You should format your files to serialize, beyond you dont need to pass bytes, just load the image.

 private Texture2D myGUITexture;
 void Start()
 {
     myGUITexture = (Texture2D)Resources.Load("Texturename.png");
 }

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour {
    void Start() {
        GameObject go = GameObject.CreatePrimitive(PrimitiveType.Plane);
        Renderer rend = go.GetComponent<Renderer>();
        rend.material.mainTexture = Resources.Load("glass") as Texture;
    }
}

a bit sorry for this lazy post,
but read the documentation.

then assign to object.
I guess they transfer to bytes because of the resizing.