AMP Extract Image without external request

amp-media-size.php

<?php
add_filter( 'amp_extract_image_dimensions_batch', function ( $dimensions ) {
	$home_url = get_home_url();
	foreach ( $dimensions as $url => &$data ) {
		if ( false !== strpos( $url, $home_url ) ) {
			$attachment_id = wpcom_vip_attachment_url_to_postid( $url );
			if ( false !== $attachment_id ) {
				$src    = wp_get_attachment_image_src( $attachment_id );
				$height = $src[1];
				$width  = $src[2];
				if ( ! empty( $height ) && ! empty( $width ) ) {
					$data = [
						'width'  => $width,
						'height' => $height,
					];
				}
			}
		}
	}
	return $dimensions;
} );

add_action( 'amp_extract_image_dimensions_batch_callbacks_registered', function () {
	$callback = [
		'AMP_Image_Dimension_Extractor',
		'extract_by_downloading_images',
	];
	if ( has_filter( 'amp_extract_image_dimensions_batch', $callback ) ) {
		remove_filter( 'amp_extract_image_dimensions_batch', $callback, 999 );
	}
} );

See ampproject/amp-wp@3e6f1ac

Also see this might cause issue with large DB: ampproject/amp-wp#651 (This gist is adding query back which was removed).