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|

  'yuv'
     |R|   |1.0     0.0     1.140|   |Y|
     |G| = |1.0    -0.394  -0.581| * |U|
     |B|   |1.0     2.032   0.0  |   |V|

  '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)
        R = V
        G = V
        B = V
     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

  - Considering byte images, the domain of color space values is generally
    expected to be spread  to the full domain of [0..255]. The origin of 
    signed values must be shifted to 128.

  - Hue values are represented by angles of [0..2PI] and are coded for 
    the particular image types differently:
      + byte-images map the angle domain on [0..255].
      + int4-images are coded in angle minutes [0..21600].
      + real-images are coded in radians [0..2\pi].

  - For int4-images a domain of [0..1] of transformed values 
    imust be spread to [0..10000].

/* 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 2 (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.

trans_to_rgb is reentrant and automatically parallelized (on tuple level, domain level).

decompose3

compose3, disp_color

decompose3

Image filters