Color Space Conversion

Convert color space of image

• 

Libraries:
Computer Vision Toolbox / Conversions

Description

The Color Space Conversion block converts color information between color spaces. Use the Conversion parameter to specify the color spaces you are converting between.

Examples

Convert Image Color Space from RGB to YCbCr

Convert an image color space from RGB to YCbCr.

• Open Script

Ports

Input

Port_1 — Input image

array

Input image, specified as an M-by-N-by-C array, where C is the number of color channels in the input image.

Data Types: single | double | uint8

R' — Red color component of image

matrix

Red color component of image, specified as an M-by-N matrix.

Note

Inputs to the R', G', and B' ports must have the same dimensions and data type as one another.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to one of these options:

• R'G'B' to Y'CbCr

• R'G'B' to intensity

• R'G'B' to HSV

• sR'G'B' to XYZ

• sR'G'B' to L*a*b*

Data Types: single | double | uint8

G' — Green color component of image

matrix

Green color component of image, specified as an M-by-N matrix.

Note

Inputs to the R', G', and B' ports must have the same dimensions and data type as one another.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to one of these options:

• R'G'B' to Y'CbCr

• R'G'B' to intensity

• R'G'B' to HSV

• sR'G'B' to XYZ

• sR'G'B' to L*a*b*

Data Types: single | double | uint8

B' — Blue color component of image

matrix

Blue color component of image, specified as an M-by-N matrix.

Note

Inputs to the R', G', and B' ports must have the same dimensions and data type as one another.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to one of these options:

• R'G'B' to Y'CbCr

• R'G'B' to intensity

• R'G'B' to HSV

• sR'G'B' to XYZ

• sR'G'B' to L*a*b*

Data Types: single | double | uint8

Y' — Luma component of image

matrix

Luma component of image, specified as an M-by-N matrix.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to Y'CbCr to R'G'B'.

Data Types: single | double | uint8

Cb — Blue-difference chroma component of image

matrix

Blue-difference chroma component of image, specified as an M-by-D matrix, where D is half the width of the image.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to Y'CbCr to R'G'B'.

Data Types: single | double | uint8

Cr — Red-difference chroma component of image

matrix

Red-difference chroma component of image, specified as an M-by-D matrix, where D is half the width of the image.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to Y'CbCr to R'G'B'.

Data Types: single | double | uint8

H — Hue component of image

matrix

Hue component of image, specified as an M-by-N matrix.

Note

Inputs to the H, S, and V ports must have the same dimensions and data type as one another.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to HSV to R'G'B'.

Data Types: single | double

S — Saturation component of image

matrix

Saturation component of image, specified as an M-by-N matrix.

Note

Inputs to the H, S, and V ports must have the same dimensions and data type as one another.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to HSV to R'G'B'.

Data Types: single | double

V — Brightness component of image

matrix

Brightness component of image, specified as an M-by-N matrix.

Note

Inputs to the H, S, and V ports must have the same dimensions and data type as one another.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to HSV to R'G'B'.

Data Types: single | double

X — X component of image

matrix

X component of image, specified as an M-by-N matrix.

Note

Inputs to the X, Y, and Z ports must have the same dimensions and data type as one another.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to XYZ to sR'G'B'.

Data Types: single | double

Y — Y component of image

matrix

Y component of image, specified as an M-by-N matrix.

Note

Inputs to the X, Y, and Z ports must have the same dimensions and data type as one another.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to XYZ to sR'G'B'.

Data Types: single | double

Z — Z component of image

matrix

Z component of image, specified as an M-by-N matrix.

Note

Inputs to the X, Y, and Z ports must have the same dimensions and data type as one another.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to XYZ to sR'G'B'.

Data Types: single | double

L* — Lightness component of image

matrix

Lightness component of image, specified as an M-by-N matrix.

Note

Inputs to the L*, a*, and b* ports must have the same dimensions and data type as one another.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to L*a*b* to sR'G'B'.

Data Types: single | double

a* — Red-green component of image

M-by-N matrix

Red-green component of image, specified as an M-by-N matrix.

Note

Inputs to the L*, a*, and b* ports must have the same dimensions and data type as one another.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to L*a*b* to sR'G'B'.

