Psimage. Include raster (png) originally with transparency?

I want to place an image rose diagram with no background and transparency fill (-Gred@50) on a map. I create it and save it as PNG, png and eps. I get the result that I want with the eps (right on the figure).

However I expected that it could be done with a raster file. But with the png (center) I get the white background (that I don’t want) and with the PNG (left) the red has NO transparency. Should psimage be capable of do that? Am I doing something wrong? Is it a bug?

Full Script:

gmt begin Rose_Transparency PNG
	gmt rose @fractures_06.txt -: -A10r -S -Gred@50 -R0/1/0/360 -D -Bg
gmt end

gmt begin Rose png,eps
	gmt rose @fractures_06.txt -: -A10r -S -Gred@50 -R0/1/0/360 -D -Bg
gmt end

#	-------------------------------------------------------------------- 
gmt begin Mapa_Rose png
	gmt basemap -Bxfg1 -Byfg1 -R-71/-68/-56/-55 -JM10c -B+g200

	gmt image -Dg-70.5/-55.5+jcM -W3c Rose_Transparency.png
	gmt image -Dg-69.5/-55.5+jcM -W3c Rose.png
	gmt image -Dg-68.5/-55.5+jcM -W3c Rose.eps

gmt end