Change Canvas Image from Another Script

So I am trying to change a canvas's image to red if there has been a collision with the player. I have a canvas with an image component, with "Source Image" set to a transparent square that I made in photoshop. I want to change it to another red square that I made in photoshop vi my PlayerBehavior script if there has been a collision. This is what I tried:

 using UnityEngine;
 using System.Collections;
 using UnityEngine.UI;

 public class PlayerBehavior : MonoBehaviour {
     Image image;
     void start() { }
     void update() {}

     void OnTriggerEnter2D(Collider2D other) {
     if (other.tag == "bullet") {
         Canvas canvas = GetComponent<Canvas>();
         image = canvas.GetComponent<Image>();
         image.sprite = Resources.Load ("flashred.png");
     }

 }

}

I am getting this error:

 Error CS0266: Cannot implicitly convert type `UnityEngine.Object' to     `UnityEngine.Sprite'. An explicit conversion exists (are you missing a cast?)     (CS0266) (Assembly-CSharp)