I am trying to create an app that allows a user to create a text treatment (either by uploading a graphic or in a WYSIWYG editor), and upload it -- the app would then render the uploaded text treatment and show that, overlaid on the side of a building (for a mockup of what it would look like if it were on a billboard, building, or what-not)
I am developing the app in Ruby on Rails, and I know some image-processing libraries like RMagick, allows you to manipulate uploaded imagery in special ways, but I wanted to see if anybody had any other advice on the best way to implement this.
Sorry for the vagueness, and thank you for your time!
I do this for one of my clients. RMagick is a fine choice. I personally prefer GraphicsMagick, which is not quite as popular yet is better written (IMHO).
Consider using alpha channel transparency, which makes overlays especially easy. For example, use PNGs with transparent channels.
Related
I am using paperclip to upload images in my rails application
Gem: https://github.com/thoughtbot/paperclip
Now I want to check the quality of image
For exa: image is blurred or not, image qaulity is low or image clicked while covering the camera lence
Is this possible in rails?
Thanks in advance
Everything is possible in Ruby. Rails is just a web framework.
If you are asking if Ruby or Rails or paperclip have something like
Image.first.blurred?
then unfortunately not. I would guess that no programming language or framework has this specific functionality build in.
But since we are software developers we can utilize tons of library's so our app is obeying to everything that we want to achieve. But first we have to teach them.
OpenCV would be a nice library for such functionality. Its used in tons of usecases when visual analyses is required. There is also a wrapper in ruby for it.
Sure for your use case you have to to build some small library for it. Here you have an example in python which sure be easily translated to ruby. When you got this working you even could implement some Model extension to enable
SomeObject.blurred?
I am trying to make an application which make a editable document file(doc or pdf) from an image. I am planning to use tesseract for extraction of the text. But i am not yet sure how to get the basic formatting of the text(size,bold,italic,underline) & images that might be present in the document image. I am planning to use J2EE, to make a Web Based App(Have to use J2EE). I think i might be able to recognize the components and formatting of the document using OpenCV, but i am not really sure.
Given that you are planning to use Tesseract for the basic OCR capabilities, try looking into the hORC formatted output. That includes quite a lot of additional information about font-size, font-face, position, etc.
You can find a description of hOCR here:
https://docs.google.com/document/d/1QQnIQtvdAC_8n92-LhwPcjtAUFwBlzE8EWnKAxlgVf0/preview#heading=h.e903b9bca924
If that doesn't work out, it depends on how much effort you want to put into Tesseract. It's internal APIs (available in Java via Tess4J, among others) do provide much of the information that you would need to reconstruct the page layout.
I am interested in building a Rails based system for handling the display and organization of large amounts of photos. This is sort of like Flickr but smaller. Each photo will have metadata associated with it. Photos will be shown in a selectable list and grid view. It would be nice to be able to load images as they are needed as well (as this would probably speed things up).
At the moment I have a test version of my database working by images loading from the assets/images directory but it is beginning to run slow when displaying several images (200-600 images). This is due to the way I have my view setup. I am using a straight loop to display the images in both list and grid layouts.
I also manually resized the thumbnails and a medium sized image from a full sized source image. I am investigating other resizing methods. Any advice is appreciated here as well.
As I am new to handling the images this way, could someone point me in a direction based on experience designing and implementing something like Flickr?
I am investigating the following tools:
Paperclip
http://railscasts.com/episodes/134-paperclip
Requirements: ImageMajick
attachment_fu
http://clarkware.com/blog/2007/02/24/file-upload-fu#FileUploadFu
Requirement: One of the following: ImageScience, RMagick, miniMagick, ImageMajick?
CarrierWave
http://cloudinary.com/blog/ruby_on_rails_image_uploads_with_carrierwave_and_cloudinary
http://cloudinary.com/blog/advanced_image_transformations_in_the_cloud_with_carrierwave_cloudinary
I'd go with Carrierwave anyday. It is very flexible and has lot of useful strategies. It generates it's on Uploader class and has all nifty and self explanatory features such as automatic generation of thumbnails (as specified by you), blacklisting, formatting image, size constraints etc; which you can put to your use.
