Photoshop Workshop...

Green in RGB Colour:
Change colour profile to CMYK in Image menu:

Same colour in CMYK profile:

Original in RGB:

CMYK Mode:

To view Gamut Warning:

This shows the colours out of range:

Proof Colours to see RGB in CMYK while still in RGB Mode:

File name changes: (.../CMYK)
Ways to apply colour - Swatches:

Colour picker:

Picking Spot Colours from Pantone library:

From Colour Picker, selecting, Colour Libraries:

Creating a Duotone image:
(Original)

Select Image, Mode, Duotone:

Click the black square to pick your Spot Colour:

Apply the Colour to the image:

To adjust the way the colour is applied, click the square next to the black one with the diagonal line through it, here you can adjust the curves:

By changing Monotone in the Type field, to duotone, another colour can be added:

Adjusting the curves, again changes the ways and amounts in which the colour is applied:

And here is the final image:

Creating a Spot Colour image from selection:

Make the selection on the image:

Go to New Spot Channel, in the Channel menu:

Select colour:

Here is the colour applied, normal painting effects can be applied too:

Adjusting the line in the Spot Channel can make the boat look more natural and lose the hard edge:

A large brush with the lowest hardness can take away the hard edge:

And the Spot Channel will now look like this:


And with the Grey channel back in view, the boat looks a lot more natural:

And for the finishing touch, to repaint the oar: