Image cropping and uploading to Amazon S3 using Ruby on Rails

Cropping Image

The image cropping and uploading is essential part of any web application now days. Recently, I was working on a web application built on ROR platform. Initially we were using attachment_fu gem for image uploading but later there were requirements of cropping the image. I looked for the option for cropping in the attachment_fu but couldn’t found any option for image cropping in it. Finally after go through documentation for attachment_fu and googling for alternative, I found a gem called ‘Paperclip’. Paperclip gem is used for image upload and cropping but no straight forward integration with attachment_fu. So, I come up with idea of integrating attachment_fu with image cropping feature and shall explain step to step implementation of image cropping using attachment_fu.

Image Crop:

There are many javascripts from hotscripts which can be used for image cropping and I have used one of the javasript “Javascript Image Cropper UI” .

Image Processing

The above javascript shall give us the dimensions for the cropped image and we need to process the image using gem ‘RMagick’

=start rdoc
This method takes crop image dimensions along with the original image path
and re-sized the image to the desired size
x: left most x coordinate of image for cropped image from JavaScript
y: left most y coordinate of image for cropped image from JavaScript
Width: width of image for cropped image from JavaScript
Height: height of image for cropped image from JavaScript
Path: Image path from JavaScript

def self.update_attributes_crop(x,y,width,height,path)

    # Get the path of the Directory where Image should be stored
    path = File.dirname(__FILE__) + "/../../public/#{path}"

    orig_img =

    scale = orig_img.crop(x.to_i,y.to_i,width.to_i,height.to_i, true)

    crop_img =,height.to_i)

    orig_img = crop_img.composite(scale,0,0,Magick::OverCompositeOp)



Upload image to Amazon S3
If you want to upload the image to Amazon S3 then you can use :
S3_copy(source, destination, bucket) line of code in your controller

=start rdoc
This method upload the file from local drive to Amazon S3 bucket
Source: source(path) of image from rails server
Destination: destination (relative path) of Image on S3 server
Bucket: your S3 bucket name for image upload
def S3_copy(source, destination, bucket)


	:access_key_id => S3_access_key_id,

	:secret_access_key => S3_secret_access_key


	AWS::S3::S3Object.copy(source,destination,bucket,:access => :public_read)

	policy = AWS::S3::S3Object.acl(destination,bucket)
	policy.grants << AWS::S3::ACL::Grant.grant(:public_read)
	policy.grants << AWS::S3::ACL::Grant.grant(:public_read_acp)


		AWS::S3::S3Object.acl(destination, bucket, policy)


		p 'Issue occurred while granting access for the file'



I hope using above approach you can do image cropping and uploading. Please let me know if you have any questions

Image cropping and uploading to Amazon S3 using Ruby on Rails was last modified: November 14th, 2010 by Pragmaapps