Transform an image from an arbitrary color space to the RGB color space.

::trans_to_rgb transforms an image from an arbitrary color space (ColorSpace) to the RGB color space. The three channels of the image are passed as three separate images on input and output.

The following transformations are supported:

  'yiq'
     |R|   |0.999   0.962   0.615|   |Y|
     |G| = |0.949  -0.220  -0.732| * |I|
     |B|   |0.999  -1.101   1.706|   |Q|

  'argyb'
     |R|   |1.00   1.29   0.22|   |A |
     |G| = |1.00  -0.71   0.22| * |Rg|
     |B|   |1.00   0.29  -1.78|   |Yb|

  'ciexyz'
     |R|   | 2.750  -1.149  -0.426|   |X|
     |G| = |-1.118   2.026   0.033| * |Y|
     |B|   | 0.138  -0.333   1.104|   |Z|

  'hls'
     Hi = integer(H * 6)
     Hf = fraction(H * 6)
     if (L <= 0.5)
        max = L * (S + 1)
     else
        max = L + S - (L * S)
     fi
     min = 2 * L - max
     if (S == 0)
        R = L
        G = L
        B = L
     else
       if (Hi == 0)
          R = max
          G = min + Hf * (max - min)
          B = min
       elif (Hi == 1)
          R = min + (1 - Hf) * (max - min)
          G = max
          B = min
       elif (Hi == 2)
          R = min
          G = max
          B = min + Hf * (max - min)
       elif (Hi == 3)
          R = min
          G = min + (1 - Hf) * (max - min)
          B = max
       elif (Hi == 4)
          R = min + Hf * (max - min)
          G = min
          B = max
       elif (Hi == 5)
          R = max
          G = min
          B = min + (1 - Hf) * (max - min)
       fi
     fi           

  'hsi'
     M1 = S * sin(H)
     M2 = S * cos(H)
     I1 = I / sqrt(3)
     |R|   | 2/sqrt(6)   0           1/sqrt(3)|   |M1|
     |G| = |-1/sqrt(6)   1/sqrt(2)   1/sqrt(3)| * |M2|
     |B|   |-1/sqrt(6)  -1/sqrt(2)   1/sqrt(3)|   |I1|

  'hsv'
     if (S == 0)
        if (H == 0)
           R = V
           G = V
           B = V
        else
           R = 0
           G = 0
           B = 0
        fi
     else
        Hi = integer(H)
        Hf = fraction(H)
        if (Hi == 0)
           R = V
           G = V * (1 - (S * (1 - Hf)))
           B = V * (1 - S)
        elif (Hi == 1)
           R = V * (1 - (S * Hf))
           G = V
           B = V * (1 - S)
        elif (Hi == 2)
           R = V * (1 - S)
           G = V
           B = V * (1 - (S * (1 - Hf)))
        elif (Hi == 3)
           R = V * (1 - S)
           G = V * (1 - (S * Hf))
           B = V
        elif (Hi == 4)
           R = V * (1 - (S * (1 - Hf)))
           G = V * (1 - S)
           B = V
        elif (Hi == 5)
           R = V
           G = V * (1 - S)
           B = V * (1 - (S * Hf))
        fi
     fi

/* Tranformation from rgb to hsv and conversely */
read_image(Image,"patras") ;
disp_color(Image,WindowHandle) ;
decompose3(Image,&Rimage,&Gimage,&Bimage) ;
trans_from_rgb(Rimage,Gimage,Bimage,&Image1,&Image2,&Image3,"hsv") ;
trans_to_rgb(Image1,Image2,Image3,&ImageRed,&ImageGreen,&ImageBlue,"hsv") ;
compose3(ImageRed,ImageGreen,ImageBlue,&Multichannel) ;
disp_color(Multichannel,WindowHandle);

::trans_to_rgb returns H_MSG_TRUE if all parameters are correct. If the input is empty the behaviour can be set via ::set_system('no_object_result',<Result>). If necessary, an exception handling is raised.

::decompose3

::compose3, ::disp_color

::decompose3

Image filters