使用Arnold的猫贴图进行图像混洗

Question

我正在努力实现2D Arnold的N x M图像的猫地图。问题是我不能得到原始像素的值(例如，Arnold cat map逆不起作用)。任何解决方案从任何自由职业者将支付。我写的VB6.0代码根据二维阿诺德的猫地图方程的洗牌和逆。

Private Sub Cipher()
 Dim Hm As Integer, i As Integer, x As Integer
 Dim Wm As Integer, j As Integer, y As Integer
Wm = Wid - 1: Hm = Hgt - 1
    pic1.ScaleMode = vbPixels
    pic1.ScaleWidth = Wid
    pic1.ScaleHeight = Hgt

Dim pp As Double, qq As Double
Dim nn As Integer, k As Integer
Dim xnn As Double, ynn As Double

pp = 2: qq = 5
nn = 1

For k = 1 To nn
For y = 0 To Hm
For x = 0 To Wm

 '''''''''''' arnold cat map''''''''''''''''''
xnn = x + pp * y
ynn = qq * x + (pp * qq + 1) * y

 xnn = xnn Mod Wm
 ynn = ynn Mod Hm

 Red(xnn, ynn) = Red(x, y)
 Grn(xnn, ynn) = Grn(x, y)
 Blu(xnn, ynn) = Blu(x, y)
    Next x: Next y
'''''''''''' end of shfulling
For y = 0 To Hm: For x = 0 To Wm
pic1.PSet (x, y), RGB(Red(x, y), Grn(x, y), Blu(x, y))
Next x: Next y
pic1.Refresh
Next k
End Sub

这是Arnold cat map的逆向代码：

私有子DeCipher()

 Dim Hm As Integer, i As Integer, x As Integer
 Dim Wm As Integer, j As Integer, y As Integer
Wm = Wid - 1: Hm = Hgt - 1

pic2.ScaleWidth = Wid
pic2.ScaleHeight = Hgt


Dim pp As Double, qq As Double
Dim nn As Integer, k As Integer
Dim xnn As Double, ynn As Double


pp = 2: qq = 5
nn = 1

For k = 1 To nn 'no. of iterations

For y = 0 To Hm
For x = 0 To Wm

 '''''''''''' Inverse of Arnold Cat map''''''''''''''''''
 xnn = Abs((x * ((pp * qq) + 1)) + (-pp * y))
 ynn = Abs((-qq * x) + y)

 xnn = xnn Mod Wm
 ynn = ynn Mod Hm
 '''''''''''''''''''''''''''''''''''''''''''''
Red(xnn, ynn) = Red(x, y)
 Grn(xnn, ynn) = Grn(x, y)
 Blu(xnn, ynn) = Blu(x, y)
    Next x: Next y
'''''''''''' end of shuffling
Next k

For y = 0 To Hm: For x = 0 To Wm
pic2.PSet (x, y), RGB(Red(x, y), Grn(x, y), Blu(x, y))

Next x: Next y
End Sub

Answer 1

这项任务是不可能的，因为您在编码时覆盖了像素。被重写的信息被擦除并且不能被重建。如果您要更改编码代码以使原始末端编码图像具有不同的颜色阵列，

CodeRed(xnn, ynn) = OrigRed(x, y)
CodeGrn(xnn, ynn) = OrigGrn(x, y)
CodeBlu(xnn, ynn) = OrigBlu(x, y)

然后，您可以使用与前向循环中相同的索引计算，只需向后复制，

For k = 1 To nn
For y = 0 To Hm
For x = 0 To Wm

   '''''''''''' arnold cat map''''''''''''''''''
  xnn = x + pp * y
  ynn = qq * x + (pp * qq + 1) * y

  xnn = xnn Mod Wm
  ynn = ynn Mod Hm

  OrigRed(x, y) = CodeRed(xnn, ynn)
  OrigGrn(x, y) = CodeGrn(xnn, ynn)
  OrigBlu(x, y) = CodeBlu(xnn, ynn)

Next x: Next y