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How do I colorize a grayscale BitmapImage in WPF (preferably) using the MVVM pattern?

This is the DataTemplate that I use in my ItemsControl

<ItemsControl ItemsSource="{Binding Items}">
    <ItemsControl.ItemsPanel>
        <ItemsPanelTemplate>
            <Canvas />
        </ItemsPanelTemplate>
    </ItemsControl.ItemsPanel>
    <ItemsControl.ItemTemplate>
        <DataTemplate>
            <Image Source="{Binding Image}">
                <Image.RenderTransform>
                    <ScaleTransform RenderOptions.BitmapScalingMode="HighQuality" ScaleX="{Binding ScaleX}" ScaleY="{Binding ScaleY}" />
                </Image.RenderTransform>
            </Image>
        </DataTemplate>
    </ItemsControl.ItemTemplate>
    <ItemsControl.ItemContainerStyle>
        <Style>
            <Setter Property="Canvas.Left" Value="{Binding X}" />
            <Setter Property="Canvas.Top" Value="{Binding Y}" />
            <Setter Property="Canvas.ZIndex" Value="{Binding Z}" />
        </Style>
    </ItemsControl.ItemContainerStyle>
</ItemsControl>

I've looked at MatrixTransform but that seems to be only used for skewing / rotating the image?

This is what I've used in Java to achieve the same:

public static void colorize(BufferedImage image, Color maskColor)
{
    for (int x = 0; x < image.getWidth(); x++)
    {
        for (int y = 0; y < image.getHeight(); y++)
        {
            int pixel = image.getRGB(x, y);
            if( (pixel >> 24) == 0x00 )
                continue;

            Color color = new Color(pixel);
            float red   = (color.getRed()   / 255.0F) * (maskColor.getRed()   / 255.0F);
            float green = (color.getGreen() / 255.0F) * (maskColor.getGreen()   / 255.0F);
            float blue  = (color.getBlue()  / 255.0F) * (maskColor.getBlue()   / 255.0F);

            color = new Color(red, green, blue);
            int rgb = color.getRGB();
            image.setRGB(x, y, rgb);
        }
    }
}

What would be the best way to colorize a grayscale image? I am relatively new to WPF.

Wesley
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  • Not sure what you are asking here. How would a WPF Transform ever change colors of a bitmap? That makes absolutely no sense. Just as setting `RenderOptions.BitmapScalingMode="HighQuality"` on a ScaleTransform. – Clemens Apr 02 '18 at 12:42
  • If that is not set it is rendered as blurry edges. – Wesley Apr 02 '18 at 12:43
  • And what is a "colorized grayscale image" at all? Please explain. – Clemens Apr 02 '18 at 12:44
  • You need to set `BitmapScalingMode` in places such as `ImageSource`,`BitmapImage`,`ImageBrush` – Software Dev Apr 02 '18 at 12:44
  • Oh @clemens....you are right.....Respect ur WPF knowledge always – Software Dev Apr 02 '18 at 12:45
  • You'd have to translate your 255 grades of gray - or whatever you have in your bitmap into colours or a colour gradient. That wouldn't be in a transform. I suppose it could be in a custom shader effect. – Andy Apr 02 '18 at 12:51
  • @Clemens I've added a Java example. Hopefully that will clarify what I am trying to achieve. – Wesley Apr 02 '18 at 12:53
  • Do the same in WPF/C# with a WriteableBitmap, or pass the pixel array to [BitmpaSource.Create](https://msdn.microsoft.com/en-us/library/ms616045(v=vs.110).aspx). – Clemens Apr 02 '18 at 12:56
  • This thread discusses how to get the bytes https://stackoverflow.com/questions/1176910/finding-specific-pixel-colors-of-a-bitmapimage – Andy Apr 02 '18 at 12:59
  • @Andy I know I can colorize it in C# but I was looking for a XAML solution. – Wesley Apr 02 '18 at 13:04
  • "I know I can colorize it in C#" That's good, because there is no built-in "XAML solution". You may probably use a Binding Converter, which however is also written in C#. – Clemens Apr 02 '18 at 13:15
  • I think you could encapsulate the code in a custom shader but you'd still be writing code. Just in a different place and using a relatively rare technique. – Andy Apr 02 '18 at 13:19
  • @Andy Sounds like a proper solution as I felt 'preprocessing' the image is hacky as it limits reusing it (which is part of my use case, multiple colors). Any pointers for resources I can read upon to implement this? – Wesley Apr 02 '18 at 13:24
  • I've never written an effect myself but you could start your research by reading this https://www.codeproject.com/Articles/71617/Getting-Started-with-Shader-Effects-in-WPF – Andy Apr 02 '18 at 13:57

0 Answers0