<p>In <a href="https://github.com/mlpack/mlpack/pull/683#discussion_r66470019">src/mlpack/methods/edge_boxes/feature_extraction_impl.hpp</a>:</p>
<pre style='color:#555'>&gt; +    table(i) = i / 1024.0;
&gt; +    
&gt; +    if (table(i) &gt; y0)
&gt; +      table(i) = 116 * pow(table(i), 1.0/3.0) - 16.0;
&gt; +    else
&gt; +      table(i) = table(i) * a;
&gt; +
&gt; +    table(i) = table(i) * maxi;
&gt; +  }
&gt; +
&gt; +  MatType rgb2xyz(3,3);
&gt; +  rgb2xyz(0,0) = 0.430574; rgb2xyz(0,1) = 0.430574; rgb2xyz(0,2) = 0.430574;
&gt; +  rgb2xyz(1,0) = 0.430574; rgb2xyz(1,1) = 0.430574; rgb2xyz(1,2) = 0.430574;
&gt; +  rgb2xyz(2,0) = 0.430574; rgb2xyz(2,1) = 0.430574; rgb2xyz(2,2) = 0.430574;
&gt; +
&gt; +  //see how to calculate this efficiently. numpy.dot does this.
</pre>
<p>Here is the implementation of <a href="http://www.mathworks.com/matlabcentral/fileexchange/36433-stereo-testbed-v0-1/content/ALGORITHMS/3DStereoDisp/msseg/RGB2Luv.m">matlab</a>, if we want speed, I think we better make use of the operations provided by armadillo, because armadillo do a lot of heavy optimization on matrix operations(matlab codes show us how to vectorize it)</p>

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