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#1 Posted : Monday, December 6, 2010 7:07:09 AM(UTC)

amurray  
amurray

Groups: Registered
Posts: 12


When I print to the virtual printer with dithering code enabled, the first page of the attached document comes out negative -- black on white. If I comment out the dithering code, the image is rendered correctly.

This happens no matter what dithering method I use: even if I set it to RasterDitheringMethod.None, the first page will be printed as a negative.

What's going on?

void printer_JobEvent(object sender, Leadtools.Printer.JobEventArgs e)
{
if (e.JobEventState == Leadtools.Printer.EventState.JobStart) {
this.currentPageNumber = 0;
}
else if (e.JobEventState == Leadtools.Printer.EventState.JobEnd) {
//// dither to 1bpp before saving
//var ditherer = new Leadtools.ImageProcessing.ColorResolutionCommand();
//ditherer.BitsPerPixel = 1;
//ditherer.DitheringMethod = Leadtools.RasterDitheringMethod.StevensonArce;
//ditherer.Run(currentImage);

// save the file to disk
string filename = Path.GetTempFileName();
codecs.Save(currentImage, filename, Leadtools.RasterImageFormat.CcittGroup4, 1);
currentImage.Dispose();

// pass the image off to the DTI application itself
LaunchImageIntoDTI(filename);

return;
}
}
File Attachment(s):
prints_negative.pdf (824kb) downloaded 22 time(s).
 

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#2 Posted : Monday, December 6, 2010 8:23:20 AM(UTC)

amurray  
amurray

Groups: Registered
Posts: 12


Um. Excuse me. I meant "white on black", of course. White text in the virtual printer rendered document, on a black background, the opposite of the coloring of the original document.
 
#3 Posted : Wednesday, December 8, 2010 6:01:11 AM(UTC)

Adam Boulad  
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Can you answer the following questions:
1) Which LEADTOOLS version (15, 16.5, 17, etc.) are you using?
2) If you try to open the PDF with our pre-built .NET Main Demo that ships with the toolkit and try to use the Color Resolution option from the Color => Transform menu, does it show the same behavior?
3) What is the build number (file version info) of the Leadtools.dll?
 
#4 Posted : Wednesday, December 8, 2010 7:45:25 AM(UTC)

amurray  
amurray

Groups: Registered
Posts: 12


1. LeadTools 17

2. If I save the transformed image to disk as a 1bpp CCITT4 TIF and open the tif, the first page is negative. If I save the image as a TIF without having run a transform, the first page of the TIF is not a negative.

3. 17.0.0.10
 
#5 Posted : Thursday, December 9, 2010 4:39:39 AM(UTC)

Adam Boulad  
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I tried the following:
1- Browse to the following location:
Start Menu => Programs => LEADTOOLS 17 => .NET Class Libraries =>.NET Framework => 01 Imaging => 01 Main Demo
2- Open the Main 32-bit Demo.
3- Choose the 'File' => 'Open' button, and check the 'Show options dialog on open'.
4- Browse to the PDF file and press Open
5- The 'File Load Options' dialog shows, set the 'Resolution' to 300 in the 'Rasterize Document' tab.
6- Choose the 'Color Resolution' option from the Color => Transform menu.
7- Choose the following properties:
- Bits Per Pixels: 1
- Palette: Fixed
- Dither: Stevenson-Arc
I got correct results from the conversion. If you try the same steps, is the result correct? If not, please send me the a screenshot of the result you are getting and the output image in a ZIP or RAR file to support@leadtools.com
 
#6 Posted : Monday, December 13, 2010 6:26:11 AM(UTC)

amurray  
amurray

Groups: Registered
Posts: 12


Adding a line to my code to specifically use a fixed palette seems to address the issue.

ditherer.PaletteFlags = Leadtools.ImageProcessing.ColorResolutionCommandPaletteFlags.Fixed;
 
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