"Generator" is a better name here

app/controllers/asciicasts_controller.rb

@@ -28,7 +28,7 @@ class AsciicastsController < ApplicationController
       end
 
       format.png do
-        image_updater.update(asciicast) if asciicast.image_stale?
+        asciicast_image_generator.generate(asciicast) if asciicast.image_stale?
         redirect_to asciicast.image_url
       end
     end
@@ -84,8 +84,8 @@ class AsciicastsController < ApplicationController
     AsciicastUpdater.new
   end
 
-  def image_updater
-    AsciicastImageUpdater.new(self)
+  def asciicast_image_generator
+    AsciicastImageGenerator.new(self)
   end
 
 end

app/services/asciicast_image_generator.rb

@@ -1,4 +1,4 @@
-class AsciicastImageUpdater
+class AsciicastImageGenerator
   PIXEL_DENSITY = 2
 
   attr_reader :template_renderer, :rasterizer, :image_inspector
@@ -9,7 +9,7 @@ class AsciicastImageUpdater
     @image_inspector = image_inspector
   end
 
-  def update(asciicast)
+  def generate(asciicast)
     Dir.mktmpdir do |dir|
       page_path = "#{dir}/asciicast.html"
       image_path = "#{dir}/#{asciicast.image_filename}"