http://www.ramonfincken.com/permalink/topic211.html

1)
Install Custom Field Template ( wp-admin > plugins > add new )

2)
Config Custom Field Template like this ( Leave the rest as it is )

Template #0
* Template Title:
Header image

* Post type:
Both

* Template Content:
[File Upload]
type = file


3)
Make sure that in Atahualpa > Configure Header Area this is entered:
%image

4)
Now for 2 copy and paste actions in the code, use notepad/gedit/araneae whatever text editor you want.

OPEN
wp-content/themes/atahualpa/functions/bfa_header_config.php

DIY
Now make a backup of this file!

FIND
# Around line 274
// Header Image
if ( strpos($header_items,'%image') !== FALSE ) {

FIND
ob_start();


AFTER, ADD

// Ramon Fincken, http://www.ramonfincken.com/permalink/topic211.html
	global $wpdb; // We need a DB object/connection

	$temp = get_post_meta($post->ID, 'File Upload', true);
	$sql = "SELECT meta_value FROM $wpdb->postmeta WHERE post_id = '".$temp."' AND meta_key = '_wp_attached_file'";

	$temp = $wpdb->get_results($sql, ARRAY_N);
	if(count($temp) == 1) // If we find an image
	{
		$temp_image = $temp[0][0];
		$single_uploadpath = get_option('home').'/wp-content/uploads/';
		if(!file_exists($single_uploadpath.$temp_image)) // Make sure it _really_ exists on the server
		{
			// if this is WordPress MU .. do not keep your nickers in a twist .. 
			$upload_path1 = ABSPATH . get_option('upload_path');
			$upload_path2 = str_replace('themes/' . get_option('stylesheet').'/functions', '', $_SERVER['DOCUMENT_ROOT']).'/wp-content/blogs.dir/' . $wpdb->blogid . '/files';			
			if(file_exists($upload_path1.$temp_image))
			{
				$temp_image = $upload_path1.$temp_image;
			}
			elseif(file_exists($upload_path2.$temp_image))
			{
				$temp_image = $upload_path2.$temp_image;
			}
			else
			{
				$upload_path1 .= '/';
				$upload_path2 .= '/';
				if(file_exists($upload_path1.$temp_image))
				{
					$temp_image = $upload_path1.$temp_image;
				}
				elseif(file_exists($upload_path2.$temp_image))
				{
					$temp_image = $upload_path2.$temp_image;
				}
				else
				{
					// Not found at all ..
					unset($temp_image);
				}
			}
			if(isset($temp_image))
			{
				// From serverpath to realpath
				$temp = explode('/wp-content',$temp_image);
				$temp_image = 'http://'.$_SERVER[HTTP_HOST].'/wp-content'.$temp[1];
			}
		}
		else
		{
			$temp_image = $single_uploadpath.$temp_image;
		}
	}
	// Ramon Fincken, http://www.ramonfincken.com/permalink/topic211.html


PARTIAL FIND
echo '<div id="imagecontainer" class="header-image-container" style="background: url(' .

BEFORE, ADD
	// Ramon Fincken, http://www.ramonfincken.com/permalink/topic211.html
	if(!isset($temp_image))
	{


PARTIAL FIND
$bfa_header_images[array_rand($bfa_header_images)] . ') ' . $bfa_ata['headerimage_alignment'] . ' no-repeat;">';

AFTER, ADD
}

	// File exists
	if(isset($temp_image))
	{
		$header_image = '<div id="imagecontainer" class="header-image-container" style="background: url(';
		$header_image .= $temp_image; // GOGOGO !
		$header_image .= ') ' . $bfa_ata['headerimage_alignment'] . ' no-repeat;">';	
		echo $header_image;
	}
	// Ramon Fincken, http://www.ramonfincken.com/permalink/topic211.html




5)
Now go to a page or post and upload a new header image for that page !

You can always remove the image again and the default header image will be shown!