title: Showing img in django admin
body: <p>i was trying to show image in django admin. i try this code </p>
  
  <blockquote>
    <p>admin.py</p>
  </blockquote>
  
  <pre><code>@admin.register(SampleImages)
  class CategoryAdmin(admin.ModelAdmin):
      readonly_fields = ['image_tag']
  </code></pre>
  
  <p>and for <strong>models.py</strong> </p>
  
  <pre><code>class SampleImages(models.Model):
      image = models.ImageField(upload_to='images/tile_images')
  
      def image_tag(self):
          return mark_safe('&lt;img src="{}" width="150" height="150"/&gt;'.format(self.image))
  
      image_tag.short_description = 'Image'
  </code></pre>
  
  <p>but image is not showing, i inspect html and that fine.</p>
  
  <pre><code>&lt;img src="images/tile_images/150x150.gif" width="150" height="150"&gt;
  </code></pre>
  
  <p>in django admin when i click image url it say </p>
  
  <blockquote>
    <p>Sample images with ID "1/change/images/tile_images/150x150.gif"
    doesn't exist. Perhaps it was deleted?</p>
  </blockquote>
  
  <p>And image is present in my <strong>images/tile_images</strong> folder. 
  Anyone can help please?.</p>