Data Types: single | double

b* — Yellow-blue component of image

M-by-N matrix

Yellow-blue component of image, specified as an M-by-N matrix.

Note

Inputs to the L*, a*, and b* ports must have the same dimensions and data type as one another.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to L*a*b* to sR'G'B'.

Data Types: single | double

Output

Port_1 — Output image

array

Output image, returned as an M-by-N-by-P array, where P is the number of color channels in the output image. For Y'CbCr output, the value range for the Y component differs from those of the Cb and Cr components.

• If the input is uint8, then Y'CbCr is uint8. Y' is in the range [16, 235], and Cb and Cr are in the range [16, 240].

• If the input is double, then Y'CbCr is double. Y' is in the range [16/255, 235/255], and Cb and Cr are in the range [16/255, 240/255].

Data Types: single | double | int8 | uint8

R' — Red color component of image

matrix

Red color component of image, returned as an M-by-N matrix.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to one of these options:

• Y'CbCr to R'G'B'

• HSV to R'G'B'

• XYZ to sR'G'B'

• L*a*b* to sR'G'B'

.

Data Types: single | double | int8 | uint8

G' — Green color component of image

matrix

Green color component of image, returned as an M-by-N matrix.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to one of these options:

• Y'CbCr to R'G'B'

• HSV to R'G'B'

• XYZ to sR'G'B'

• L*a*b* to sR'G'B'

Data Types: single | double | int8 | uint8

B' — Blue color component of image

matrix

Blue color component of image, returned as an M-by-N matrix.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to one of these options:

• Y'CbCr to R'G'B'

• HSV to R'G'B'

• XYZ to sR'G'B'

• L*a*b* to sR'G'B'

.

Data Types: single | double | int8 | uint8

Y' — Luma component of image

matrix

Luma component of image, returned as an M-by-N matrix.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to R'G'B' to Y'CbCr.

Data Types: single | double | int8 | uint8

Cb — Blue-difference chroma component of image

matrix

Blue-difference chroma component of image, returned as an M-by-N matrix.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to R'G'B' to Y'CbCr.

Data Types: single | double | int8 | uint8

Cr — Red-difference chroma component of image

matrix

Red-difference chroma component of image, returned as an M-by-N matrix.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to R'G'B' to Y'CbCr.

Data Types: single | double | int8 | uint8

I' — Intensity image

matrix

Intensity image, returned as an M-by-N matrix.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to R'G'B' to intensity.

Data Types: single | double | int8 | uint8

H — Hue component of image

matrix

Hue component of image, returned as an M-by-N matrix.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to R'G'B' to HSV.

Data Types: single | double

S — Saturation component of image

matrix

Saturation component of image, returned as an M-by-N matrix.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to R'G'B' to HSV.

Data Types: single | double

V — Brightness component of image

matrix

Brightness component of image, returned as an M-by-N matrix.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to R'G'B' to HSV.

Data Types: single | double

X — X component of image

matrix

X component of image, returned as an M-by-N matrix.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to sR'G'B' to XYZ.

Data Types: single | double

Y — Y component of image

matrix

Y component of image, returned as an M-by-N matrix.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to sR'G'B' to XYZ.

Data Types: single | double

Z — Z component of image

matrix

Z component of image, returned as an M-by-N matrix.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to sR'G'B' to XYZ.

Data Types: single | double

L* — Lightness component of image

matrix

Lightness component of image, returned as an M-by-N matrix.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to sR'G'B' to L*a*b*.

Data Types: single | double

a* — Red-green component of image

matrix

Red-green component of image, returned as an M-by-N matrix.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to sR'G'B' to L*a*b*.

Data Types: single | double

b* — Yellow-blue component of image

matrix

Yellow-blue component of image, returned as an M-by-N matrix.

Dependencies

To enable this port, set the Image signal parameter to Separate color signals and set the Conversion parameter to sR'G'B' to L*a*b*.

Data Types: single | double

Parameters

Conversion — Color space conversion

R'G'B' to Y'CbCr (default) | Y'CbCr to R'G'B' | R'G'B' to intensity | ...

