<?php 
if ( is_admin() ) {
    function add_post_enctype() {
        echo "<script type='text/javascript'>
                  jQuery(document).ready(function(){
                      jQuery('#post').attr('enctype','multipart/form-data');
                  });
              </script>";
    }
    add_action('admin_head', 'add_post_enctype');
}

$new_meta_boxes =
array(

"start" => array(
"name" => "start",
"type" => "start"),


"image" => array(
"name" => "image",
"std" => "",
"type" => "image",
"title" => "Thumbnail Image"), 
 

"bannerimage" => array(
"name" => "bannerimage",
"std" => "",
"type" => "image",
"title" => "Banner Image"), 


"tagline" => array(
"name" => "tagline",
"std" => "",
"type" => "text",
"title" => "Tagline",
"description" => "Tagline to your post"),


"end" => array(
"name" => "end",
"type" => "end"),
);


function new_meta_boxes() {
global $post, $new_meta_boxes;

foreach($new_meta_boxes as $meta_box) {
$meta_box_value = get_post_meta($post->ID, $meta_box['name'].'', true);

if($meta_box_value == "")
$meta_box_value = $meta_box['std'];

echo'<input type="hidden" name="'.$meta_box['name'].'_noncename" id="'.$meta_box['name'].'_noncename" value="'.wp_create_nonce( plugin_basename(__FILE__) ).'" />';
if($meta_box['type'] == "start") {

echo "<div class='optionsbox'><style type='text/css'>.optionsbox {
display:block;
width:auto;
float:none;
overflow: hidden;
}

.optionsbox input, .optionsbox textarea {
outline:none;
padding:5px;
color:#999;
}

.optionsbox input:focus, .optionsbox textarea:focus {
border-color:#999;
color:#666;
}

.optionsbox p {
margin-bottom:20px;
}

.optionsbox label {
width:140px;
display:block;
float:left;
margin-top:3px;
}

.optionsbox small {
padding-left:140px;
padding-top:3px;
color:#999;
}
</style>";

} else if($meta_box['type'] == "end") { 

	echo '</div>';

} else if($meta_box['type'] == "image") { 

	echo $meta_box['before'];
	
	echo '<div style="background:#f4f4f4;padding:10px;height:120px;margin:0 0 20px 0;display:block">';
	
	if($meta_box_value) { echo '<img style="float:right" src="'.get_bloginfo('template_directory').'/scripts/timthumb.php?src='.$meta_box_value.'&w=120&h=120" alt="" />'; }

	echo'<p><label for="'.$meta_box['name'].'_upload">'.$meta_box['title'].'</label>';
	echo'<input type="file" name="'.$meta_box['name'].'_upload" size="55" /><br />';
	echo'<small>Upload image here</small></p>';
	
	echo'<p><label>&nbsp;</label>';
	echo'<input type="text" name="'.$meta_box['name'].'" value="'.$meta_box_value.'" size="55" /><br />';
	echo'<small>or add a URL to the image here</small></p>';

	echo '</div>';
	
} else if($meta_box['type'] == "text") { 

	echo $meta_box['before'];
	
	echo'<p style="margin-bottom:20px;"><label style="width:140px;display:block;float:left;margin-top:3px;" for="'.$meta_box['name'].'">'.$meta_box['title'].'</label>';
	echo'<input style="color:#666;" type="text" name="'.$meta_box['name'].'" value="'.$meta_box_value.'" size="55" /><br />';
	echo'<small style="padding-left:140px;padding-top:3px;">'.$meta_box['description'].'</small></p>';

} else if($meta_box['type'] == "checkbox") { 

	echo $meta_box['before'];
	
	echo'<p style="margin-bottom:20px;"><label style="width:140px;display:block;float:left;margin-top:3px;" for="'.$meta_box['name'].'">'.$meta_box['title'].'</label>';
	if($meta_box_value) { $checked = "checked=\"checked\""; } else { $checked = ""; }
	echo '<input style="display:block;float:left;width:20px;margin:5px 0 0 0;" '.$checked.' type="checkbox" name="'.$meta_box['name'].'" /><br/>';
	echo'<small style="clear:both;padding-left:140px;padding-top:3px;display:block;">'.$meta_box['description'].'</small></p>';

} else if($meta_box['type'] == "textarea") { 

	echo $meta_box['before'];
	echo'<p style="margin-bottom:20px;"><label style="width:140px;display:block;float:left;margin-top:3px;" for="'.$meta_box['name'].'">'.$meta_box['title'].'</label>';
	echo'<textarea style="color:#666;" name="'.$meta_box['name'].'" cols="50" rows="4">'.stripslashes($meta_box_value).'</textarea><br />';
	echo'<small style="padding-left:140px;padding-top:3px;">'.$meta_box['description'].'</small></p>';

