CODEWITHSUNDEEP
c#.netwpfgraphicsbitmap
dodgy_coder
dodgy_coder

Reputation: 13063

Draw a colour bitmap as greyscale in WPF

I'm looking for a way to draw a bitmap to a WPF DrawingContext as greyscale. I'd like to be able to draw it at the given x,y location and scale it to a given width and height. 256 levels of grey (8-bit greyscale) is good enough. I have a colour bitmap file on disk which will be either bmp, png or jpg format.

Upvotes: 1

Views: 1159

Answers (2)

kidshaw
kidshaw

Reputation: 3461

You can do this using an effect - possibly not as performant as pure code, but offers flexibility.

<Image Source="../Images/ChartSample.png" Stretch="Uniform" Margin="5">
<Image.Effect>
    <ee:ColorToneEffect DarkColor="Black" LightColor="White" ToneAmount="0" Desaturation="1" />
</Image.Effect>

Where you reference namespace as

xmlns:ee=”http://schemas.microsoft.com/expression/2010/effects&#8221;

Upvotes: 0

dodgy_coder
dodgy_coder

Reputation: 13063

using System;
using System.Windows;
using System.Windows.Media;
using System.Windows.Media.Imaging;

void DrawBitmapGreyscale(DrawingContext dc, string filename, int x, int y, int width, int height)
{
    // Load the bitmap into a bitmap image object
    BitmapImage bitmap = new BitmapImage();
    bitmap.BeginInit();
    bitmap.CacheOption = BitmapCacheOption.OnLoad;
    bitmap.UriSource = new Uri(filename);
    bitmap.EndInit();

    // Convert the bitmap to greyscale, and draw it.
    FormatConvertedBitmap bitmapGreyscale = new FormatConvertedBitmap(bitmap, PixelFormats.Gray8, BitmapPalettes.Gray256, 0.0);
    dc.DrawImage(bitmapGreyscale, new Rect(x, y, width, height));
}

Upvotes: 2

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