Greyscaler

One of the very few things that PSP cannot do directly is convert a single layer to greyscale without affecting the other layers as well. The only option available is (from the menus) Colors->Greyscale, and this converts the whole image - in other words, all layers. The xero : greyscale filter addresses this shortcoming, and adds some useful extras as well.

	This is the picture we're going to work with. Now, greyscale conversion isn't the most exciting effect in the world, but with a little imagination it can become a very useful creative tool. Straightforward greyscaling is a trivial process that can be done without any user-controls at all, but the xero : greyscaler offers three settings...
The 'Levels' slider controls the number of greyscale levels to which the picture will be quantised; by default, you'll get the full range. Remember that you won't see any real difference in the preview window unless the number of levels is set toward the low end of the scale. In addition to the number of levels, you can also alter the brightness and contrast. All three of these functions can be performed in PSP, of course, but it can be convenient to have them available in the filter. In this case, I've set the number of levels right down to 6, and boosted both brightness and contrast by about 50. Now, lets see what we get...
	Already we have quite an appealing picture, to my eyes at least. However, what I didn't mention earlier is the fact that before greyscaling the picture, I duplicated the original layer. We now have the original coloured picture with the quantised, greyscaled copy directly above it. Let's play around with the layer merge modes; double-click the upper layer's entry in the layer palette to open its properties dialog.
First, set the merge mode to 'Luminance' and the layer opacity to about 60%; we get something that looks a little like an ink drawing.
Alternatively, set the merge mode to 'Screen' and opacity to around 70% to get something similar, but lighter in tone.
Or with the merge mode set to 'Overlay' and opacity, again, at around 70% we get something much more solid-looking.
Set the upper layer's opacity back to 100%, and use PSP's wonderful 'Edge-preserving smooth' filter on it to get a sort of 'gouache' look...
Finally, set the upper layer's opacity down to around the 55% mark to let some of the original colour through, and we have a nice 'watercolour' look!