BlogPostScrubber.rb

class BlogPostScrubber < Rails::Html::PermitScrubber
  def allowed_node?(node)
    %w(div p video strong em a blockquote h3 h4 h5 h6 br hr i label li span u ul ol).include?(node.name)
  end

  def skip_node?(node)
    node.text?
  end

  def scrub_attribute?(name)
    name == "style"
  end
end

dump.rb

#body data
@blog_post.body = "<p>Hello <strong>bruce</strong>,</p>\r\n\r\n<p><img alt=\"\" src=\"https://upload.wikimedia.org/wikipedia/commons/b/b6/1896_Olympic_opening_ceremony.jpg\" style=\"height:150px; width:192px\" /></p>\r\n"

out.html

<p>Hello <strong>bruce</strong>,</p>

<p><img src="https://upload.wikimedia.org/wikipedia/commons/b/b6/1896_Olympic_opening_ceremony.jpg" style="height: 150px; width: 192px;"></p>

show.html.erb

#view code
<p id="notice"><%= notice %></p>

<p>
  <strong>Title:</strong>
  <%= @blog_post.title %>
</p>

<p>
  <strong>Body:</strong>
  <div id="mydiv">
  <%= sanitize @blog_post.body, scrubber: BlogPostScrubber.new %>
</div>
</p>

<%= link_to 'Edit', edit_blog_post_path(@blog_post) %> |
<%= link_to 'Back', blog_posts_path %>