[Insight-developers] Question regarding itkColorTable

[James Ross]

Greetings,

I have recently been working with itkColorTable and have a question 
about the UseRandomColors method. When I attempt the following:

typedef itk::ColorTable< float > ColorType;

ColorType::Pointer colorTable = ColorType::New();
colorTable->UseRandomColors( 5000 );

my program crashes.

However, if I alter the body of ::UseRandomColors from:

    r = static_cast<TPixel>(vnl_sample_uniform(NumericTraits<TPixel>
                           ::NonpositiveMin(), 
NumericTraits<TPixel>::max()));
    m_Color[i].SetRed( r );
    g = static_cast<TPixel>(vnl_sample_uniform(NumericTraits<TPixel>
                           ::NonpositiveMin(), 
NumericTraits<TPixel>::max()));
    m_Color[i].SetGreen( g );
    b = static_cast<TPixel>(vnl_sample_uniform(NumericTraits<TPixel>
                           ::NonpositiveMin(), 
NumericTraits<TPixel>::max()));
    m_Color[i].SetBlue( b );

to:

    r = static_cast<TPixel>( vnl_sample_uniform( 0.0, 1.0 ) );
    m_Color[i].SetRed( r );
    g = static_cast<TPixel>( vnl_sample_uniform( 0.0, 1.0 ) );
    m_Color[i].SetGreen( g );
    b = static_cast<TPixel>( vnl_sample_uniform( 0.0, 1.0 ) );
    m_Color[i].SetBlue( b );

my program runs, and I get expected behavior. Why are the color 
components randomly chosen in the interval from non-positive min to max 
in the original? Isn't the floating point color component convention 
associated with the interval [0.0, 1.0]?  If the original is a logical 
bug, I'd be happy to fix and commit. If I'm doing something incorrectly, 
please let me know.

Many thanks,

-James