To evaluate $f(4)$ from the given graph, you would need to locate $x = 4$ on the horizontal axis and observe the corresponding $y$-value of the function $f(x)$ at this point. From the graph provided:

1. At $x = 4$, the green horizontal line segment corresponds to the function value. The $y$-value remains constant along this segment.
2. Observing the graph, $f(4) = 2$.

Thus, the value of $f(4)$ is 2.

Do you want me to explain further or analyze the graph in detail? Here are some related questions to explore:

1. What is the behavior of the function for other intervals of $x$?
2. What is the domain and range of the function $f(x)$?
3. Can you explain the significance of the different line segments on the graph (red, green, blue)?
4. How would $f(x)$ change if additional transformations were applied?
5. What are the points of discontinuity or sharp changes in the graph?

Tip: Always check for breaks or jumps in the graph to evaluate piecewise-defined functions accurately.