Your turn
Now it's your turn to pick an image and to colorize it. Take as an example the following image:

It is a photograph from the Digital Collections of The New York Public Library. The image shows Lev Trotsky, Vladimir Lenin and Lev Kamenev at the 2nd Congress of the Bolshevik Party in 1919.
Retouched Photograph
First of all, the photograph was healed with the Healing brush. As you can see in the original, Kamenev's shoulder has a scratch and the upper left corner of the image is slightly damaged. In order to increase contrast and to adjust lightness, I used “Curves” functionality in Photoshop. If you'd like to use it, you should follow this path: Image<Adjustments<Curves. In order to pick the points of contrast, I used Eyedropper tool.
Vignette
I created a new Layer above the main image and then filled it with color. Afterwards, I selected the vignette on this layer with Elliptical Marque tool and used the Move tool to adjust the borders of the vignette.
In this case, I created a Layer Mask and then with the Gradient tool, I got this gradual transition between colors.
Colored Image
This is an example of how you should not color an image. Although, if you like Andy Warhol, this is the way you have to go. To get this colorization, you just need to use the Paint tool and pick a color for each element of the picture.
The following is an example of an appropriate colorization. To achieve this effect, I used the Brush tool and set a Color Mode.
