c# – 如何使用滑块调整图像的亮度和对比度?
作者:互联网
我有一个图像,我想通过xaml中的滑块调整其亮度和对比度.
我不知道从哪里开始.任何帮助将不胜感激.
我正在努力实现这一点
public WriteableBitmap ChangeBrightness(WriteableBitmap inputBitmap, double brightnessValue )
{
double Value = brightnessValue;
var inputPixels = inputBitmap.Pixels;
for (int i = 0; i < inputPixels.Length; i++)
{
// Extract color components
var c = inputBitmap.Pixels[i];
var a = (byte)(c >> 24);
var r = (byte)(c >> 16);
var g = (byte)(c >> 8);
var b = (byte)(c);
int ri = r + (int)Value;
int gi = g + (int)Value;
int bi = b + (int)Value;
// Clamp to byte boundaries
r = (byte)(ri > 255 ? 255 : (ri < 0 ? 0 : ri));
g = (byte)(gi > 255 ? 255 : (gi < 0 ? 0 : gi));
b = (byte)(bi > 255 ? 255 : (bi < 0 ? 0 : bi));
inputBitmap.Pixels[i] = (a << 24) | (r << 16) | (g << 8) | b;
}
return inputBitmap;
}
但我认为这是没有用的,我没有找到任何有用的文章.
解决方法:
见Formula For Adjusting Brightness
使用添加公式,您在程序中缺少2个零件.
第1部分:创建一个新的可写位图而不是修改输入位图(返回此新位图)
第2部分:您必须保存位图的原始副本(亮度不可逆,如上面的链接所说)
一个非常慢的实现,让你开始.大多数这些东西都可以在MSDN上找到,如果你只是花一些时间阅读(如果你想让程序比Hello World更先进,你需要进入这个习惯).
<StackPanel>
<Image x:Name="myImage" Stretch="None" Source="Assets/bling.png"/>
<Slider x:Name="mySilder" ValueChanged="mySilder_ValueChanged"></Slider>
</StackPanel>
// namespaces
using Windows.UI.Xaml.Media.Imaging;
using Windows.Storage;
// our copy of the image
WriteableBitmap copy;
public MainPage()
{
this.InitializeComponent();
}
private async void Page_Loaded(object sender, RoutedEventArgs e)
{
// storage file for the image (load it)
StorageFile file = await StorageFile.GetFileFromApplicationUriAsync(new Uri("ms-appx:///Assets/bling.png"));
// create a bitmap image
BitmapImage bi = new BitmapImage();
using (
// Open a stream for the selected file.
Windows.Storage.Streams.IRandomAccessStream fileStream =
await file.OpenAsync(Windows.Storage.FileAccessMode.Read))
{
// load the image into the BitmapImage
await bi.SetSourceAsync(fileStream);
// create a copy of the image
copy = new WriteableBitmap(bi.PixelWidth, bi.PixelHeight);
// load the image into writeablebitmap copy
fileStream.Seek(0);
await copy.SetSourceAsync(fileStream);
}
}
private WriteableBitmap ChangeBrightness(WriteableBitmap source, byte change_value)
{
WriteableBitmap dest = new WriteableBitmap(source.PixelWidth, source.PixelHeight);
byte[] color = new byte[4];
using (Stream s = source.PixelBuffer.AsStream())
{
using (Stream d = dest.PixelBuffer.AsStream())
{
// read the pixel color
while (s.Read(color, 0, 4) > 0)
{
// color[0] = b
// color[1] = g
// color[2] = r
// color[3] = a
// do the adding algo per byte (skip the alpha)
for (int i = 0; i < 4; i++)
{
if ((int)color[i] + change_value > 255) color[i] = 255; else color[i] = (byte)(color[i] + change_value);
}
// write the new pixel color
d.Write(color, 0, 4);
}
}
}
// return the new bitmap
return dest;
}
private void mySilder_ValueChanged(object sender, RangeBaseValueChangedEventArgs e)
{
if (this.mySilder != null)
{
// deterime the brightness to add
byte value_to_add = (byte)((this.mySilder.Value / this.mySilder.Maximum) * 255);
// get the new bitmap with the new brightness
WriteableBitmap ret = ChangeBrightness(copy, value_to_add);
// set it as the source so we can see the change
this.myImage.Source = ret;
}
}
代码在行动
如果您正在寻找“bling.png”,请访问:bling.png
标签:c,xaml,windows-store-apps,winrt-xaml 来源: https://codeday.me/bug/20190628/1319737.html