Specify which color space to convert the image from and to using these options:

• R'G'B' to Y'CbCr

• Y'CbCr to R'G'B'

• R'G'B' to intensity

• B'G'R' to intensity

• B'G'R' to R'G'B'

• R'G'B' to B'G'R'

• R'G'B' to HSV

• HSV to R'G'B'

• sR'G'B' to XYZ

• XYZ to sR'G'B'

• sR'G'B' to L*a*b*

• L*a*b* to sR'G'B'

Note

The prime notation indicates that the signal is gamma corrected.

Use conversion specified by — Color conversion standard

Rec. 601 (SDTV) (default) | Rec. 709 (HDTV)

Specify the color conversion standard for converting the image between the R'G'B' and Y'CbCr color spaces as either Rec. 601 (SDTV) or Rec. 709 (HDTV).

Dependencies

To enable this parameter, set the Conversion parameter to R'G'B' to Y'CbCr or Y'CbCr to R'G'B'.

Scanning standard — Scanning standard

1125/60/2:1 (default) | 1250/50/2:1

Specify the scanning standard for converting the image between the R'G'B' and Y'CbCr color spaces as either 1125/60/2:1 or 1250/50/2:1.

Dependencies

To enable this parameter, set the Conversion parameter to R'G'B' to Y'CbCr or Y'CbCr to R'G'B' and set the Use conversion specified by parameter to Rec. 709 (HDTV).

White point — White point

D50 (default) | D55 | D65

Specify the reference white point for converting the image between the sR'G'B' and L*a*b* color spaces as D50, D55, or D65.

Dependencies

To enable this parameter, set the Conversion parameter to sR'G'B' to L*a*b* or L*a*b* to sR'G'B'.

Image signal — Image signal input

One multidimensional signal (default) | Separate color signals

Specify whether to combine the color channels of the image into one signal or input and output them individually.

• One multidimensional signal — The block accepts all color channels of the input image as a multidimensional array to a single input port, and outputs the converted image as a single matrix or array from a single output port.

• Separate color signals — The block accepts each color channel of the input image to a separate input port, and outputs each color channel of the converted image from a separate output port.

Block Characteristics

Data Types	Boolean | double | integer | single | image
Multidimensional Signals	yes
Variable-Size Signals	yes

Algorithms

Conversion Between R'G'B' and Y'CbCr Color Spaces

These equations define R'G'B' to Y'CbCr conversion and Y'CbCr to R'G'B' conversion, respectively:

$$\left[\begin{array}{c}{Y}^{\prime }\\ Cb\\ Cr\end{array}\right]=\left[\begin{array}{c}16\\ 128\\ 128\end{array}\right]+{\rm A}\times \left[\begin{array}{c}{R}^{\prime }\\ G^{\prime }\\ B^{\prime }\end{array}\right]$$

$$\left[\begin{array}{c}{R}^{\prime }\\ G^{\prime }\\ B^{\prime }\end{array}\right]={\rm B}\times \left(\left[\begin{array}{c}{Y}^{\prime }\\ Cb\\ Cr\end{array}\right]-\left[\begin{array}{c}16\\ 128\\ 128\end{array}\right]\right)$$

The values in matrices A and B are based on your choices for the Use conversion specified by and Scanning standard parameters.

Matrix	Use conversion specified by = Rec. 601 (SDTV)	Use conversion specified by = Rec. 709 (HDTV)
		Scanning standard = 1125/60/2:1	Scanning standard = 1250/50/2:1
A	$$\left[\begin{array}{ccc}0.25678824& 0.50412941& 0.09790588\\ -0.1482229& -0.29099279& 0.43921569\\ 0.43921569& -0.36778831& -0.07142737\end{array}\right]$$	$$\left[\begin{array}{l}\text{ 0}\text{.18258588 0}\text{.61423059 0}\text{.06200706}\\ \text{ -0}\text{.10064373 -0}\text{.33857195 0}\text{.43921569}\\ \text{ 0}\text{.43921569 -0}\text{.39894216 -0}\text{.04027352}\end{array}\right]$$	$$\left[\begin{array}{ccc}0.25678824& 0.50412941& 0.09790588\\ -0.1482229& -0.29099279& 0.43921569\\ 0.43921569& -0.36778831& -0.07142737\end{array}\right]$$
B	$$\left[\begin{array}{ccc}1.1643836& 0& 1.5960268\\ 1.1643836& -0.39176229& -0.81296765\\ 1.1643836& 2.0172321& 0\end{array}\right]$$	$$\left[\begin{array}{ccc}\text{1}\text{.16438356}& \text{0}& \text{1}\text{.79274107}\\ \text{1}\text{.16438356}& \text{-0}\text{.21324861}& \text{-0}\text{.53290933}\\ \text{1}\text{.16438356}& \text{2}\text{.11240179}& \text{0}\end{array}\right]$$	$$\left[\begin{array}{ccc}1.1643836& 0& 1.5960268\\ 1.1643836& -0.39176229& -0.81296765\\ 1.1643836& 2.0172321& 0\end{array}\right]$$

