Here are a couple of images that I am working on for my wedding album, and after seeing that there was a request for a how to from the lady in red thread. I thought I'd get off my arse and type it up for all of you.
tutorial: how to colourise only sections of an image.
Open the image in your editor of choice. It must support the use of layers (ie photoshop or the Gimp).
If you are using images import them in and adjust them as you normally would.
Once in PS or the gimp duplicate the background layer, and give it a fairly meaningful name. (this is not really that important, but it may help you if you go back through your old images and try and work out what you have done, I usually use "colour" for my naming of the layer)
turn visibility off the background layer. then select the layer that you want to modify.
now for the hardest part. You need to select just the part of the image that you want coloured. This will be time consuming, and will take a couple of goes to get it right (esp when using a touchpad instead of a mouse.
a)the eraser tool, Using varying size erasers and levels of zoom erase out the parts original image that you dont want in colour. This I have found to be the easiest especially if you reduce the hardness of the edges. It will make the transition fairly seemless.
b)The lasso tool, same sort of principle as the eraser tool I have found it easier to select chunks of the non-coloured image and delete them, rather than the coloured image. This does depend on complexity
c)The magic wand tool, I have had mixed results with the magic wand tool. It hasnt been overly successful, and I have had too much of a chance to play with it further.
Once you are happy with the image that you have cropped, you now need to make the background visible, and hide your "colour" layer
The method that I prefer to use for making the image B&W is to add a New Adjustment Layer ==> Hue and saturation
note: make sure that it is only on the background layer.
reduce the saturation on Master, how far to reduce the saturation is really up to personal choice and the image. I have done both full B&W and still having a little colour
Make your colour visible.
and if you are going to be using the image in something like a collage make sure you flatten the layers.
Couple of Things to try. Increase the colour saturation on the colour layer. it gives it a more surreal effect.
And if you get through all that and give it a try, post your results here