Question

我有一个图像，我想将该特定图像的色调修改为特定值。我知道rgb到hsl和hsl到rgb转换数学公式，但我无法将这个东西实现到c＃中。

以下是伪：

for(x=0;x<image_width;x++)
{
  for(y=0;y<image_height;y++)
  {
    Color oldColor=GetColorFromPixel(x,y);
    Color newColor=ModifyHue(oldColor);
    SetColorPixel(x,y,newColor);    
  }
}

由于

Answer 1

由于Color结构已经有GetHue()，GetSaturation()和GetBrightness()，因此从这些值构建颜色会更好。所以我不久前在网上的某个地方找到了以下代码（目前无法再找到它，但它来自微软的家伙博客，他还有一个测试，逐步完成所有KnownColor）。

/// <summary>
/// Creates a Color from alpha, hue, saturation and brightness.
/// </summary>
/// <param name="alpha">The alpha channel value.</param>
/// <param name="hue">The hue value.</param>
/// <param name="saturation">The saturation value.</param>
/// <param name="brightness">The brightness value.</param>
/// <returns>A Color with the given values.</returns>
public static Color FromAhsb(int alpha, float hue, float saturation, float brightness)
{

    if (0 > alpha || 255 < alpha)
    {
        throw new ArgumentOutOfRangeException("alpha", alpha,
          "Value must be within a range of 0 - 255.");
    }
    if (0f > hue || 360f < hue)
    {
        throw new ArgumentOutOfRangeException("hue", hue,
          "Value must be within a range of 0 - 360.");
    }
    if (0f > saturation || 1f < saturation)
    {
        throw new ArgumentOutOfRangeException("saturation", saturation,
          "Value must be within a range of 0 - 1.");
    }
    if (0f > brightness || 1f < brightness)
    {
        throw new ArgumentOutOfRangeException("brightness", brightness,
          "Value must be within a range of 0 - 1.");
    }

    if (0 == saturation)
    {
        return Color.FromArgb(alpha, Convert.ToInt32(brightness * 255),
          Convert.ToInt32(brightness * 255), Convert.ToInt32(brightness * 255));
    }

    float fMax, fMid, fMin;
    int iSextant, iMax, iMid, iMin;

    if (0.5 < brightness)
    {
        fMax = brightness - (brightness * saturation) + saturation;
        fMin = brightness + (brightness * saturation) - saturation;
    }
    else
    {
        fMax = brightness + (brightness * saturation);
        fMin = brightness - (brightness * saturation);
    }

    iSextant = (int)Math.Floor(hue / 60f);
    if (300f <= hue)
    {
        hue -= 360f;
    }
    hue /= 60f;
    hue -= 2f * (float)Math.Floor(((iSextant + 1f) % 6f) / 2f);
    if (0 == iSextant % 2)
    {
        fMid = hue * (fMax - fMin) + fMin;
    }
    else
    {
        fMid = fMin - hue * (fMax - fMin);
    }

    iMax = Convert.ToInt32(fMax * 255);
    iMid = Convert.ToInt32(fMid * 255);
    iMin = Convert.ToInt32(fMin * 255);

    switch (iSextant)
    {
        case 1:
            return Color.FromArgb(alpha, iMid, iMax, iMin);
        case 2:
            return Color.FromArgb(alpha, iMin, iMax, iMid);
        case 3:
            return Color.FromArgb(alpha, iMin, iMid, iMax);
        case 4:
            return Color.FromArgb(alpha, iMid, iMin, iMax);
        case 5:
            return Color.FromArgb(alpha, iMax, iMin, iMid);
        default:
            return Color.FromArgb(alpha, iMax, iMid, iMin);
    }
}

使用此功能，您可以在HSL演示文稿中的HSB（或HSV）颜色显示不内工作。有关它们之间差异的更多信息，请查看this wikipedia article。

Answer 2

如果您只想尝试或性能不重要，最简单的方法是使用Bitmap.GetPixel和Bitmap.SetPixel方法：

var bm = new Bitmap(filename);
for(int x=0;x<bm.Width;x++)
{
  for(y=0;y<bm.Height;y++)
  {
    Color oldColor=bm.GetPixel(x,y);
    Color newColor=ModifyHue(oldColor);
    bm.SetPixel(x,y,newColor);    
  }
}

如果你想要更高效的操作，你应该看一下Bitmap.LockBits方法，该方法修复了内存位置上的整个位图，并允许你直接修改这个内存。

C＃中的图像色调修改

2 个答案: