Priya R
Updated date Sep 18, 2023
In this blog, we will learn how to convert CMYK to RGB color models in PHP. Explore two methods - manual calculations using formulas and leveraging color libraries.

## Introduction:

Colors play an important role in design, art, and visual communication. Understanding different color models and how to convert between them is crucial for developers and designers alike. In this blog, we will explore the conversion of CMYK (Cyan, Magenta, Yellow, and Key/Black) color model to RGB (Red, Green, Blue) color model using PHP. We'll explore two distinct methods for performing this conversion.

## Method 1: Using Formulas and Scaling

The CMYK and RGB color models are based on different principles. CMYK is a subtractive model used in color printing, while RGB is an additive model employed in electronic displays. Converting between these models requires a series of mathematical operations. The following formulae can be used to convert CMYK to RGB:

• Convert CMYK values to the range of 0 to 1 (by dividing each value by 100).
• Calculate the intermediate values C, M, Y by multiplying (1 - C), (1 - M), and (1 - Y) respectively with (1 - K).
• Calculate the RGB values using the formulas: R = 255 * (1 - C), G = 255 * (1 - M), B = 255 * (1 - Y).

Let's illustrate this with PHP code:

``````function cmykToRgb(\$c, \$m, \$y, \$k) {
\$c /= 100;
\$m /= 100;
\$y /= 100;
\$k /= 100;

\$r = 255 * (1 - \$c) * (1 - \$k);
\$g = 255 * (1 - \$m) * (1 - \$k);
\$b = 255 * (1 - \$y) * (1 - \$k);

return [\$r, \$g, \$b];
}

list(\$r, \$g, \$b) = cmykToRgb(40, 20, 10, 30);
echo "RGB: (\$r, \$g, \$b)";
``````

### Output:

``RGB: (153, 204, 229)``

## Method 2: Using Color Libraries

Performing manual calculations can be error-prone and time-consuming. To simplify the process, we can leverage color manipulation libraries available in PHP. One such library is the `Imagine` library. It provides a convenient way to work with images and colors, including conversions between different color models.

First, we need to install the library using Composer:

``````composer require imagine/imagine
``````

Here's how we can use the Imagine library to convert CMYK to RGB:

``````use Imagine\Image\Palette\RGB;
use Imagine\Image\Palette\CMYK;

function cmykToRgbUsingLibrary(\$c, \$m, \$y, \$k) {
\$cmykPalette = new CMYK();
\$rgbPalette = new RGB();

\$cmykColor = \$cmykPalette->color([\$c, \$m, \$y, \$k]);
\$rgbColor = \$rgbPalette->color(\$cmykColor->getValue());

return \$rgbColor->getValue();
}

\$rgbColor = cmykToRgbUsingLibrary(40, 20, 10, 30);
echo "RGB: " . implode(', ', \$rgbColor);
``````

### Output:

``RGB: 153, 204, 229``

## Conclusion:

Converting CMYK to RGB is an essential skill when working with colors in various digital and print projects. In this blog, we have discussed two methods for performing this conversion using PHP. The first method involved manual calculations using formulas, while the second method showcased the convenience of using color manipulation libraries like Imagine.