Conversion from R'G'B' to Intensity

This equation defines conversion from the R'G'B' color space to an intensity image:

$$\text{intensity}=\left[\begin{array}{ccc}0.299& 0.587& 0.114\end{array}\right]\left[\begin{array}{c}{R}^{\prime }\\ G^{\prime }\\ B^{\prime }\end{array}\right]$$

Conversion from B'G'R' to Intensity

This equation defines conversion from the B'G'R' color space to an intensity image:

$$\text{intensity}=\left[\begin{array}{ccc}0.114& 0.587& 0.2999\end{array}\right]\left[\begin{array}{c}B\text{'}\\ G^{\prime }\\ R\text{'}\end{array}\right]$$

Conversion Between R'G'B' and HSV Color Spaces

In the equations defining the R'G'B' to HSV conversion, MAX and MIN are the highest and lowest component values, respectively, of a given R'G'B' triplet. H, S, and V vary from 0 to 1.

$$\begin{array}{l}H=\{\begin{array}{c}\left(\frac{G^{\prime }-B^{\prime }}{MAX-MIN}\right)/6,\begin{array}{cc}\begin{array}{cc}\begin{array}{cc}& \text{if}\end{array}& R^{\prime }=MAX\end{array}& \end{array}\\ \left(2+\frac{B^{\prime }-R^{\prime }}{MAX-MIN}\right)/6,\begin{array}{cc}\begin{array}{cc}\begin{array}{cc}& \text{if}\end{array}& G^{\prime }=MAX\end{array}& \end{array}\\ \left(4+\frac{R^{\prime }-G^{\prime }}{MAX-MIN}\right)/6,\begin{array}{cc}\begin{array}{cc}\begin{array}{cc}& \text{if}\end{array}& B^{\prime }=MAX\end{array}& \end{array}\end{array}\\ S=\frac{MAX-MIN}{MAX}\\ V=MAX\end{array}$$

This equation defines the HSV to R'G'B' conversion, where M is the highest value among $$R_{\text{tmp}}$$, $$G_{\text{tmp}}$$ and $$B_{\text{tmp}}$$:

$$\begin{array}{l}{H}_i=\lfloor 6H\rfloor \\ f=6H-H_i\\ p=1-S\\ q=1-(f*S)\\ t=1-S(1-f)\\ \begin{array}{cc}\text{if}& H_{\text{i}}=0,\begin{array}{cccc}& R_{\text{tmp}}=1,& G_{\text{tmp}}=t,& B_{\text{tmp}}=p\end{array}\end{array}\\ \begin{array}{cc}\text{if}& H_{\text{i}}=1,\begin{array}{cccc}& R_{\text{tmp}}=q,& G_{\text{tmp}}=1,& B_{\text{tmp}}=p\end{array}\end{array}\\ \begin{array}{cc}\text{if}& H_{\text{i}}=2,\begin{array}{cccc}& R_{\text{tmp}}=p,& G_{\text{tmp}}=1,& B_{\text{tmp}}=t\end{array}\end{array}\\ \begin{array}{cc}\text{if}& H_{\text{i}}=3,\begin{array}{cccc}& R_{\text{tmp}}=p,& G_{\text{tmp}}=q,& B_{\text{tmp}}=1\end{array}\end{array}\\ \begin{array}{cc}\text{if}& H_{\text{i}}=4,\begin{array}{cccc}& R_{\text{tmp}}=t,& G_{\text{tmp}}=p,& B_{\text{tmp}}=1\end{array}\end{array}\\ \begin{array}{cc}\text{if}& H_{\text{i}}=5,\begin{array}{cccc}& R_{\text{tmp}}=1,& G_{\text{tmp}}=p,& B_{\text{tmp}}=q\end{array}\end{array}\\ u=V/M\\ R^{\prime }=u*R_{\text{tmp}}\\ G^{\prime }=u*G_{\text{tmp}}\\ B^{\prime }=u*B_{\text{tmp}}\end{array}$$

