Question

我有以下代码可以转换图像的像素：

使用ColorMatrix进行转换

 Bitmap bmpOut = null;

if (DisplayImage == null)
{
    return;
}

bmpOut = GetBitmapFromImageSoure(OriginalImage.Source);

Bitmap originalImage = bmpOut;
Bitmap adjustedImage = new Bitmap(bmpOut.Width, bmpOut.Height);
float brightness = (float)BrightnessSlider.Value;
float contrast = (float)ContrastSlider.Value;
float gamma = (float)GammaSlider.Value;
float alpha = (float)AlphaSlider.Value;

float adjustedBrightness = brightness - 1.0f;

// create matrix that will brighten and contrast the image
float[][] ptsArray ={
                    new float[] {contrast, 0, 0, 0, 0}, // scale red
                    new float[] {0, contrast, 0, 0, 0}, // scale green
                    new float[] {0, 0, contrast, 0, 0}, // scale blue
                    new float[] {0, 0, 0, alpha, 0},    // scale alpha
                    new float[] {adjustedBrightness, adjustedBrightness, adjustedBrightness, 0, 1}};    // brightness

ImageAttributes imageAttributes = new ImageAttributes();

imageAttributes.ClearColorMatrix();
imageAttributes.SetColorMatrix(new ColorMatrix(ptsArray), ColorMatrixFlag.Default, ColorAdjustType.Bitmap);
imageAttributes.SetGamma(gamma, ColorAdjustType.Bitmap);

Graphics g = Graphics.FromImage(adjustedImage);

g.DrawImage(originalImage, new System.Drawing.Rectangle(0, 0, adjustedImage.Width, adjustedImage.Height)
    , 0, 0, originalImage.Width, originalImage.Height,
    GraphicsUnit.Pixel, imageAttributes);

this.DisplayImage.Source = ConvertToBitmapImage(adjustedImage);

更改每个像素以转换为灰度

Bitmap original = GetBitmapFromImageSoure(OriginalImage.Source);
Bitmap converted = (Bitmap)original.Clone();

System.Drawing.Color c;

for (int i = 0; i < converted.Width; i++)
{
    for (int j = 0; j < converted.Height; j++)
    {
        c = converted.GetPixel(i, j);

        byte gray = (byte)(.299 * c.R + .587 * c.G + .114 * c.B);

        converted.SetPixel(i, j, System.Drawing.Color.FromArgb(gray, gray, gray));
    }
}

DisplayImage.Source = ConvertToBitmapImage(converted);

第一种方法是更改由滑块控制的图像的亮度，伽玛和对比度，并立即变换图像。

第二种方法只需要一个复选框即可花相同的时间处理同一张图像。

为什么要比使用循环中的每个像素更快地使用颜色矩阵？它如何更好地工作？

使用颜色矩阵或通过位图转换图像之间的区别

0 个答案: