void custom_color_map()
{
	// Point to active contour data plot
	GraphLayer gly = Project.ActiveLayer();
	DataPlot dp = gly.DataPlots(-1);
	if( !dp ) return;

	// Get color map into tree object
	Tree tr;
	if( !dp.GetColormap(tr) ) 
		return;
	// Uncomment next line to dump tree in script window 
	// to see what is available
	//out_tree(tr);
	
	// Get current levels
	vector vLevels;
	vLevels = tr.Details.Levels.dVals;
	// Uncomment next two lines to dump current levels
	//for(int i = 0; i < vLevels.GetSize(); i++)
	//	printf("%d %f\n", i, vLevels[i]);
	
	// Now let us change levels, colors etc
	// Following code uses some sample numbers for each
	// Modify code as applicable to your data
	
	// Set new min, max
	double dMin = -5;
	double dMax = 5;
	
	// Change number of levels and values
	// In this example we are setting to a nonlinear scale, 2nd order polynomial
	int nLevels = 32;
	vLevels.SetSize(nLevels);
	for(int i = 0; i < nLevels; i++)
	{
		// Note that level needs to be set as % of (max-min)
		vLevels[i] = 100 * (i^2)/(nLevels^2);
		// Actual value in dialog/GUI will be:
		// uncomment line below to verify
		//printf("%f\n", dMin + vLevels[i]*(dMax-dMin)/100);
	}
	
	// Write new level info to tree
	tr.Min.dVal = dMin;
	tr.Max.dVal = dMax;
	tr.Details.Levels.dVals = vLevels;
	
	// Now let us set colors for each level, using RGB values
	vector<uint>	vColors;
	vColors.SetSize(nLevels);
	// Set colors using some nonlinear function for R, G, B
	for(i = 0; i < nLevels; i++)
	{
		int nRed = 256* i / nLevels;  // linear in R
		int nGreen = 256 * i^2 / nLevels^2; // power of 2 in G
		int nBlue = 128 + 128 * sin(2 * Pi * i / nLevels) ; // sinusoidal in B
		vColors[i] = nRed + 256 * nGreen + 65536 * nBlue + OCOLOR_RGB_BITS;
		// The above sets colors using direct RGB values
		// The offset OCOLOR_RGB_BITS indicates to Origin to interpret as RGB
	}
	
	// Write colors to tree
	tr.Details.Colors.nVals = vColors;
	
	// Can also set above and below color values, such as:
	tr.Details.BelowColor.nVal = 3;	// set to 4th color in Origin color list 
	tr.Details.AboveColor.nVal = 1; // set to 2nd color in Origin color list
	// So can use color list index, or RGB as shown previously
	
	// Set new color map properties using upated tree
	if( !dp.SetColormap(tr) )
		printf("Failed to set color map\n");
}