title: Fastest way to check if an image contain any (semi)transparent pixels?
body: <p>Does anyone know is there a better way to check if some image contain a (semi)transparent pixel beside going trough all pixels and check their alpha channel?</p>
  
  <pre><code>[pseudo]
      for each pixel in image:
          if pixel.alpha != 0xff:
              return true
  </code></pre>
  
  <p>Thanks in advance.</p>