Segmenting of an Image can be done by applying different parts of a texture to Quads.

This can be done by mapping different UV vertex points of an image with a Quad or any other 3d object.

Following script demonstrate the Segmenting of an Image with UV vertex mapping :

// Script to demonstrate Segmenting of a Image.

using UnityEngine;
using System.Collections;

public class TextureSegmenting : MonoBehaviour
{

    public Material mat ;
    public Texture2D tex ;
    public int rows ;
    public int cols ;
    void Start ()
    {
        mat.mainTexture = tex; // Appling Texture to material ;

        BuildPieces ();
    }    

    void BuildPieces()
    {
        Vector3 offset = Vector3.zero;         // A Vecter3 viariable for postioning

        // Offset for Placement of tiles
        offset.x = -Mathf.RoundToInt ((float)cols / 2.0f - 0.5f);
        offset.y = -Mathf.RoundToInt ((float)rows / 2.0f - 0.5f);
        float startX = offset.x;
        float uvWidth = 1.0f / cols;  
        float uvHeight = 1.0f / rows;
        
        
        for (int i = 0; i < rows; i++)
        {
            for (int j = 0; j < cols; j++)
            {
                // Creating a primitive Quad
                GameObject quad = GameObject.CreatePrimitive (PrimitiveType.Quad);
                quad.tag ="Player";
                Transform t = quad.transform;
                t.position = offset;
                t.localScale = new Vector3(0.95f, 0.95f, 0.95f);
                quad.renderer.material = mat;
                

                // Getting mesh component of the "quad"
                Mesh mesh = quad.GetComponent<MeshFilter>().mesh;
                Vector2[] uvs = mesh.uv;  // Getting UV vertices from mesh

                // Mapping each UV vertex of quad with texture coordinates
                uvs[0] = new Vector2(j * uvWidth, i * uvHeight);
                uvs[1] = new Vector2((j + 1) * uvWidth, (i + 1) * uvHeight);
                uvs[2] = new Vector2((j + 1) * uvWidth, i * uvHeight);
                uvs[3] = new Vector2(j * uvWidth, (i + 1) * uvHeight);

                // Setting UV vertices back to mesh
                mesh.uv = uvs;
                offset.x += 1.0f;
            }
            offset.y += 1.0f;
            offset.x = startX;
        }
    }
}