols * nRows]; 


  // Convert from "Little Endian" (pc) byte order to 
  // "Big Endian" byte order 
  transform(pixels, pixels + nCols * nRows, 
    tmp, htons); 


  // The magic number MUST be written first. 
  string sMagic = "P5"; 
  m_outfile << sMagic << endl; 


  // Add number of columns, rows, and max pixel value. 
  m_outfile << 
    nCols                     << endl << 
    nRows                     << endl << 
    maxPixelValue             << endl; 


  // Write pixel gray level values into the file. 
  m_outfile.write( (char *) tmp, 
    nCols * nRows * sizeof(unsigned short) ); 
  m_outfile.close(); 


  delete [] tmp; 



} 


int main(){ 
  int nCols = 1344; 
  int nRows = 1024; 
  unsigned short *pixels = new unsigned short[nCols * nRows]; 
  int i, j, k; 
  for(i=0; i<nRows; i++){ 
    for(j = 0; j < nCols; j++){ 
      k = i * nCols + j; 
      if(i > 400 && i < 700 && j > 400 && j < 700) 
        pixels[k] = 4095; 
      else 
        pixels[k] = 0; 
    } 
  } 
  int maxPixelValue = 4095; 
  arrayToPGM(nCols, nRows, maxPixelValue, pixels); 
  delete [] pixels; 
}