Efficient xor cursor ... in color?

General Usage
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2

My mistake. Julia makes the UInt8 data available in color images. I was just indexing it incorrectly. The following color plot with a golden color xor cursor was generated with the following code:

trash4
trash41920×1079 108 KB 

	# load map and arrow
	img_map = load("bok.png"); # Array{RGBA{N0f8},2}
	img_map_num = reinterpret(UInt8, img_map);
	img_map_chan = reshape(img_map_num, (4,:))
	img_arrow = load("iconArrow301.png") # # Array{RGBA{N0f8},2}
	img_arrow_num = reinterpret(UInt8, img_arrow)
	img_arrow_chan = reshape(img_arrow_num, (4,:))
	nMap = size(img_map,1)
	nArrow = size(img_arrow,1)
	
	# draw arrow in map
	x0 = 949
	y0 = 1845
	for iColorChan = 1:3
		img_map_color = reshape(img_map_chan[iColorChan,:], (nMap,:))
		img_arrow_color = reshape(img_arrow_chan[iColorChan,:], (nArrow,:))
		img_map_color[y0:y0+nArrow-1,x0:x0+nArrow-1] .= xor.(
			img_map_color[y0:y0+nArrow-1,x0:x0+nArrow-1], 
			img_arrow_color)
		img_map_chan[iColorChan,:] = img_map_color[:]'
	end
	img_map_num = reshape(img_map_chan, (nMap*4,:))
	save("trash4.png", img_map)