Conversion Between sR'G'B' and XYZ Color Spaces

The sR'G'B' to XYZ conversion is a two-step process. First, the block converts the gamma-corrected sR'G'B' values to linear sRGB values using these equations:

If $$R_{\text{sRGB}\text{}}^{\text{'}}$$, $$G_{\text{sRGB}}^{\text{'}}$$, and $$B_{\text{sRGB}}^{\text{'}}$$ are each less than or equal to 0.03928, then:

$$\begin{array}{l}{R}_{\text{sRGB}}={R^{\prime }}_{\text{sRGB}}/12.92\\ G_{\text{sRGB}}={G^{\prime }}_{\text{sRGB}}/12.92\\ B_{\text{sRGB}}={B^{\prime }}_{\text{sRGB}}/12.92\end{array}$$

Otherwise:

$$\begin{array}{l}{R}_{\text{sRGB}}={\left[\raisebox{1ex}{$({R^{\prime }}_{\text{sRGB}}+0.055)$}\!\left/ \!\raisebox{-1ex}{$1.055$}\right.\right]}^{2.4}\\ G_{\text{sRGB}}={\left[\raisebox{1ex}{$({G^{\prime }}_{\text{sRGB}}+0.055)$}\!\left/ \!\raisebox{-1ex}{$1.055$}\right.\right]}^{2.4}\\ B_{\text{sRGB}}={\left[\raisebox{1ex}{$({B^{\prime }}_{\text{sRGB}}+0.055)$}\!\left/ \!\raisebox{-1ex}{$1.055$}\right.\right]}^{2.4}\end{array}$$

Then, the block converts the sRGB values to XYZ values using this equation:

$$\left[\begin{array}{c}X\\ Y\\ Z\end{array}\right]=\left[\begin{array}{ccc}0.41239079926596& 0.35758433938388& 0.18048078840183\\ 0.21263900587151& 0.71516867876776& 0.07219231536073\\ 0.01933081871559& 0.11919477979463& 0.95053215224966\end{array}\right]\times \left[\begin{array}{c}{R}_{sRGB}\\ G_{sRGB}\\ B_{sRGB}\end{array}\right]$$

The XYZ to sR'G'B' conversion is also a two-step process. First, the block converts the XYZ values to linear sRGB values using this equation:

$$\left[\begin{array}{c}{R}_{sRGB}\\ G_{sRGB}\\ B_{sRGB}\end{array}\right]={\left[\begin{array}{ccc}0.41239079926596& 0.35758433938388& 0.18048078840183\\ 0.21263900587151& 0.71516867876776& 0.07219231536073\\ 0.01933081871559& 0.11919477979463& 0.95053215224966\end{array}\right]}^{-1}\times \left[\begin{array}{c}X\\ Y\\ Z\end{array}\right]$$

Then the block applies gamma correction, using these equations, to obtain the sR'G'B' values:

If $$R_{\text{sRGB}}$$, $$G_{\text{sRGB}}$$ and $$B_{\text{sRGB}}$$ are each less than or equal to 0.00304, then:

$$\begin{array}{l}{R^{\prime }}_{\text{sRGB}}=12.92R_{\text{sRGB}}\\ {G^{\prime }}_{\text{sRGB}}=12.92G_{\text{sRGB}}\\ {B^{\prime }}_{\text{sRGB}}=12.92B_{\text{sRGB}}\end{array}$$

Otherwise:

$$\begin{array}{l}{R^{\prime }}_{\text{sRGB}}=1.055R_{\text{sRGB}}{}^{(1.0/2.4)}-0.055\\ {G^{\prime }}_{\text{sRGB}}=1.055G_{\text{sRGB}}{}^{(1.0/2.4)}-0.055\\ {B^{\prime }}_{\text{sRGB}}=1.055B_{\text{sRGB}}{}^{(1.0/2.4)}-0.055\end{array}$$

Note

Computer Vision Toolbox™ uses a D65 white point, which is specified in Recommendation ITU-R BT.709, for this conversion. In contrast, the Image Processing Toolbox™ conversion is based on ICC profiles, and it uses a D65 to D50 Bradford adaptation transformation to the D50 white point. If you are using these two products and comparing results, you must account for this difference.

