A 16 bit color texture format.

	function Start () {
		// Create a new 16 bits per pixel texture and assign it
		// to the renderer's material
		var texture = new Texture2D (128, 128, TextureFormat.RGB565, false);
		renderer.material.mainTexture = texture;
	}

using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void Start() {
        Texture2D texture = new Texture2D(128, 128, TextureFormat.RGB565, false);
        renderer.material.mainTexture = texture;
    }
}

import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def Start() as void:
		texture as Texture2D = Texture2D(128, 128, TextureFormat.RGB565, false)
		renderer.material.mainTexture = texture