} 

}
}


function create_meta_box() {
global $theme_name;
if ( function_exists('add_meta_box') ) {
add_meta_box( 'new-meta-boxes', 'Post Options', 'new_meta_boxes', 'post', 'normal', 'high' );
add_meta_box( 'new-meta-boxes', 'Page Options', 'new_meta_boxes', 'page', 'normal', 'high' );
}
}


function save_postdata( $post_id ) {
global $post, $new_meta_boxes;
$post_id = wp_is_post_revision($post_id);

foreach($new_meta_boxes as $meta_box) {

	if ( !wp_verify_nonce( $_POST[$meta_box['name'].'_noncename'], plugin_basename(__FILE__) )) {
	return $post_id;
	}

	if ( 'page' == $_POST['post_type'] ) {
	if ( !current_user_can( 'edit_page', $post_id ))
	return $post_id;
	} else {
	if ( !current_user_can( 'edit_post', $post_id ))
	return $post_id;
	}

$imageuploadlocation = "";
$metaboxname = "";
$metaboxname_upload = "";
	
if($meta_box['type'] == 'image') {
	
	$metaboxname = $meta_box['name'];
	$metaboxname_upload = $metaboxname.'_upload';
	
	if($_FILES[$metaboxname_upload]['name'] != "") {
		$overrides = array( 'test_form' => false);
		$imagefile=wp_handle_upload($_FILES[$metaboxname_upload], $overrides);
		$imageuploadlocation = $imagefile['url'];
		delete_post_meta($post_id, $metaboxname, get_post_meta($post_id, $metaboxname, true));
		add_post_meta($post_id, $metaboxname, $imageuploadlocation, true);
	} else {
		$imageuploadlocation = get_post_meta($post_id, $metaboxname, true);
		delete_post_meta($post_id, $metaboxname, get_post_meta($post_id, $metaboxname, true));
		add_post_meta($post_id, $metaboxname, $_POST[$metaboxname], true);
	} 
	

} else {

	$data = $_POST[$meta_box['name'].''];
	if(get_post_meta($post_id, $meta_box['name'].'') == "")
	add_post_meta($post_id, $meta_box['name'].'', $data, true);
	elseif($data != get_post_meta($post_id, $meta_box['name'].'', true))
	update_post_meta($post_id, $meta_box['name'].'', $data);
	elseif($data == "")
	delete_post_meta($post_id, $meta_box['name'].'', get_post_meta($post_id, $meta_box['name'].'', true));

}


}

}



add_action('admin_menu', 'create_meta_box');
add_action('save_post', 'save_postdata', 12);?>

<?php 
$new_meta_boxes =
array(

"start" => array(
"name" => "start",
"type" => "start"),


"image" => array(
"name" => "image",
"std" => "",
"type" => "image",
"title" => "Thumbnail Image"), 
 

"bannerimage" => array(
"name" => "bannerimage",
"std" => "",
"type" => "image",
"title" => "Banner Image"), 


"tagline" => array(
"name" => "tagline",
"std" => "",
"type" => "text",
"title" => "Tagline",
"description" => "Tagline to your post"),


"end" => array(
"name" => "end",
"type" => "end"),
);


function new_meta_boxes() {
global $post, $new_meta_boxes;

foreach($new_meta_boxes as $meta_box) {
$meta_box_value = get_post_meta($post->ID, $meta_box['name'].'', true);

if($meta_box_value == "")
$meta_box_value = $meta_box['std'];

echo'<input type="hidden" name="'.$meta_box['name'].'_noncename" id="'.$meta_box['name'].'_noncename" value="'.wp_create_nonce( plugin_basename(__FILE__) ).'" />';
if($meta_box['type'] == "start") {

echo "<div class='optionsbox'><style type='text/css'>.optionsbox {
display:block;
width:auto;
float:none;
overflow: hidden;
}

.optionsbox input, .optionsbox textarea {
outline:none;
padding:5px;
color:#999;
}

.optionsbox input:focus, .optionsbox textarea:focus {
border-color:#999;
color:#666;
}

.optionsbox p {
margin-bottom:20px;
}

.optionsbox label {
width:140px;
display:block;
float:left;
margin-top:3px;
}

.optionsbox small {
padding-left:140px;
padding-top:3px;
color:#999;
}
</style>";

} else if($meta_box['type'] == "end") { 

	echo '</div>';

} else if($meta_box['type'] == "image") { 

	echo $meta_box['before'];
	
	echo '<div style="background:#f4f4f4;padding:10px;height:120px;margin:0 0 20px 0;display:block">';
	
	if($meta_box_value) { echo '<img style="float:right" src="'.get_bloginfo('template_directory').'/scripts/timthumb.php?src='.$meta_box_value.'&w=120&h=120" alt="" />'; }

	echo'<p><label for="'.$meta_box['name'].'_upload">'.$meta_box['title'].'</label>';
	echo'<input type="file" name="'.$meta_box['name'].'_upload" size="55" /><br />';
	echo'<small>Upload image here</small></p>';
	
	echo'<p><label>&nbsp;</label>';
	echo'<input type="text" name="'.$meta_box['name'].'" value="'.$meta_box_value.'" size="55" /><br />';
	echo'<small>or add a URL to the image here</small></p>';

	echo '</div>';
	
