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how to decide if you got a good read?

Jul 21, 2013 at 11:40 PM
first off once micjahn gave me the clue to make it work in my example this software is incredible. It is as fast as and gives better results than the leadtool package I am currently using. If testing continues like this I have found my new barcode software.

I do have a couple of issues and need advise.

on 3 of the pages I read the user had put a blank label over the barcode but left just a very small part of it showing on the top. I mean just a few pixels. zxing read it but returned a bad value. I went to investigate to see if I could calculate height from point1.y - point0.y but found the values were the same regardless if it was a good read or bad. Logically I would not think that so, maybe a bug? One thing all the bad reads did have in common is point1.x - point0.x resulted in a negative value. As of now I am using this characteristic as my determination I did not really get a good read. Now I have not tested for upside down or sideways barcodes so this might be a bad indicator to use. In some barcode or ocr software there is a confidence index. Is there something I can use to give me a better indicator if I got a good read?

I tried the crop feature but it did not work. I think I saw somewhere the feature does not work with 1 bit bitmaps? No biggie since I did the cropping myself with freeimage.

I didn't know what dumpblackpoint did so i tried it. The program just hung like it entered a infinite loop or I just ran out of patience in about five minutes.
Jul 22, 2013 at 7:18 PM
ZXing doesn't have such kind of indicator which says something about the barcode scanning result quality.
If you have a negative value for point1.x - point0.x you should check the orientation hint in the results metadata.
Perhaps the barcode was rotated by 180 degrees or is read from right to left.

Cropping should work. For 1 bit bitmaps, too. It would be great if you can point me to a sample image and the code which you tried.

Dump blackpoint is a feature of the command line decoder. If it is set it will write a image file with the original filename and the
extension ".mono.png". It contains some pictures from the image processing stages (like the monochrome version from the binarizer).