Goto admin>System>Configuration>Checkout>Shopping Cart>Configurable Product Image make it Product Thumbnail Itself this make child product image
Instead of sending
$_item->getProductId()
send $_item
and put somelogic
$_item
for configurable product $_Item>getSku give child product a other time give main products. so just child product using item sku
I guess you have used third party extension so i have change some change according my concept change
Step1:instead of send product send all item object
findColorImage($_item->getProductId(),$product_base,'color', 'image');
to
findColorImage($_item,$product_base,'color', 'image');
Step2: some change on function
public function findColorImage($item, $arr, $key, $type)
{
/* $value set here*/
$value=$item->getProductId();
$found = '';
if(isset($arr[$key])) {
$total = count($arr[$key]);
if($total>0)
{
for($i=0; $i<$total;$i++)
{
if($value == ucwords($arr[$key][$i]))//if it matches the color listed in the attribute
{
$found = $arr[$type][$i];//return the image src
}
}
}
}
if ($found == '') {
if (isset($arr['image'])){
$found = $arr['image'][0];
}
}
/* for configurable product send child product image */
if($item->getProductTypeId="configurable"){
$ChildProduct=Mage::getModel('catalog/product')->loadByAttribute('sku',$item->getSku());
$found=Mage::helper('catalog/image')->init($ChildProduct, 'thumbnail');
}
return $found;
}