Image printing in Black ink. Grayscale or RGB colorspace?

[pcmodem]

I have a client who sent in an RGB image which has the color removed; ie one spot on the photograph has the same amount of RGB.

The client wants this to print just using Black ink.

Is this how you would provide the file?

Or would you convert it to grayscale before sending to the printer?

 

[Lukas Engqvist]

Normally I would convert to grayscale, this can easily be done in Acrobat Pro though using convert colour.
Depending on your process you will need to set the dot gain or why not convert to output intent preserving black and select a monochrome profile.

If you have an image and want to change to greyscale then Photoshop will say to use the black and white filter, for more control. If you want you can embed the original by converting to smart object before converting to gray (at the expense of larger file size)

 

[pcmodem]

I thought, converting to grayscale would be the best choice. After all, what if the image is suppose to print in Black ink but there are other images on the page which are to print in CMYK.

 

[Lukas Engqvist]

if you look at an indigo then you may have 4x cost and time to print if you send it as RGB gray. (If you want it rich gray I have best results by converting to gray in PS and colouring with a 20 15 15 100 swatch in InDesign, smoothes out the screen by adding c m y in the white space )