"Scale2x" sample code and project

I once needed pixel scaling algorithm for one test scene, so I ported Scale2x to Unity C# that uses Texture operations for the job. Since the Scale2x author has following disclaimer Instead, you are free to use the algorithm, but please call the effect "Scale2x", I am calling this "Scale2x".

Since Color components are floats, the comparison of colors is done somewhat cumbersomely, but it works. And if you want to use this, make sure the Read/Write enabled is checked from texture import settings (also set the Filter mode: Point).

Sample shot:


(sample textures are from BrowserQuest and they are under CC-BY-SA 3.0)

Unitypackage:
View attachment $_scale2x_.unitypackage

Actual scaling part

Code (csharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public static class Scaledoublex {
5.    
6.     /// <summary>
7.     /// Use "Scale2x" algorithm to produce new texture from inputTexture.
8.     /// </summary>
9.     /// <param name='inputTexture'>
10.     /// Input texture.
11.     /// </param>
12.     public static Texture2D Scale2x(Texture2D inputTexture)
13.     {
14.         Texture2D returnTexture = new Texture2D(inputTexture.width*2, inputTexture.height*2);
15.        
16.         // Every pixel from input texture produces 4 output pixels, for more details check out http://scale2x.sourceforge.net/algorithm.html
17.         int y = 0;
18.         while (y < inputTexture.height)
19.         {
20.             int x = 0;
21.             while (x < inputTexture.width)
22.             {
23.                 Color colorB = inputTexture.GetPixel(x, y-1);
24.                 Color colorH = inputTexture.GetPixel(x, y+1);
25.                 Color colorD = inputTexture.GetPixel(x-1, y);
26.                 Color colorF = inputTexture.GetPixel(x+1, y);
27.                
28.                 Color colorE = inputTexture.GetPixel(x, y);
29.                
30.                 if(!AreColorsSame(colorB, colorH)  !AreColorsSame(colorD, colorF))
31.                 {
32.                     returnTexture.SetPixel(2*x,   2*y,   AreColorsSame(colorD, colorB) ? colorD : colorE);
33.                     returnTexture.SetPixel(2*x+1, 2*y,   AreColorsSame(colorB, colorF) ? colorF : colorE);
34.                     returnTexture.SetPixel(2*x,   2*y+1, AreColorsSame(colorD, colorH) ? colorD : colorE);
35.                     returnTexture.SetPixel(2*x+1, 2*y+1, AreColorsSame(colorH, colorF) ? colorF : colorE);
36.                 }
37.                 else
38.                 {
39.                     returnTexture.SetPixel(2*x,   2*y, colorE);
40.                     returnTexture.SetPixel(2*x+1, 2*y, colorE);
41.                     returnTexture.SetPixel(2*x,   2*y+1, colorE);
42.                     returnTexture.SetPixel(2*x+1, 2*y+1, colorE);
43.                 }
44.                
45.                 x++;
46.             }
47.             y++;
48.            
49.         }
50.        
51.         returnTexture.Apply(false, true);
52.         return returnTexture;
53.     }
54.    
55.     /// <summary>
56.     /// Checks if the colors are the same.
57.     /// </summary>
58.     /// <returns>
59.     /// True if they are; otherwise false
60.     /// </returns>
61.     /// <param name='a'>
62.     /// First color.
63.     /// </param>
64.     /// <param name='b'>
65.     /// Second color.
66.     /// </param>
67.     private static bool AreColorsSame(Color aColor, Color bColor)
68.     {
69.         return Mathf.Approximately(aColor.r, bColor.r)  Mathf.Approximately(aColor.g, bColor.g)  Mathf.Approximately(aColor.b, bColor.b)  Mathf.Approximately(aColor.a, bColor.a);
70.     }
71. }

and usage

Code (csharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class Controller : MonoBehaviour {
5.    
6.     public Texture2D house;
7.     public Texture2D skull;
8.    
9.     private Texture2D scale2Xhouse;
10.     private Texture2D scale2Xskull;
11.    
12.     // Use this for initialization
13.     void Start () {
14.         scale2Xhouse = Scaledoublex.Scale2x(house);
15.         scale2Xskull = Scaledoublex.Scale2x(skull);
16.     }
17.    
18.     // Update is called once per frame
19.     void Update () {
20.    
21.     }
22.    
23.     void OnGUI() {
24.         // Normal house
25.         GUI.Label(new Rect(10, 0, 100, 20), "Normal");
26.         GUI.DrawTexture(new Rect(5, 20, house.width, house.height), house);
27.        
28.         // 2x house with normal scaling
29.         GUI.Label(new Rect(house.width+20, 0, 100, 20), "Point scale 2x");
30.         GUI.DrawTexture(new Rect(house.width+10, 20, house.width*2, house.height*2), house);
31.        
32.         // 2x house with "scale2x" scaling
33.         GUI.Label(new Rect(3*house.width+30, 0, 100, 20), '"' + "scale2x" + '"');
34.         GUI.DrawTexture(new Rect(3*house.width+20, 20, scale2Xhouse.width, scale2Xhouse.height), scale2Xhouse);
35.        
36.        
37.        
38.         // Normal skull
39.         GUI.Label(new Rect(10, 320, 100, 20), "Normal");
40.         GUI.DrawTexture(new Rect(5, 340, skull.width, skull.height), skull);
41.        
42.         // 2x skull with normal scaling
43.         GUI.Label(new Rect(skull.width+20, 320, 100, 20), "Point scale 2x");
44.         GUI.DrawTexture(new Rect(skull.width+10, 340, skull.width*2, skull.height*2), skull);
45.        
46.         // 2x skull with "scale2x" scaling
47.         GUI.Label(new Rect(3*skull.width+30, 320, 100, 20), '"' + "scale2x" + '"');
48.         GUI.DrawTexture(new Rect(3*skull.width+20, 340, scale2Xskull.width, scale2Xskull.height), scale2Xskull);
49.     }
50. }

 

Thansk! Very good!