png format - How to export a Graphics to PNG with BitDepth greater than 8?

According to the PNG ref page, it is possible to generate PNG with 8 or 16 BitDepth. I cannot find a way to impose 16 for a graphics generated by Plot. Here is the example:

gr = Plot[Cos[x], {x, -4, 4}, Filling -> Bottom];
png=Export["test.png", gr, "BitDepth" -> 16];
Import[png, "BitDepth"]

(* out *) 
8

Thanks

Answer

I guess the rasterization into a 16 bit image is not done even though you specified the option. Does it work for you, if you use this:

gr = Plot[Cos[x], {x, -4, 4}, Filling -> Bottom];
png = Export["test.png", Image[gr, "Bit16"]];
Import[png, "BitDepth"]

Comments

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