Convert to blackandwhite gdimaging v9.4

[asciiman]

hi,
I am creating Colored MultiPageTiff from scanned pages.

Code: Select all

_gdImaging.TwainSetBitDepth( 24 );	// 24 bit
_gdImaging.TwainSetPixelType(GdPicture9.TwainPixelType.TWPT_RGB)

    int xGDImageID = _gdImaging.TwainAcquireToGdPictureImage(this.Handle);
    if (xGDImageID != 0)
    {
        if (_MultiPageID == 0)
            _MultiPageID = _gdImaging.TiffCreateMultiPageFromGdPictureImage(xGDImageID);
        else
            _gdImaging.TiffAppendPageFromGdPictureImage(_MultiPageID, xGDImageID);
	}

I wanna save each page blackandwhite pdf.

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            int BlackAndWhiteImageID = _gdImaging.CreateClonedGdPictureImageI(_MultiPageID);
            _gdImaging.FxBlackNWhite(BlackAndWhiteImageID, GdPicture9.BitonalReduction.OrderedDither);  // NearestColor, OrderedDither, Burke, Stucki, FloydSteinberg
            _gdImaging.ConvertTo1Bpp(BlackAndWhiteImageID);

after saving

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            for (int xIndex = 1; xIndex <= xPageCount; xIndex++)
            {
                _gdImaging.TiffSelectPage(BlackAndWhiteImageID, xIndex);
                _gdImaging.SaveAsPDF(BlackAndWhiteImageID, pdfPath, 
            }

But results are not like BlackAndWhite scanning

Orginal BlackAndWhite

Converted

How can i convert blackandwhite from colored tiff for best result?

[SamiKharma]

Hi,

There are many thresholding (binarization) techniques in image processing, some are good for certain conditions while others aren't and visa-versa.
GdPicture has a good set of thresholding mechanisms, to test them, please check the Binarization Sample Demo application, in which you can load your document and see the result of different binarization techniques.

Best,
Sami

[asciiman]

thnx sir
i try it and i get good result.

best regards