I've always had trouble getting a Grayscale image to print as grayscale!
Sometimes on an RGB (non-postscript) printer it prints 'brownish'. Because the print machine is beside me, I can tinker and print till I get it right.
Sometimes when I send a Grayscale image off as CMYK or as Grayscale (whichever they ask for) to a commercial printer, the print is much darker than I had intended. And sometimes it's fine!
Is there a formula for getting it right every time?
A grayscale image converted to the grayscale color profile and exported as TIF is best for press. Of course the print shop could be awful.
If printing to a non-postscript printer you yet what've call here in the States Pot Luck. Some of those devices and the paper used are just awful.
If just running some on your desktop printer try desaturating a color image and sending as RGB. In my opinion that's you best chance with non-posrscript devices.
I see CorelDraw can convert to the 'default' Grayscale Dot Gain 15% on import.
Then it's just a matter of exporting to CMYK (with default ticked 'Map gray to CMYK black'). Right, so that keeps it all using black ink only.
Should a person check with the commercial printer what Dot Gain they use?
Re Desktop Printer, I'll try desaturating and sending to RGB.