RadialGradientImage
RadialGradientImage[gcol] returns an image with values radially changing from center to corners based on gradient color gcol.
RadialGradientImage[{pos1,pos2}->gcol] returns an image where the gradient starts at pos1 and ends at pos2.
RadialGradientImage[…,size] returns a radial gradient image of the specified size.
RadialGradientImage[…,size,"type"] gives an image converted to the specified type.
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