A 16 bits/pixel texture format. Texture stores color with an alpha channel.

	function Start () {
		// Create a new 16 bits per pixel texture with an alpha channel and assign it
		// to the renderer's material
		var texture = new Texture2D (128, 128, TextureFormat.ARGB4444, false);
		renderer.material.mainTexture = texture;
	}

using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void Start() {
        Texture2D texture = new Texture2D(128, 128, TextureFormat.ARGB4444, 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.ARGB4444, false)
		renderer.material.mainTexture = texture