Restrict wp media modal image sizes upload

restrict-wp-image-size.php

<?php 
function wp_handle_upload_prefilter( $file ){
    $tempImg = getimagesize( $file['tmp_name'] );
    $width= $img[0];
    $height =$img[1];
    // lets restrict image size (width*height) 400*640 minimum
    if ( $minimum['width'] < 400 )
        return array( "error" => "Image dimensions are too small. Minimum width is 400px. Uploaded image width is 400 px" );
    elseif ( $minimum['height'] < 640 )
        return array( "error" => "Image dimensions are too small. Minimum height is 640px. Uploaded image height is 640 px" );
    else
        return $file; 
}
add_filter( 'wp_handle_upload_prefilter', 'wp_handle_upload_prefilter' );