Conversion Between sR'G'B' and L*a*b* Color Spaces

The Color Space Conversion block converts sR'G'B' values to L*a*b* values in two steps. First, it converts sR'G'B' to XYZ values using the equations described in Conversion Between sR'G'B' and XYZ Color Spaces. Then, it uses these equations to transform the XYZ values to L*a*b* values. Here, $$X_n$$, $$Y_n$$, and $$Z_n$$ are the tristimulus values of the reference white point you specify using the White point parameter:

If $$Y/Y_{\text{n}}$$ is greater than 0.008856, then:

$$L^{*}=116{(Y/Y_{\text{n}})}^{1/3}-16$$

Otherwise:

$$L^{*}=903.3Y/Y_{\text{n}}$$

$$\begin{array}{l}{a}^{*}=500(f(X/X_{\text{n}})-f(Y/Y_{\text{n}}))\\ b^{*}=200(f(Y/Y_{\text{n}})-f(Z/Z_{\text{n}})),\end{array}$$

If t is greater than 0.008856, then:

$$f(t)=t^{1/3}$$

Otherwise:

$$f(t)=7.787t+16/166$$

The block converts L*a*b* values to sR'G'B' values in two steps, as well. First, the block transforms the L*a*b* values to XYZ values using these equations:

If $$Y/Y_{\text{n}}$$ is greater than 0.008856, then:

$$\begin{array}{l}X=X_{\text{n}}(P+a^{*}/500{)}^3\\ Y=Y_{\text{n}}{P}^3\\ Z=Z_{\text{n}}(P-b^{*}/200{)}^3,\end{array}$$

where:

$$P=(L^{*}+16)/116$$

Otherwise:

$$\begin{array}{l}X=\raisebox{1ex}{$X_{\text{n}}\left(\left(P+\raisebox{1ex}{$a$}\!\left/ \!\raisebox{-1ex}{$500$}\right.\right)-0.138\right)$}\!\left/ \!\raisebox{-1ex}{$7.787$}\right.\\ Y=\raisebox{1ex}{$Y_{\text{n}}\left(P-0.138\right)$}\!\left/ \!\raisebox{-1ex}{$7.787$}\right.\\ Z=Z_{\text{n}}\left(\left(P-\raisebox{1ex}{$b$}\!\left/ \!\raisebox{-1ex}{$200$}\right.\right)-0.138\right)\left(7.787\right)\end{array}$$

Then it converts XYZ to sR'G'B' values using the equations described in Conversion Between sR'G'B' and XYZ Color Spaces.

References

[1] Poynton, Charles A. A Technical Introduction to Digital Video. New York: John Wiley & Sons, 1996.

[2] International Telecommunication Union (ITU). Studio Encoding Parameters of Digital Television for Standard 4:3 and Wide-Screen 16:9 Aspect Ratios. Recommendation ITU-R BT.601-5. Geneva, Switzerland: ITU, recommended October 1995; superseded January 2007.

[3] International Telecommunication Union (ITU). Parameter Values for the HDTV Standards for Production and International Programme Exchange. Recommendation ITU-R BT.709-5. Geneva, Switzerland: ITU, recommended April 2002; superseded June 2015.

[4] Stokes, Michael, Matthew Anderson, Srinivasan Chandrasekar, and Ricardo Motta. “A Standard Default Color Space for the Internet - sRGB. World Wide Web Consortium (W3C).” November 5, 1996. https://www.w3.org/Graphics/Color/sRGB.html

[5] Berns, Roy S., Fred W. Billmeyer, Max Saltzman, and Fred W. Billmeyer. Billmeyer and Saltzman’s Principles of Color Technology. 3rd ed. New York: Wiley, 2000.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Fixed-Point Conversion
Design and simulate fixed-point systems using Fixed-Point Designer™.

Version History

Introduced before R2006a