Create an array of an attachment image's data.

wp_get_attachment_image_data.php

<?php
/**
 *  Create an array of an attachment image's data.
 *
 *  @param   int    $id     The id of the attachment image
 *  @return  array  $image  An array of all the image data
 */
function wp_get_attachment_image_data( $id=null ) {
    $image = array();

    // Set $id to the post thumbnail image by default
    if ( ! $id ) {
        global $post;
        $id = get_post_thumbnail_id( $post->ID );
    }

    // Check if metadata exists
    if ( ! empty( $id ) && $meta = get_post( $id ) ) {
        $image['href']        = get_permalink( $meta->ID );
        $image['url']         = $meta->guid;
        $image['title']       = $meta->post_title;
        $image['alt']         = ( $alt = get_post_meta( $meta->ID, '_wp_attachment_image_alt', true ) ) ? $alt : $meta->post_title;
        $image['caption']     = $meta->post_excerpt;
        $image['description'] = $meta->post_content;

        // Get all our images sizes
        if ( $sizes = get_intermediate_image_sizes() ) {
            // Add the full size
            array_unshift( $sizes, 'full' );

            // Add the available image sizes
            foreach ( $sizes as $size ) {
                $src = wp_get_attachment_image_src( $id, $size );
                $image['sizes'][$size]             = $src[0];
                $image['sizes'][$size . '-width']  = $src[1];
                $image['sizes'][$size . '-height'] = $src[2];
            }
        } else {
            $image['sizes'] = null;
        }

        return $image;
    }

    return false;
}