When converting a PSD file with a transparent background using GraphicsMagick, my PNG image is more "dull/lighter" than the source image. 

I've used the following

gm mogrify -level (with countless options)  

gm mogrify -modulate (with countless options)  

gm mogrify -gamma (with countless options)  

gm mogrify -normalize   

gm mogrify -colorspace srgb  

What other options do I have in order to get the source PSD and the rendered PNG to match closely? The color is very important as they are related to product that consumers can purchase. If the color doesn't match, they may order it and not like what they receive.