custom thumbnail sizes draft

set-custom-thumbnail-size/functions.php

@@ -0,0 +1,11 @@
+// Add new image sizes:
+add_image_size( 'thumb-512x384', 512, 384, true );
+add_image_size( 'thumb-640x480', 640, 480, true );
+// Register the sizes:
+add_filter( 'image_size_names_choose', 'my_custom_image_sizes' );
+function my_custom_image_sizes( $sizes ) {
+    return array_merge( $sizes, array(
+        'thumb-512x384' => __( 'Thumbnail 512x384px' ),
+        'thumb-640x480' => __( 'Thumbnail 640x480px' ),
+    ) );
+}