图片灰度处理

一、WPF灰度处理（转）

文章的内容是来自微软中文技术论坛的一个帖子,当时是想将一段将图片灰度处理的代码转换为XAML的一个样式,在这里要谢谢

Xiao Yan Qiang、Sheldon _Xiao、shixin的热情回答,现在将他们的回答贴出来供大家学习参考.内容如下:

提问: 这个功能如何写成一个样式,将一个窗体内所有的Image控件的图片格式都转换为Gray8

BitmapImage bitmapImage = new BitmapImage(new Uri("D:\Face.jpg"));
FormatConvertedBitmap newFormatedBitmapSource = new FormatConvertedBitmap();
newFormatedBitmapSource.BeginInit();
newFormatedBitmapSource.Source = bitmapImage;
newFormatedBitmapSource.DestinationFormat = PixelFormats.Gray8;
newFormatedBitmapSource.EndInit();
img.Source = newFormatedBitmapSource;
this.Content = img;

Xiao Yan Qiang的回答:

public class ImageAttached
{
    // Gray8附加属性，Gary8图片样式的"开关"

public static readonly DependencyProperty Gray8Property =
        DependencyProperty.RegisterAttached("Gray8", typeof(bool), typeof(ImageAttached),
            new FrameworkPropertyMetadata((bool)false,
                new PropertyChangedCallback(OnGray8Changed)));

    public static bool GetGray8(DependencyObject d)
    {
        return (bool)d.GetValue(Gray8Property);
    }

    public static void SetGray8(DependencyObject d, bool value)
    {
        d.SetValue(Gray8Property, value);
    }

    private static void OnGray8Changed(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        Image currentImage = d as Image;
        if (currentImage == null)
        {
            return;
        }

        bool isGray8 = (bool)d.GetValue(Gray8Property);

        if (isGray8)
        {
            // 附加BitmapSourceBackup属性，备份当前BitmapSource，以备恢复用

BitmapSource backupBitmapSource = (currentImage.Source as BitmapSource).CloneCurrentValue();
            d.SetValue(BitmapSourceBackupProperty, backupBitmapSource);

            // 建立Gray8的BitmapSource

FormatConvertedBitmap newFormatedBitmapSource = new FormatConvertedBitmap();
            newFormatedBitmapSource.BeginInit();
            newFormatedBitmapSource.Source = currentImage.Source as BitmapSource;
            newFormatedBitmapSource.DestinationFormat = PixelFormats.Gray8;
            newFormatedBitmapSource.EndInit();

            // 替换ImageSource

currentImage.Source = newFormatedBitmapSource;
        }
        else
        {
            // 图像恢复操作

object obj = currentImage.GetValue(BitmapSourceBackupProperty);
            if (obj == null)
            {
                return;
            }

            BitmapSource bs = obj as BitmapSource;
            if (bs == null)
            {
                return;
            }

            currentImage.Source = bs;
        }
    }

    // 备份用源图像的附加属性，当Gray8变更时，自动附加

public static readonly DependencyProperty BitmapSourceBackupProperty =
        DependencyProperty.RegisterAttached("BitmapSourceBackup", typeof(BitmapSource), typeof(ImageAttached),
            new FrameworkPropertyMetadata(null));

    public static BitmapSource GetBitmapSourceBackup(DependencyObject d)
    {
        return (BitmapSource)d.GetValue(BitmapSourceBackupProperty);
    }

    public static void SetBitmapSourceBackup(DependencyObject d, BitmapSource value)
    {
        d.SetValue(BitmapSourceBackupProperty, value);
    }
}

然后XAML里添加 local:ImageAttached.Gray8="True" 

        <Image xmlns:local="clr-namespace:WpfImageGray8Sample" Source="/WpfImageGray8Sample;component/Images/44537119.jpg" local:ImageAttached.Gray8="True" />

这样就可以方便控制Gray8了。

---

Sheldon _Xiao

的回答:

推荐了一个链接: http://www.rikware.com/post/Setting-FormatConvertedBitmap-Source-via-Binding.aspx

里面也是用转换器实现

---

shixin的回答:

<Window x:Class="MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:y="clr-namespace:WpfApplication1"  Title="MainWindow" Height="350" Width="525">
            <Window.Resources>
                <y:GrayImage x:Key="GrayImage" />
            </Window.Resources>
            <Grid>
                <Image Source="{Binding RelativeSource={RelativeSource Self}, Path=Tag, Converter={StaticResource GrayImage}}" Tag="C:Test.jpg" />
            </Grid>
        </Window>

xaml部分还可以写成这样

<Window.Resources>
            <y:GrayImage x:Key="GrayImage" />
            <Style TargetType="{x:Type Image}">
                <Setter Property="Source" Value="{Binding RelativeSource={RelativeSource Self}, Path=Tag, Converter={StaticResource GrayImage}}" />
            </Style>
        </Window.Resources>
        <Grid>
            <Image Tag="C:Test.jpg" />
        </Grid>

Public Class GrayImage
    Implements IValueConverter
    Public Function Convert(ByVal value As Object, ByVal targetType As Type, ByVal parameter As Object, ByVal culture As Globalization.CultureInfo) As Object Implements IValueConverter.Convert
        Try
            Dim newFormatedBitmapSource As New FormatConvertedBitmap
            newFormatedBitmapSource.BeginInit()
            newFormatedBitmapSource.Source = New BitmapImage(New Uri(value.ToString))
            newFormatedBitmapSource.DestinationFormat = PixelFormats.Gray8
            newFormatedBitmapSource.EndInit()
            Convert = newFormatedBitmapSource
        Catch
            Convert = Nothing
        End Try
    End Function
    Public Function ConvertBack(ByVal value As Object, ByVal targetType As Type, ByVal parameter As Object, ByVal culture As Globalization.CultureInfo) As Object Implements IValueConverter.ConvertBack
        ConvertBack = value
    End Function
End Class

二、Windos8和WindowsPhone通过更改像素点颜色更改图片灰度

private async void Button_Click(object sender, RoutedEventArgs e)
       {
           // 实例化一个 300*300 的 WriteableBitmap，并将其作为 Image 控件的图片源
           WriteableBitmap writeableBitmap = new WriteableBitmap(300, 300);
           image2.Source = writeableBitmap;

           StorageFile file = await StorageFile.GetFileFromApplicationUriAsync(new Uri("ms-appx:///Assets/2.jpg"));
           using (IRandomAccessStream fileStream = await file.OpenAsync(FileAccessMode.Read))
           {
               // 将指定的图片转换成 BitmapDecoder 对象
               BitmapDecoder decoder = await BitmapDecoder.CreateAsync(fileStream);

               // 通过 BitmapTransform 缩放图片的尺寸
               BitmapTransform transform = new BitmapTransform()
               {
                   ScaledWidth = Convert.ToUInt32(writeableBitmap.PixelWidth),
                   ScaledHeight = Convert.ToUInt32(writeableBitmap.PixelHeight)
               };

               // 获取图片的 PixelDataProvider 对象
               PixelDataProvider pixelData = await decoder.GetPixelDataAsync(
                   BitmapPixelFormat.Bgra8,
                   BitmapAlphaMode.Straight,
                   transform,
                   ExifOrientationMode.IgnoreExifOrientation,
                   ColorManagementMode.DoNotColorManage);

               // 获取图片的像素数据，由于之前指定的格式是 BitmapPixelFormat.Bgra8，所以每一个像素由 4 个字节组成，分别是 bgra
               byte[] sourcePixels = pixelData.DetachPixelData();
               for (int i = 0; i < sourcePixels.Length; i+=4)
               {                  
                     
                     byte B = sourcePixels[i];
                     byte G = sourcePixels[i + 1];
                     byte R = sourcePixels[i + 2];
                     byte A = sourcePixels[i + 3]; 
                     byte GrayValue = (byte)(R * 0.299 + G * 0.587 + B * 0.114);
                    sourcePixels[i]=GrayValue;
                    sourcePixels[i + 1]=GrayValue;
                    sourcePixels[i + 2]=GrayValue;
                    sourcePixels[i + 3]=0xFF; 
               }
               // 将修改后的像素数据写入 WriteableBitmap 对象的像素缓冲区（WriteableBitmap 使用的是 BGRA 格式）
               using (Stream stream = writeableBitmap.PixelBuffer.AsStream()) // IBuffer.AsStream() 为来自 System.Runtime.InteropServices.WindowsRuntime.WindowsRuntimeBufferExtensions 中的扩展方法
               {
                   await stream.WriteAsync(sourcePixels, 0, sourcePixels.Length);
               }
           }
           // 用像素缓冲区的数据绘制图片
           writeableBitmap.Invalidate();
       }