function toImageData (colors) {
	return colors.map((color) => color.map((v) => v*255).concat(255))
	.reduce((prev, curr) => prev.concat(curr));
}
function toImageData (colors) {
	return colors.map((color) => color.map((v) => v*255).concat(255))
	.reduce((prev, curr) => prev.concat(curr));
}
function toImageData ( colors ) { return colors . map ( ( color ) => color . map ( ( v ) => v * 255 ) . concat ( 255 ) ) . reduce ( ( prev , curr ) => prev . concat ( curr ) ) ; }
return imagedata from colormap
return imagedata from colormap