Creating the color image

The input data in this process consists of the luminance and the chrominance images. Both are stored in real-valued, normalized matrices (respectively L and C). The output will be a RGB image with three components: R,G and B, obtained by transforming a NTSC image composed of the matrices Y, I and Q. The first step is thus transforming L and C into the NTSC components Y, I and Q through a colormap operator (actually, a set of three related operators)

 

Y=M₁L

 

I=M₂C

 

Q=M₃C

The next section will elaborate on the construction of the three operators. Once the Y, I and Q matrices are obtained, we basically have the color image, but since computer devices work with RGB, we usually need to transform to RGB with the equation  

$$\left[ \matrix { R \cr G \cr B} \right] = \left[ \matr... ...703 } \right] \ \ \left[ \matrix { Y \cr I \cr Q} \right]$$ (4)

before writing the file to disk Kuhn (1996).

 

jetcolormap
Figure 1 The main part of the operators M₁, M₂ and M₃ consists of the transformation from RGB to NTSC of a common colormap