Hand colouring refers to the method of manually applying paint to black and white (or sepia) photographs. This was very popular in the mid to late 19th century. Photographers would use water-colours, oils, crayons and other paints or dyes and they would apply them with brushes, fingers or cotton swabs. Depending on how much paint you want to use, the time and focus on it could vary, whether you want to paint small areas or the whole thing. If you decide to paint the whole image, it would take a lot of and effort, particularly if the image has a lot of detail. The process is different to mine, because I did not spend a lot of time on mine, whereas the other photographers have. The difference is their detail and colouring are much more elaborate and my detail and colouring looks rather shabby.
I do like this method, however, because it's a rather creative and imaginative way of making your images look unique. For example, if you have a picture of a person, you could paint their hair green, or their skin purple or their eyes orange, whatever you like. It's your photograph.
Here are a few examples of hand coloured photographs.