20151015030238_create_articles.rb

class CreateArticles < ActiveRecord::Migration
  def change
    create_table :articles do |t|
      t.string :title, null: false
      t.text :content, null: false
      t.binary :image
      t.timestamps null: false
    end
  end
end

article.rb

class Article < ActiveRecord::Base
end

articles_controller.rb

class ArticlesController < ApplicationController
  def show
    @article = Article.find(params[:id])
  end
end

images_controller.rb

class ImagesController < ApplicationController
  def show
    article = Article.find(params[:id])
    send_data article.image, type: 'image/png', disposition: 'inline'
  end
end

routes.rb

Rails.application.routes.draw do
  resources :images, only: :show
  resources :articles, only: :show
end

show.html.erb

<h1><%= @article.title %></h1>
<p>
<%= @article.content %>
<%= image_tag '/images/1' %>
</p>