Using Amazon product images on your website

Dan Sosedoff — Tue, 15 Jun 2010 06:20:17 +0000

Amazon has an awesome image service. You can use their product images on your site, adjusting them for you needs. All you have to know – one image url of your product. Having that string will provide you an access to its dynamic image scaling service which i had to use recently.

So, lets say you have books on your website, but you dont have any good images for them. There is 2 ways to solve your problem: 1) download it from whatever place and resize 2) use amazon!

Here goes small overview.

Unfortunately, i didnt have any time to play with image service for different countries, but i assume that wont change that much. Lets take a look on a regular image:

http://ecx.images-amazon.com/images/I/41ygBmdaIfL._SL500_SS100_.jpg

It has different parts:
1) URL base: http://ecx.images-amazon.com/images/I/
2) Image code: 41ygBmdaIfL
3) Size format (surrounded by underscores): _SL500_SS100_
4) Format: jpg/gif/png

Some words about image format. It can vary from square thumbnails to images with specific max width and height. For example: _SX100_ will produce image that 100 pixels wide, height will be calculated proportionally. SH100 will give opposite result, scaled by 100 pixels maximum height, SS100 – 100×100 pixels thumbnail. And so on, you can find other similar crop codes while exploring amazon store on different pages, all you need is to take a look on image sources.

Now, we need to use this with Ruby:

require 'net/http'
 
module Amazon
  # parse amazon image url and get image code and extension
  def self.parse_image(url)
    result = url.scan(/^http:\/\/ecx.images-amazon.com\/images\/I\/([a-z0-9\-\%]{1,})(.*)_.(jpg|jpeg|gif)/i)
    unless result.nil?
      unless result[0].nil?
        match = result.first
        return {:code => match.first.to_s, :extension => match.last.to_s}
      end
    end
  end
 
  # make a new amazon image url based on code and size
  def self.make_image(image, size)
    "http://ecx.images-amazon.com/images/I/#{image[:code]}._#{size.upcase}.#{image[:extension]}"
  end
 
  # check if actual image exists
  def self.check_image(url)
    begin
      uri = URI.parse(url)
      req = Net::HTTP::Get.new(uri.path)
      res = Net::HTTP.start(uri.host, uri.port) { |http| http.request(req) }
      return res.code == '200' && res.content_length.to_i > 0
    rescue Exception
      false
    end
  end
end

And usage:

url = 'http://ecx.images-amazon.com/images/I/51O65dIoZCL._SX117_.jpg'
info = Amazon.parse_image(url)
unless info.nil?
  new_url = Amazon.make_image(info, 'sx100')
  if Amazon.check_image(new_url)
    puts "Cool! Resized image: #{new_url}"
  else
    puts "Sorry, this image does not exist!"
  end
else
  puts "Cant identify image!"
end

Some notes about the process. The only reason why method “check_image” uses GET method instead of HEAD is because if image cannot be generated or not found in amazon`s cache the response is still valid sometimes. I`ve checked it on 50k images and sometimes HEAD request indicates that response is valid while it not supposed to. Otherwise i would use HEAD.

Scaling images with RMagick

Dan Sosedoff — Sat, 14 Mar 2009 07:37:03 +0000

Simple class that providing scaling (rectangle and thumbnails) for images using RMagick and Ruby.
Code:

class ImageScale
    def change_geometry(sz,value)
        w = sz[0] ; h = sz[1]
            if w > h
                sz[0] = value
                sz[1] = ((value * h) / w).floor
            else
                sz[1] = value
                sz[0] = ((value * w) / h).floor
            end
            return sz
    end
 
    def make_rect(file_in,file_out, width, quality=85, sharp=false) 
        if FileTest.exists?(file_in)
            begin
                img = Magick::Image.read(file_in).first
                img.crop_resized!(width,width, Magick::CenterGravity)
                img = img.sharpen(0.5, 0.5) if sharp
                img.write(file_out) { self.quality = quality }
                return true if FileTest.exists?(file_out)
            rescue Magick::ImageMagickError
                return false
            end
        end
        return false
    end
 
    def make_thumb(file_in,file_out, width_to, quality=85, sharp=false) 
        if FileTest.exists?(file_in)
            begin
                img = Magick::Image.read(file_in).first
                info = [img.columns,img.rows]
                sz = change_geometry(info, width_to)
                img = img.resize(sz[0],sz[1])
                img = img.sharpen(0.5, 0.5) if sharp
                img.write(file_out) { self.quality = quality }
                return true if FileTest.exists?(file_out)
            rescue Magick::ImageMagickError
                return false
            end
        end
        return false
    end
end

Ok, let`s see how this class working. For example, we have source image:

Function ImageScale.make_rect(src,dest,64) will produce such image:

Function ImageScale.make_thumb(src,dest,200) will produce thumbnail:

There is optional parameter sharp to use sharping. Optional parameter quality is set to 85% compression value.

dan.thoughts » images

Using Amazon product images on your website

Scaling images with RMagick