Patent ID: 11902430
Assignee: SHANGHAI MARITIME UNIVERSITY
Field: Audio-visual technology (Electrical engineering)
Classification: CPC H  G | IPC G  H

Claim 3:
4. The quantum color image encrypting method based on modification direction according to claim 3, wherein:
the comparing whether the value of secret data is equal to the value of the first extract function comprises:
comparing the value of the first extract function FXY and the value of the secrete data DYX, and computing the difference SYX therebetween, then:, S
    
      Y
      ⁢
      X
    
  
  =
  
    {
    
      
        
          
            
              
                D
                YX
              
              -
              
                F
                YX
              
            
            ,
            
              
            
            ⁢
            
              
                if
                ⁢
                
                  
                
                ⁢
                
                  D
                  
                    Y
                    ⁢
                    X
                  
                
              
              >
              
                F
                YX
              
            
          
        
      
      
        
          
            
              
                F
                YX
              
              -
              
                D
                YX
              
            
            ,
            
              
            
            ⁢
            
              
                if
                ⁢
                
                  
                
                ⁢
                
                  D
                  
                    Y
                    ⁢
                    X
                  
                
              
              <
              
                F
                YX
              
            
          
        
      
    
  

where DYX=wyx1wyx2, DYX∈{0,1, 2, 3}; wyx1 and wyx2), represent the bits of the secret data in position (Y, X), respectively;
if DYX=FYX, no modification made to pixel group [|gYX1,|gYX2] in the carrier image;
if DYX>FYX, further comparing between the difference SYX and 2, and defining the modification to the pixel group [|gYX1,|gXY2] as:, if DYX > FYX

 SYX = DYX − FYX;

 if SYX ≤ 2

  gYXSYX = gYXSYX +1;

 else

  gYX4-SYX = gYX4-SYX −1;

 end

end

if DYX<FYX, defining modification to the pixel group [|gYX1,|gYX2] as:, if DYX < FYX

 SYX = FYX − DYX;

 if SYX ≤ 2

  gYXSYX = gYXSYX −1;

 else

  gYX4-SYX = gYX4-SYX +1;

 end

end.