Convert hexadecimal value to CMYK

• mikemikelle07

• June 24, 2020 at 4:40 am

Hello everyone.

I’m using color picker in a repeater field and I want to convert hexadecimal value to CMYK. I wonder how I can do this. Can you help me?

Thank you.

• John Huebner

• June 25, 2020 at 2:43 am

https://stackoverflow.com/questions/3333585/php-hex-to-cmyk

• mikemikelle07

• June 25, 2020 at 3:58 am

Thank you @John!

I have found this piece of code, but I wonder how can I adjust the ‘sub_field’ in my code.

• John Huebner

• June 25, 2020 at 4:09 am

You can’t. You add the code to your site and then use it with the result from the field.

echo rgb2cmyk(hex2rgb(get_sub_field('your-field-name')));

• mikemikelle07

• June 25, 2020 at 4:31 am

in function.php :

function hex2rgb($hex) {
	$color = str_replace('#','',$hex);
	$rgb = array(
	   'r' => hexdec(substr($color,0,2)),
	   'g' => hexdec(substr($color,2,2)),
	   'b' => hexdec(substr($color,4,2)),
	);
	return $rgb;
 }
 
 function rgb2cmyk($var1,$g=0,$b=0) {
	if (is_array($var1)) {
	   $r = $var1['r'];
	   $g = $var1['g'];
	   $b = $var1['b'];
	} else {
	   $r = $var1;
	}
	$cyan = 255 - $r;
	$magenta = 255 - $g;
	$yellow = 255 - $b;
	$black = min($cyan, $magenta, $yellow);
	$cyan = @(($cyan    - $black) / (255 - $black));
	$magenta = @(($magenta - $black) / (255 - $black));
	$yellow = @(($yellow  - $black) / (255 - $black));
	return array(
	   'c' => $cyan,
	   'm' => $magenta,
	   'y' => $yellow,
	   'k' => $black,
	);
 }
 
 echo rgb2cmyk(hex2rgb(get_sub_field('color_hex')));

page template :

<span class="cmyk"><?php rgb2cmyk('color_hex', $post->ID);?></span>

And I have some errors: Array to string conversion. What I am doing wrong?

• John Huebner

• June 25, 2020 at 5:02 am

Yes, that function returns a array, sorry, that depends on what you want to do with the values returned.

• mikemikelle07

• June 25, 2020 at 5:04 am

Basically when I choose a hex color from the color picker, I want to return this converted value in CMYK format 🙂

• John Huebner

• June 25, 2020 at 5:12 am

$cmyk = rgb2cmyk(hex2rgb(get_sub_field('your-field-name')));
foreach ($cmyk as $i => $v) {
  echo $i,'=',$v,'<br />';
}

• mikemikelle07

• June 25, 2020 at 5:20 am

As an example the value: #060e5b returns me

c=0.93406593406593
m=0.84615384615385
y=0
k=164

But I want to return : cmyk(93,85,0,64) Any idea? 🙂

Regards

• John Huebner

• June 25, 2020 at 6:03 am

Information on what you want to output is what I was trying to get you to tell me.

$cmyk = rgb2cmyk(hex2rgb(get_sub_field('your-field-name')));
foreach ($cmyk as $i => $v) {
  echo 'cmyk('.implode(',', $cmyk).')';
}

• mikemikelle07

• June 25, 2020 at 7:19 pm

@John thank you for your help. In my case, I don’t think that I need the foreach ($cmyk as $i => $v), because returns the value a lot of times and I want this value, only one time. 🙂