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There is a technique in photography, called Invisible Black Background. You can find details about it in this blog post Dramatic Portraits with the Invisible Black Background
An example image is this one:
I have just started using Photoshop, so I am not aware of design techniques and terms. But is there any way (or tutorial better) to replicate this effect in a portrait image with a non-black background?
You can replicate this in Photoshop, but there's no "automatic" and easy ways to do it. It's close to doing digital painting at this point and you need to have some skills in shadow/highlights.
Basically, what you'll need to do to create this effect is:
In your example, the man has only a soft light in front of him. Depending on the picture you'll use to create this effect, you'll need to add the shadows in the back on his body, and on his shoulders.
You should use the same rich black CMYK recipe for your shadows than the one you used for your background.
For the technique, it depends on your skills and preferences. I think what's hard is not how to do it but how to render properly the shadows and highlights. Personally I like to "paint" details with a soft brush, play with my layers transparency, use layers with different blending, and other lighter parts to amplify the reflection of light. I apply myself the shadows where I want to to add a more dramatic effect.
If this can get you started, here is a very quick example I did. I include the layers so you can see how I would process to modify that kind of images. This only took me a few minutes but if you apply yourself in adding nice contrast on your shadows, and if you also have a nice subject, you'll get nicer results.
Original file:
Modified black background:
Subject layer is using "luminosity" blending mode. All the shadows are in "multiply".
Since the light is in front of the subject, I added more shadow on the back of his ear and neck, more light on his collar, and I amplified a bit the folds of his sleeve. It's really not perfect but it gives you an idea how to proceed.
Color subject (layer of subject is not in "luminosity" blending):
As you can see, normal gradients makes the subject looks a bit cartoonish. That's where you'll need some patience to paint the shadows with a smaller brush instead!
