brightness adjusting on black & white images vb.net

marfi95_at_yahoo.com
Date: 01/06/05 

Date: Thu, 06 Jan 2005 04:46:37 GMT

I'm trying to implement some code in vb.net to allow the user to
adjust the brightness or contrast on an image (through the use of a
slider) that is already black & white in the bitmap. I have tried
to use the colormatrix and even down to the pixel using GetPixel and
SetPixel in system.drawing, but I'm really not up on using gdi+ and
haven't really gotten anywhere. I've seen some examples for VB6, but
I need vb.net.

I know that all the pixels are either 255 or 0 already since its black
and white, but if you are adusting the brightness, how do you decide
which pixels to turn white or black based on how much the user wants
to brighten/darken. I've got code to read & set each pixel, but I
just dont know what to use to decide what to set the new pixel to.

If you someone could post some code or point me to a good example that
explains whats going on, I would be most appreciative.

Thanks,
Mark

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