public TwainImagePixelFlavor PixelFlavor { get; set; } 
Pixel flavor used when acquiring. Possible values are (according to the TWAIN specification): TwainCapabilityValue.PixelFlavorChocolate zero stands for the darkest shade, TwainCapabilityValue.PixelFlavorVanilla zero stands for the lightest shade.
using Leadtools;using Leadtools.Twain;public void ImageEffectsPropertyExample(IntPtr parent){try{TwainSession session = new TwainSession();session.Startup(parent, "manufacturer", "productFamily", "version", "application", TwainStartupFlags.None);TwainProperties props = session.Properties;TwainImageEffectsProperties imageEfx = props.ImageEffects;imageEfx.PixelFlavor = TwainImagePixelFlavor.Vanilla;imageEfx.ColorScheme = TwainColorScheme.BlackWhite;imageEfx.Highlight = 50;imageEfx.Shadow = 50;imageEfx.Brightness = 500;imageEfx.Contrast = 100;string buffer = string.Format("Current used Halftone = {0}", imageEfx.Halftone);MessageBox.Show(buffer);props.ImageEffects = imageEfx;session.Properties = props;session.Shutdown();}catch (Exception ex){MessageBox.Show(ex.Message);}}