Re: Inverted Datamatrix(please read before you go off haha)

[Sean Owen]

It is not different for Data matrix. The same idea applies, just flip all the pixels over at some stage in your pipeline.

[Nathan Kellert]

thanks sean. 

I got this for ( int i = 0; i < size; i++) {

        result[i] = static_cast<unsigned char>(255 - result[i]);

    } 

right before return result in ArrayRef<char> GreyscaleLuminanceSource::getMatrix() const 

on iOS.

Not sure where to begin on android. Any ideas?

[Sean Owen]

There's already a setting to invert the image, using the camera hardware:

https://code.google.com/p/zxing/source/browse/trunk/android/src/com/google/zxing/client/android/camera/CameraConfigurationManager.java#121

or you could look at reversing the luminance values in the same way right before the call to...

https://code.google.com/p/zxing/source/browse/trunk/core/src/com/google/zxing/PlanarYUVLuminanceSource.java#39

There are smarter ways too but these are the easiest by far.

[Nathan Kellert]

Tried to follow this. For some reason it didn't work. Im thinking my real issue is that I need to recompile my core information. I noticed you wrote most of this. Pretty impressive. I definitely appreciate you taking the time to help me. Perhaps I just get some rest. I think Im still stuck in ios mode and am just not seeing where Im going wrong. Either that or just pay someone haha. 

https://code.google.com/p/zxing/issues/detail?id=952

[Wayman, Jack A Jr COL USARMY (US)]

Nathan,
My comments may not be useful. I applaud and respect your work.

You're trying to read an inverse color scheme. However, your client's prior assumption that a black background requires an inverse color scheme is a false assumption.

The DataMatrix has a quiet zone one module wide on the outside edges. It is parrt of the symbology. It can't be seen if the image is on a white background. That's why most people don't know it's there. However, I've seen many instances of a standard color scheme (with a white quiet zone) on a black background. I've also seen an inverse color schemes on black and white backgrounds.

I don't know a good reason for using inverse color schemes. But they exist, so, there is a need for someone to solve the problem you are solving and I applaud your work. However, the problem could also be solved if people knew about the quiet zone. It would also help if they used the terms "standard" and "inverse" instead of "black on white" and "white on back", which pertain to ink application, not the color scheme.

Nevertheless, I applaud your work.

Respectfully,
Jake
 

From: Nathan Kellert [mailto:na...@yoursitedesign.net]
Sent: Thursday, April 18, 2013 05:31 AM
To: zx...@googlegroups.com <zx...@googlegroups.com>
Subject: Inverted Datamatrix(please read before you go off haha)
 

Ok so I have a client that is a contractor for making industrial grade indestructible datamatrix dots. Only problem is that the material is black. So the print HAS to be white. Now I have torn the web apart looking for the solution to this and cannot seem to find any. I am working with the iPhone port and the Android port. Im pretty far along with getting everything working. I even added ARM and Storyboard to the iOS version if you guys what to have a look. 

Now Ive found this

http://stackoverflow.com/questions/9249526/invert-pixels-zxing

and this

https://code.google.com/p/zxing/issues/detail?id=952

I see that these are good for use with QR but not necessarily how the DataMatrix is programmed. Anyone can help? Id be willing to pay. Thanks!

 

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[Nathan Kellert]

Well the technology that my client uses makes little tiny barcodes that are virtually indestructible. Problem is the material itself is black...so the print has to be white. So you are right...I need white on black. I actually got it working last night. Finally. Haha this has been difficult because I am simultaneous working with ios and android. So going back and forth has caused me to work a little less efficiently than normal.  

Id really like to thank you guys for helping me out so much and pointing me in the right direction! Oh I also have a question...or really advice...Ill make a new question for that though.

By the way I went ahead and coded it the same way I did with the ios and actually inverted the pixels upon read fail. Worked like a charm. 

[Sean Owen]

Yes that sounds right. By the way Jake's suggestion was to print a white square on the black material, then print a black-on-white barcode on that white square.

[Wayman, Jack A Jr COL USARMY (US)]

I've also seen the reverse where black ink prints on white print stock for a circular die-cut barcode label. They printed a black square larger than the die-cut circle but left a white square in the center large enough to print a standard color scheme in black ink.

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