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#1 Posted : Friday, March 14, 2008 10:23:54 AM(UTC)


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This is probably a shot in the dark, but I thought I'd try asking anyways. :)

The HP Scanjet 8250 has a feature called "Auto Threshold" that you can click on their UI. This feature basically auto detects how light/dark the document is and estimates a value for the threshold setting of a black and white image. Does LEADTOOLS/TWAIN support this? If not, is there a way that I mimick this feature using LEADTOOLS capabilities from v14.5 for .NET without affecting other scanned documents with barcodes?

The reason I'm asking is because some of the users are reporting that if this feature is not available, the text on carbon receipt copies are not visible. It's like someone took whiteout and went crazy on the page!

I have tried setting a standard threshold value of 140 which helps the text show, but it messes up all other documents making the barcodes unreadable.

Please, please help!

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#2 Posted : Sunday, March 16, 2008 1:36:02 AM(UTC)

Qasem Lubani  

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nearest thing I could find in the Twain specification is the ICAP_AUTOBRIGHT
capability. If this capability is not supported in your driver, or if it
doesn't perform the function you need, the standard Image Threshold capability
in Twain does not have a special value that means 'automatically detect'. It only allows a non-negative value in the range 0 to 255.

means the feature you have is implemented in the scanner's software either as a
custom capability in the Twain driver, or as post-processing feature in the software.


If it's
a custom capability, our toolkit can support custom capabilities, but you will need to obtain technical details for the capability from the manufacturer.


If the feature is implemented as a post-processing
step, you can try to use our image processing functions, such as Auto level and
Auto contrast. In .NET, you can use the AutoColorLevelCommand Class. The
"Type" property of the class allows you to run the function to either perform Contrasting or leveling.
#3 Posted : Monday, March 17, 2008 9:25:05 AM(UTC)


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Posts: 16

I doubt that I will be able to obtain the technical details of the capability from HP. It's hard enough to get tech support with them much less anything else!

This scanner does support ICAP_AUTOBRIGHT, so I have enabled that capability. The AutoColorLevelCommand class also works well. Thanks for your suggestions.
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