MeasureImageUniformity.m

function [Result_IU, Parameter] = MeasureImageUniformity( Image, Parameter )
   
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    %Method Description:
    %-------------------

    % Measurement of the Image Uniformity
    %
    % Result_IU contains:
    %
    %   1)      CenterX
    %   2)      CenterY
    %   3)      Radius
    %   4)      Span
    %   5)      Midrange
    %   6)      IntegralUniformity

    [SizeY,SizeX]   = size( Image );
    
    %Determine the position of the phantom inside of the image as well as
    %its radius...
    [CenterX, CenterY, Radius, ~, ~]    = GetPhantomCenter( Image, Parameter, 0, 0, 20 );
    
    %... and store the results in the Result_IU struct
    Result_IU.CenterX   = CenterX;
    Result_IU.CenterY   = CenterY;
    Result_IU.Radius    = Radius;

    %depending on the phantom-radius, calculate the Radius of the ROI,
    %that's being used to measure the image uniformity
    ROIRadius           = Radius * Parameter.IU.RadialSection;
    
    %Draw the ROI to the current plot
    DrawCircle(CenterX, CenterY, ROIRadius, 'red')
    
    %Get a vector containing all image-pixel-values lying in the ROI
    
    %use smoothed image for minimum and maximum determination to be less
    %sensitive to noise
  	GaussFilt           = fspecial('gaussian', round(0.1*[SizeY,SizeX]), 1.0);
 	ImageSmooth         = imfilter(Image,GaussFilt);
    CircularROI         = GetCircularROI( ImageSmooth, CenterX, CenterY, ROIRadius );

    %Get min and max values of all ROI-pixels
    Smax    = max(max(CircularROI));
    Smin    = min(min(CircularROI));
    
    Result_IU.Smax        = Smax;
    Result_IU.Smin        = Smin;
    
    %Calculate Span and Midrange of all ROI-pixels
    Result_IU.Span        = (Smax - Smin) / 2;
    Result_IU.Midrange    = (Smax + Smin) / 2;

    %Determine the integraluniformity where 1 is an optimal value 
    %(perfectly homogeneous ROI-area) and 0 is the worst case
    Result_IU.IntegralUniformity  = 1 - Result_IU.Span/Result_IU.Midrange;
    
    title(['Intergal Uniformity = ',num2str(Result_IU.IntegralUniformity)])

end