sqcdy_acf_rgb.php

<?php
/*
Plugin Name: Square Candy ACF RGB color output
Plugin URI: http://squarecandydesign.com
Description: provides a function to output RGB values from ACF colorpicker fields
Author: Peter Wise
Version: 0.1
Author URI: http://squarecandydesign.com
*/

/*

Example Usage:

h1 { color: rgb(<?php sqcdy_acf_rgb('my_colorpicker_field'); ?>); }

<?php $rgb = sqcdy_get_acf_rgb('my_colorpicker_option_field', 'option'); ?>
h2 { color: rgb(<?php echo $rgb ?>); }

div { background-color: rgba(<?php sqcdy_acf_rgb('my_colorpicker_field'); ?>,0.5); }

<?php echo 'h3 {color: rgba(' . sqcdy_get_acf_rgb('my_colorpicker_field') . ',0.5); }'; ?>

*/


// output an acf colorpicker field as R,G,B
function sqcdy_get_acf_rgb($field, $id) {
	if ( function_exists('get_field') ) {
		$hex = get_field($field, $id);
		// extra sanity check that we're dealing with the hex colors
		// in #NNNNNN format that ACF/WordPress/Iris colorpicker returns
		if (strlen($hex) == 7 && substr($hex,0,1) == '#') {
			$r = hexdec(substr($hex,1,2));
			$g = hexdec(substr($hex,3,2));
			$b = hexdec(substr($hex,5,2));
			return $r . ',' . $g . ',' . $b;
		}
		else {
			// provide a default in an emergency
			return "128,128,128" ;
		}
	}
}

function sqcdy_acf_rgb($field, $id) {
	echo sqcdy_get_acf_rgb($field, $id);
}

Nevermind - I see where the issue would come up from you code now. Maybe try keeping the conversion function separate from the ACF stuff like this:

function sqcdy_get_acf_rgb($hex) {
	// sanity check that we're dealing with the hex colors
	// in #NNNNNN format that ACF/WordPress/Iris colorpicker returns
	if (strlen($hex) == 7 && substr($hex,0,1) == '#') {
		$r = hexdec(substr($hex,1,2));
		$g = hexdec(substr($hex,3,2));
		$b = hexdec(substr($hex,5,2));
		return $r . ',' . $g . ',' . $b;
	}
	else {
		// provide a default in an emergency
		return "128,128,128" ;
	}
}

Then in your theme:

$myrepeater = get_field('my_repeater');
foreach ($myrepeater as $item) {
    $hex = $item['color_subfield'];
    $rgb = sqcdy_get_acf_rgb($hex);
    // do stuff with $rgb
}