This Railscast by Ryan Bates - http://railscasts.com/episodes/253-carrierwave-file-uploads is very useful, if you haven't seen it already.
Paperclip and CarrierWave are totally appropriate tools for the job, and the one you choose is going to be a matter of personal preference. They both have tons of users and active, ongoing development. The difference is whether you'd prefer to define your file upload rules in a separate class (CarrierWave), or if you'd rather define them inline in your model (Paperclip).
I prefer CarrierWave, but based on usage it's clear plenty of people feel otherwise.
Note that neither gem is going to do anything for your slow view with 200-600 images. These gems are just for handling image uploads, and don't help you with anything beyond that.
Note also that Rails is really pretty bad at handling file uploads and file downloads, and you should avoid this where possible by letting other services (a cdn, your web server, s3, etc) handle these for you. The central gotcha is that if you handle a file transfer with rails, your entire web application process is busy for the duration of the transfer. (For related discussion on this topic, see: Best Ruby on Rails Architecture for Image Heavy App).
I have a site where a user can upload a photo. I have no idea how to handle photos. To make a thumbnail out of a large res photo, do I just resize the width and the height? Or is there a better way to do this?
If you could point me to any resources or give me any tips, that would be great.
I'm using Ruby on Rails, if that matters. I don't really want gems for this because I want to learn how to do it myself.
For some of this, "learning how to do it yourself" is going to be a significant undertaking. Resizing the image, for example. Go ahead and find an open source library (such as a gem) that resizes images and look through its source code. It's not impossible to do on your own, but a lot of that sort of thing is built on the expertise that's come before, etc. There's nothing wrong with making use of a tool somebody else has created, provided that you understand what the tool is doing.
A few points to hopefully help you out:
Go with a white-list approach of which image formats you support. Don't just let users upload anything that they call an image.
Each format you support is going to have its own standards (possibly multiple) for meta-data. Stripping out that data wholesale may or may not be a good idea. For example, a jpeg may contain its orientation in its EXIF data and if you strip that out you may be effectively rotating the image. Certain fields, such as geotagging, you may want to strip out in the effort to protect your users' privacy, etc. Again, look into existing libraries for this and see how they do it.
DO NOT implicitly trust the file name extension for determining the type of the image. It's possible for a user to construct a malicious file that isn't really an image, pass it off as an image to an unsuspecting host, and effectively open a security flaw on that host as it tries to process the file as an image. There was a question about determining file type in Ruby here, and I'm sure there's a lot more to be found on the subject.
David answered the question well, but I thought I might be able to provide some more specific information regarding your question.
Use the Paperclip gem, combined with RMagick, an ImageMagick wrapper for Ruby. You can set post-processing options and create multiple resizings.
If you really want to do it yourself, checkout the actual gem at https://github.com/thoughtbot/paperclip and you'll see how that author does it. Part of the thought behind Ruby on Rails is DRTW (Don't Reinvent the Wheel). Utilize what's out there and build on it. It will save you time, and enable you to do more in the longrun.
An alternative is to use a third party service such as http://resizer.co (I am not affiliated)
Replace a URL to an image from your site, say:
http://example.com/images/abc123.jpg
with the following (for a 200 x 200 image)
http://www.resizer.co?image=http://example.com/images/abc123.jpg&w=200&h=200
You may run into issues with distortion and the 'aspect ratio' not being maintained, but it could be a good start.
I'm currently learning rails by creating a simple project management app. I've gotten to the point where I would like to be allow a user upload multiple files - pdfs, docs, xls etc. The user only needs to be able to attach one file at a time, but the possibilty to have multiple documents associated with a project is a must.
I've spent quite a lot of time researching my options, and it appears the two main plugins are attachment_fu and paperclip. From what I've read though, these appear to concentrate specifically on the upload and subsequent resizing of images, something I couldn't care less about. Is there a simpler way to achieve what I'm trying?
Thank you all in advance.
You might still consider using attachment_fu or paperclip as those are the "standard" libraries for such tasks. And they work fine for any kind of file.
The multi-upload can't be made without JS or Flash now. You need add some hack in your view to manage it.