This script is a proof of concept (tested), it is not a plugin and is meant to be hacked with,  it assumes a few things:

1. It uses `wp_insert_post` which is quite dangerous and it's advised you do not hook it into any admin hooks, so just run it once!
2. The images must be in the `wp-content\uploads` folder, changing this would require more hoops to jump through. The example uses a custom folder called `\images` in the uploads folder, you can change this part.
3. It does not do any error checking and I wrote it fast, I also only tested it on a folder with 20 images, so results might vary:)

The code below will iterate through the `wp-content\uploads\images` folder and create a post title based on the name of the image being attached to it. You probably want to change this to something better or possible enter meta data using other data you have (Exif maybe).

    function WPSE_1595_image_post() {
    
     	// We need to use the default uploads dir
    	$wp_upload_dir =  wp_upload_dir();
        // The actual folder
    	$wp_upload_images = $wp_upload_dir['basedir'] . '/images';
    	
      	require_once(ABSPATH . 'wp-admin/includes/image.php');
    
     	foreach (new DirectoryIterator($wp_upload_images) as $fileInfo) {
    
    	    if($fileInfo->isDot()) continue;
    	    
    	    $image_base = $fileInfo->getFilename();
    		$image_name = pathinfo($fileInfo, PATHINFO_FILENAME);
    
            //Customize this post data as you wish
    	    $my_post_data = array(
    	                'post_title' => $image_name,
    	                'post_type' => 'post',
    	                'post_category' => array('1'),
    	                'post_author'   => 1,
    	                'post_status' => 'publish'
    	    );
    
    	    wp_insert_post( $my_post_data);
            // We need the ID for the attachment
    	    $post_id = wp_insert_post($my_post_data);
    
    	    $wp_filetype = wp_check_filetype($image_base, null );
      
             //Customize this attachment data as you wish
    	    $attachment = array(
    		     'guid' => $wp_upload_dir['url'] . '/' . $image_name, 
    		     'post_mime_type' => $wp_filetype['type'],
    		     'post_title' => 'child' . $image_name,
    		     'post_content' => '',
    		     'post_status' => 'inherit'
     		);
    
    	    $imagefile = $wp_upload_images . '/' . $image_base;
    	    $attach_id = wp_insert_attachment( $attachment, $imagefile, $post_id );
       	    $attach_data = wp_generate_attachment_metadata( $attach_id, $imagefile );
    
     	    wp_update_attachment_metadata( $attach_id, $attach_data );
     	}	
    }


You would probably have an easier time using:

 - https://codex.wordpress.org/XML-RPC_WordPress_API
 - https://make.wordpress.org/core/tag/migration-portability/ if it
   comes out
 - A direct DB script