} else if($meta_box['type'] == "text") { 

	echo $meta_box['before'];
	
	echo'<p style="margin-bottom:20px;"><label style="width:140px;display:block;float:left;margin-top:3px;" for="'.$meta_box['name'].'">'.$meta_box['title'].'</label>';
	echo'<input style="color:#666;" type="text" name="'.$meta_box['name'].'" value="'.$meta_box_value.'" size="55" /><br />';
	echo'<small style="padding-left:140px;padding-top:3px;">'.$meta_box['description'].'</small></p>';

} else if($meta_box['type'] == "checkbox") { 

	echo $meta_box['before'];
	
	echo'<p style="margin-bottom:20px;"><label style="width:140px;display:block;float:left;margin-top:3px;" for="'.$meta_box['name'].'">'.$meta_box['title'].'</label>';
	if($meta_box_value) { $checked = "checked=\"checked\""; } else { $checked = ""; }
	echo '<input style="display:block;float:left;width:20px;margin:5px 0 0 0;" '.$checked.' type="checkbox" name="'.$meta_box['name'].'" /><br/>';
	echo'<small style="clear:both;padding-left:140px;padding-top:3px;display:block;">'.$meta_box['description'].'</small></p>';

} else if($meta_box['type'] == "textarea") { 

	echo $meta_box['before'];
	echo'<p style="margin-bottom:20px;"><label style="width:140px;display:block;float:left;margin-top:3px;" for="'.$meta_box['name'].'">'.$meta_box['title'].'</label>';
	echo'<textarea style="color:#666;" name="'.$meta_box['name'].'" cols="50" rows="4">'.stripslashes($meta_box_value).'</textarea><br />';
	echo'<small style="padding-left:140px;padding-top:3px;">'.$meta_box['description'].'</small></p>';

} 

}
}


function create_meta_box() {
global $theme_name;
if ( function_exists('add_meta_box') ) {
add_meta_box( 'new-meta-boxes', 'Post Options', 'new_meta_boxes', 'post', 'normal', 'high' );
add_meta_box( 'new-meta-boxes', 'Page Options', 'new_meta_boxes', 'page', 'normal', 'high' );
}
}


function save_postdata( $post_id ) {
global $post, $new_meta_boxes;
$post_id = wp_is_post_revision($post_id);

foreach($new_meta_boxes as $meta_box) {

	if ( !wp_verify_nonce( $_POST[$meta_box['name'].'_noncename'], plugin_basename(__FILE__) )) {
	return $post_id;
	}

	if ( 'page' == $_POST['post_type'] ) {
	if ( !current_user_can( 'edit_page', $post_id ))
	return $post_id;
	} else {
	if ( !current_user_can( 'edit_post', $post_id ))
	return $post_id;
	}

$imageuploadlocation = "";
$metaboxname = "";
$metaboxname_upload = "";
	
if($meta_box['type'] == 'image') {
	
	$metaboxname = $meta_box['name'];
	$metaboxname_upload = $metaboxname.'_upload';
	
	if($_FILES[$metaboxname_upload]['name'] != "") {
		$overrides = array( 'test_form' => false);
		$imagefile=wp_handle_upload($_FILES[$metaboxname_upload], $overrides);
		$imageuploadlocation = $imagefile['url'];
		delete_post_meta($post_id, $metaboxname, get_post_meta($post_id, $metaboxname, true));
		add_post_meta($post_id, $metaboxname, $imageuploadlocation, true);
	} else {
		$imageuploadlocation = get_post_meta($post_id, $metaboxname, true);
		delete_post_meta($post_id, $metaboxname, get_post_meta($post_id, $metaboxname, true));
		add_post_meta($post_id, $metaboxname, $_POST[$metaboxname], true);
	} 
	

} else {

	$data = $_POST[$meta_box['name'].''];
	if(get_post_meta($post_id, $meta_box['name'].'') == "")
	add_post_meta($post_id, $meta_box['name'].'', $data, true);
	elseif($data != get_post_meta($post_id, $meta_box['name'].'', true))
	update_post_meta($post_id, $meta_box['name'].'', $data);
	elseif($data == "")
	delete_post_meta($post_id, $meta_box['name'].'', get_post_meta($post_id, $meta_box['name'].'', true));

}


}

}



add_action('admin_menu', 'create_meta_box');
add_action('save_post', 'save_postdata', 12);?>

Original custom fields code based on Wefunction's code here: http://wefunction.com/2008/10/tutorial-creating-custom-write-panels-in-wordpress/ enhanced to add support for uploading images.

Custom fields with Upload image option - WordPress

image, wordpress

PHP