I am planning to explore on QR code generation . I saw the google api http://chart.apis.google.com/chart?cht=qr&chs=75x75&chl=test and its pretty impressive. But it works only for URL's and small data's. So i am thinking about writing a .net app to generate the QR code. So any information on libraries to start with ,will be helpful.
Thanks,
It does not just work for URLs. You can put whatever text you want as an argument (just URL-encode it correctly). It also works for any data size that QR codes can support.
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I am working on a Xamarin QRCode scanner prototype and the aim is to make the App being able to scan QR codes as small as 1.8/1.8 mm. I have tried the GoogleVision and also the ZXing. The GoogleVision is able to scan them but it is not convenient at all since it hardly depends on the Camera quality, position, illumination, and stability. Also tried Camera / Image Scannig to take a picture while the user is able to zoom on the QR code, still so hard to do that for a user (it cannot detect the QR code 9 out of 10).
TBH, I have searched a lot and manipulated these libraries and couldn't get it to work. On the other hand, there are Apps on the market that they can simply scan these small QR codes. (which I believe they are not based on Xamarin) I have noticed some of them are using ZXing but I couldn't find any useful information on how they are managing these small QR Codes! So my question is:
Is it possible to use Xamarin and ZXing or GoogleVision for this matter? If yes, any further information would be hugely appreciated.
Is there any library that can handle these small QR codes (Commercial or non-commercial)?
Thank you in advance.
Cheers 🤘
I am using Google Charts API to generate QR code as referred in this link https://www.gregorystrike.com/2011/01/26/how-to-use-google-charts-api-to-generate-your-own-qr-code/
In this as the parameters are visible it seems to be insecure
Users can change the values available in the parameters using developer tools like inspector element of Firefox. Is there a secure way to generate QR codes
Thanks
QR codes are insecure anyway, anyone can see the data you place in it, by using any reader.
If want to use QR Codes in any sort of secure sense or to store sensitive data you will have to manage encryption and decryption of that data yourself, there a few encrypted examples but its not a heavily used function. Now we are past the Fab stage of QR Codes, they mainly used like barcodes for identification, with the ability to store more information if needed and the odd URL embedded link.
Although the limit is quite large this is still a limit to the amount of data you can place in a QR Code.
Lots of information on the Wikipedia page https://en.wikipedia.org/wiki/QR_code
Assume I have sensitive information (passwords, private keys,...) that I saved to a file which I encrypted.
Is there an easy to use tool to convert back and forth between a small file (say 0.5kB) and an image (QR code?) that I can print out to have a safe backup?
You can use LaTeX with the ps-tricks and pst-barcode modules, it produces nice QR codes, and yesm we used it exactly for this purpose: Paper backup of SSH private keys.
Denso Wave of QR code developer distributes software on their site.
Membership registration on the site is required to obtain it.
Even if you can not print with this, there are various tools regardless of free/commercial, so please search.
The maximum amount of data that can be stored in the QR code is 2953 bytes in binary mode.
However, it depends on the ability of the scanner to use.
QR code FAQ #6 Can an image or sound be stored in a QR Code?
I wrote a linux program to do this, called qr-backup.
In researching similar programs as part of it, I discovered a number of alternative projects as well. All of these are also linux-only.
asc2qr.sh
paperbackup. Focused on GPG/SSH key backup. See also the paperkey preprocessor, to reduce the size of keys.
qrdump (incomplete)
qrpdf
If your file is very small (0.5KB is a good cutoff), you can generate one single QR code. An example command-line program to generate it is qrencode. Several web converters are also available.
I have an Android QR code reading app that runs on a cheap phone with no autofocus. QR code that I must read is small and on camera preview looks blurry. The one app able to read this code is NeoReader.
Does everybody know good free libraries to read QR codes?
I know that:
ZBar (it's ok but not works with blurry code)
ZXing (this Barcode reader not reads the required code; don't tried to integrate)
NeoReader SDK (not free)
My init code for ZBar:
scanner = new ImageScanner();
scanner.setConfig(0, Config.ENABLE, 0);
scanner.setConfig(Symbol.QRCODE, Config.ENABLE, 1);
scanner.setConfig(0, Config.X_DENSITY, 1);
scanner.setConfig(0, Config.Y_DENSITY, 1);
If none of the four above is an option (or even if they where!) I would strongly suggest using Googles own library found in Google Play services under the namespace com.google.android.gms.vision.barcode. It scans the codes locally, fast and robust, and you have full control of the source code in just a few classes.
For a simple example check out Android QR Code Reader Made Easy. That should get you up and running in no time! There's also further reading linked at the end of the post for advanced examples.
I'm building an application to view pdf's through a browser without the need of a plugin on mobile devices. I tried ImageMagick and ghostscript to covert the pages to images but they are far too large and text becomes unclear. I see website offering a service of converting pdf's into html and do a descent job but I can't find an example of how this is accomplished. Any help is much appreciated. Thanks!
EDIT: I seem to have read the question backwards. In this case it might be best to parse through the PDF and then format some HTML based on what you find. I believe the javapdf option is capable of this, but I haven't used any of these so I am not sure. If worse comes to worst and you can't find software to disassemble a PDF, you might be able to write your own disassembler in Java or PHP by reading the PDF specification. Best of luck!
http://www.adobe.com/devnet/pdf/pdf_reference.html - PDF Specification (Adobe Modified Version, because they are most popular you may want to support their extensions)
-- OLD -- These websites probably write their own proprietary software to do the trick. If you are truly interested in this undertaking, I would suggest parsing the HTML to get the data and style information and using it to format some sort of PDF writer APIs. A quick Google search yields the following: -- END OLD --
http://www.cutepdf.com/Solutions/
http://ruby-pdf.rubyforge.org/pdf-writer/doc/index.html
http://asprise.com/product/javapdf/
If you are looking at converting PDF to HTML and planning to run the conversion on a server, then you can try pdf2html. It is a program packaged as part of poppler-utils. I do not know how the program accomplishes it.
I was googling and came across the below link explaining how scridb.com implements conversion.
http://coding.scribd.com/2010/06/01/the-perils-of-stacking/