As shown on the main page, techniques such as double printing can be done in the darkroom. There are many other effects possible, some of which involve different paper or sheet film. In the example below, an image of blue agave is printed on three different media. First is cooltone variable contrast paper with a filter, second, on warmtone paper with no filter, third, on lithography sheet film, and finally, a contact print of the lith positive with the continuous tone image from the negative illuminating the warmtone paper. The effect of this is to print a positive and negative image simultaneously, giving contrast reversal in some regions and enhancing edges.
They are all scanned in color, with a greyscale (in Photoshop) image shown also for comparison.
I will show similar examples of an old ornamental well house.
The earliest technique for producing color photographs was to take a black and white print and hand-color it. My first attempt at such is shown below - I hope to improve my technique!
In the main section of this website, dealing with microscopy and macro photography, there are sections regarding post-processing of images. Much of that is relevant here, of course, especially the processing page, so feel free to look through that section as well.
In the computer, artistic effects such as the following are fairly easy. I started with a silhouette image of a female black widow spider on her web, and another with a flash. Tweaking the flash photo in several ways and combining it with the silhouette made the final image, which is a bit abstract, but appears as though there is a shadow.
Another type of manipulation in Photoshop is to colorize black and white photos. In this example, after changing from greyscale to color, I first selected the lettering and put a gradient of color and then applied a "plastic wrap" filter. Then I did a craquelere filter over the rest of it, gave the edge cracks some color and then painted around that. Finally, I gave a slight yellow tint via a photo filter to the whole thing.
Stacking is a technique that allows multiple images to be blended by making the top ones semi-transparent. Here I have combined the normal warmtone image of the wellhouse above with two of the lith film manipulated versions. The second image has clearly been colorized in Photoshop, as well.
It is also easy to "clone" an image or part of one, as done below. The original image is black and white from The University of Arizona Art Museum. Here, after rotation, I made a second copy, reversed it horizontally, selected (lasso) the right hand, inverted the color map, applied a photo filter, then applied a slight change in tint to the whole image. The effect I was going for was black and white (skin tones) coming together in peace.