What is color overlay?

Color overlay in this case is adding an extra layer of color on top of the black and white image taken within an editing software, such as Adobe Photoshop, and adding an effect to that picture by messing with opacity etc. For instance adding color to a single specific object in a black and white photo, to make the viewer's attention draw to that singular thing as seen below, it would allow you to draw a viewers attention to a specific object.


From this idea I decided to implement this method into my own photos taken from home, with these being the results from it:

 My aim whilst doing this was to only re-color the parts of the image that I believed stood out from the rest of the picture itself, for example the peg, eye and tubing. From this it would allow the viewers point of interest to drift towards what I want them to mainly focus on, allowing for a greater effect.