avatar.cs

using UnityEngine;
using System.Collections;
using AgencyScripts.Library;

public class Avatar {

	public const int AVATAR_SIZE = 512;

	private Sprite _sprite = null;
	public Sprite Sprite
	{
		get {
			if(_sprite == null)
			{
				_sprite = Sprite.Create(
					Texture, 
					new Rect(0, 0, AVATAR_SIZE, AVATAR_SIZE), 
					new Vector2(0.5f,0.5f), //pivot
					100f);
			}
			return _sprite;
		}
	}

	private Texture2D _texture;
	public Texture2D Texture
	{
		get {
			if(_texture == null)
			{
				_texture = GenerateTexture();
			}
			return _texture;
		}
	}
	private Color32 _blankColor = new Color32();
	private Color32 _mainColor;
	public Color32 MainColor
	{
		get {
			if(_mainColor.SameAs(_blankColor))
				_mainColor = RandomColor.Get ();
			return _mainColor;
		}
	}

	private Color32 _backgroundColor;
	public Color32 BackgroundColor
	{
		get{
			if(_backgroundColor.SameAs(_blankColor))
				_backgroundColor = MainColor.GetComplement();
			return _backgroundColor;
		}
	}

	public Avatar()
	{
		_mainColor = _blankColor;
		_backgroundColor = _blankColor;
	}

	private Texture2D GenerateTexture()
	{
		Texture2D t = new Texture2D(AVATAR_SIZE, AVATAR_SIZE);
		
		Color32[] fillColorArray =  t.GetPixels32();
		
		for(var i = 0; i < fillColorArray.Length; ++i)
		{
			fillColorArray[i] = BackgroundColor;
		}
		
		t.SetPixels32( fillColorArray );

		
		t.Apply(false);
		return t;
	}

}

ImageAssign.cs

...
RawImage image = prefab.transform.Find("imgAgentPicture").GetComponent<RawImage>();
image.texture = agent.Avatar.Texture;
...