Change Contrast through Scrollbar in VB .NET

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This topic and its replies were posted before the current version of LEADTOOLS was released and may no longer be applicable.

#1 Posted : Monday, April 24, 2006 8:24:56 AM(UTC)

dsubryan

Groups: Registered
Posts: 15

Hello,

I currently have an image displayed in RasterImageViewer and I have a scrollbar to change the contrast of the image. The scrollbar changes the contrast of the image when it is scrolled upwards. But it does not restore the contrast when the scrollbar is moved downwards. How do I restore the contrast? I am using the following function to change the contrast (found in the help file).

Private Sub ChangeContrastTest(ByVal image As Leadtools.IRasterImage, ByVal intContrast As Integer)

   commandContrast.Contrast = intContrast
   TextBox1.Text = intContrast
   commandContrast.Run(image)

End Sub

Regards,
David


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#2 Posted : Wednesday, April 26, 2006 1:00:52 AM(UTC)

Maen Hasan

Groups: Registered, Tech Support
Posts: 1,326

Was thanked: 1 time(s) in 1 post(s)

Hello David,

This is normal behavior. Because when you move the scrollbars upwards and raise the contrast of the image, you get a new image with a new contrast value. Then you reduced the contrast with the same amount, you will process the new image (new contrast), not the old image.
However, to adjust the display, use the PaintIntensity, PaintContrast, and PaintGamma properties. These methods affect the display of all images. They are not really part of the image processing group, because they do not affect the image. Nevertheless, these methods can be more useful than the image processing methods when the need for brightness and contrast improvement is device-specific, rather than image-specific.

So, you may change the RasterImage.PaintContrast Property value to control the contrast of the image.

Please try the above instructions and let me know if this helps.

Thanks,
Maen Badwan
LEADTOOLS Technical Support

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