Bad Barcode detection on high resolution images

Discussions about 1D barcode reading and writing
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Eco
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Bad Barcode detection on high resolution images

Post by Eco » Tue Aug 24, 2010 12:29 pm

Hello GDPicture-Support,

i've recognized a quite strange behaviour when trying to detect barcodes on images with a resolution of 600 DPI (4992x6920 pixels in this case) or greater. Most of the barcodes on such images are not recognized by GDPicture. When i use the resize method to reduce the resolution to a smaller resolution like 300 DPI (2496x3460 pixels), the barcodes are all recognized flawlessly.

Is this a known issue? Or do i have to set a specific property to handle larger images?

Thank you in advance for your help.

Best regards,
Eco

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Loïc
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Re: Bad Barcode detection on high resolution images

Post by Loïc » Tue Aug 24, 2010 3:16 pm

Hi Eco,

Best performances for recognition (OCR or barcode) are usually reach between 200 and 300 DPI.

What I can suggest is it to scale your image to 300 DPI before processing them.

- Create cloned image
- Scale this cloned image to 300 DPI (using the scaleImage method)
- Performs recognition on the scaled image.

This requires some code but it is very easy to implement and usually result on excellent results...

Hope this helps !

Loïc

Eco
Posts: 14
Joined: Thu Apr 29, 2010 10:51 am
Location: Germany

Re: Bad Barcode detection on high resolution images

Post by Eco » Wed Aug 25, 2010 9:01 am

Hello Loic,

thanks for the answer, i think, i will implement it this way, even though this will probably result in a slight performance decrease.

I think, we will do some additional tests and purchase the library in the next days then. :)

Best regards,
Eco

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Loïc
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Re: Bad Barcode detection on high resolution images

Post by Loïc » Wed Aug 25, 2010 12:15 pm

Hi Eco,
even though this will probably result in a slight performance decrease
Not sure dude. OK you have a resize operation to process but in ah other hand you apply OMR to a smaller bitmap. To be tested but I think you should get almost same perfs...

Kind regards,

Loïc

Eco
Posts: 14
Joined: Thu Apr 29, 2010 10:51 am
Location: Germany

Re: Bad Barcode detection on high resolution images

Post by Eco » Wed Aug 25, 2010 2:38 pm

Hello Loic,

i've tried this with "gdImaging.ResizeHeightRatio(iImage, 3500, System.Drawing.Drawing2D.InterpolationMode.Default);" on a tif-file with 25 pages, all 600 DPI. Without scaling the images, the barcode recognition process (on the 600 DPI images) is significantly faster than scaling and recognizing the smaller images.

Best Regards,
Eco

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Loïc
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Re: Bad Barcode detection on high resolution images

Post by Loïc » Wed Aug 25, 2010 2:41 pm

Thank you for the return,

If you send me your image per mail at l.carrere (at) gdpicture (dot) com I will try to find time to investigate your issue. I think we should get similar performances...

Cheers,

Loïc

Eco
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Joined: Thu Apr 29, 2010 10:51 am
Location: Germany

Re: Bad Barcode detection on high resolution images

Post by Eco » Wed Aug 25, 2010 3:05 pm

I've sent you the image.

Best Regards,
Eco

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Loïc
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Re: Bad Barcode detection on high resolution images

Post by Loïc » Tue Aug 31, 2010 10:29 am

Hi Eco,

We have been able to increase the resizing performance bu 70 % on bitonal image. This enhancement will be included in GdPicture.NET 7. Hop we will be able to get same performance as with "non-scaling" recognition...

Kind regards,

Loïc

Eco
Posts: 14
Joined: Thu Apr 29, 2010 10:51 am
Location: Germany

Re: Bad Barcode detection on high resolution images

Post by Eco » Wed Sep 01, 2010 1:00 pm

Thank you for the info. When approximately will version 7 be available?

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Loïc
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Re: Bad Barcode detection on high resolution images

Post by Loïc » Wed Sep 01, 2010 6:06 pm

On 13th September.

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