15

画像にシャープフィルタを適用したい。短いチュートリアルのある Web を見つけました。私はC＃でやろうとしたので、ここに私のコードがあります。とにかく、なぜうまくいかないのかを調べてみました。私が何か間違ったことをしているかどうかはわかりません。もしそうなら、それを正常に機能させるために何をすべきか教えてください。ありがとう

        public static Bitmap sharpen(Bitmap image)
    {
        Bitmap sharpenImage = new Bitmap(image.Width, image.Height);

        int filterWidth = 3;
        int filterHeight = 3;
        int w = image.Width;
        int h = image.Height;

        double[,] filter = new double[filterWidth, filterHeight];

        filter[0, 0] = filter[0, 1] = filter[0, 2] = filter[1, 0] = filter[1, 2] = filter[2, 0] = filter[2, 1] = filter[2, 2] = -1;
        filter[1, 1] = 9;

        double factor = 1.0;
        double bias = 0.0;

        Color[,] result = new Color[image.Width, image.Height];

        for (int x = 0; x < w; ++x)
        {
            for (int y = 0; y < h; ++y)
            {
                double red = 0.0, green = 0.0, blue = 0.0;
                Color imageColor = image.GetPixel(x, y);

                for (int filterX = 0; filterX < filterWidth; filterX++)
                {
                    for (int filterY = 0; filterY < filterHeight; filterY++)
                    {
                        int imageX = (x - filterWidth / 2 + filterX + w) % w;
                        int imageY = (y - filterHeight / 2 + filterY + h) % h;
                        red += imageColor.R * filter[filterX, filterY];
                        green += imageColor.G * filter[filterX, filterY];
                        blue += imageColor.B * filter[filterX, filterY];
                    }
                    int r = Math.Min(Math.Max((int)(factor * red + bias), 0), 255);
                    int g = Math.Min(Math.Max((int)(factor * green + bias), 0), 255);
                    int b = Math.Min(Math.Max((int)(factor * blue + bias), 0), 255);

                    result[x, y] = Color.FromArgb(r, g, b);
                }
            }
        }
        for (int i = 0; i < w; ++i)
        {
            for (int j = 0; j < h; ++j)
            {
                sharpenImage.SetPixel(i, j, result[i, j]);
            }
        }
        return sharpenImage;
    }
4

6 に答える 6

26

GetPixel/SetPixel の使用は非常に高価で、パフォーマンスを必要とするシステムには不適切であるため、Daniel の回答を取得し、BitmapData クラスを使用してパフォーマンスのために修正しました。以前のソリューションとまったく同じように機能し、代わりに使用できます。

   public static Bitmap Sharpen(Bitmap image)
    {
        Bitmap sharpenImage = (Bitmap)image.Clone();

        int filterWidth = 3;
        int filterHeight = 3;
        int width = image.Width;
        int height = image.Height;

        // Create sharpening filter.
        double[,] filter = new double[filterWidth, filterHeight];
        filter[0, 0] = filter[0, 1] = filter[0, 2] = filter[1, 0] = filter[1, 2] = filter[2, 0] = filter[2, 1] = filter[2, 2] = -1;
        filter[1, 1] = 9;

        double factor = 1.0;
        double bias = 0.0;

        Color[,] result = new Color[image.Width, image.Height];

        // Lock image bits for read/write.
        BitmapData pbits = sharpenImage.LockBits(new Rectangle(0, 0, width, height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);

        // Declare an array to hold the bytes of the bitmap.
        int bytes = pbits.Stride * height;
        byte[] rgbValues = new byte[bytes];

        // Copy the RGB values into the array.
        System.Runtime.InteropServices.Marshal.Copy(pbits.Scan0, rgbValues, 0, bytes);

        int rgb;
        // Fill the color array with the new sharpened color values.
        for (int x = 0; x < width; ++x)
        {
            for (int y = 0; y < height; ++y)
            {
                double red = 0.0, green = 0.0, blue = 0.0;

                for (int filterX = 0; filterX < filterWidth; filterX++)
                {
                    for (int filterY = 0; filterY < filterHeight; filterY++)
                    {
                        int imageX = (x - filterWidth / 2 + filterX + width) % width;
                        int imageY = (y - filterHeight / 2 + filterY + height) % height;

                        rgb = imageY * pbits.Stride + 3 * imageX;

                        red += rgbValues[rgb + 2] * filter[filterX, filterY];
                        green += rgbValues[rgb + 1] * filter[filterX, filterY];
                        blue += rgbValues[rgb + 0] * filter[filterX, filterY];
                    }
                    int r = Math.Min(Math.Max((int)(factor * red + bias), 0), 255);
                    int g = Math.Min(Math.Max((int)(factor * green + bias), 0), 255);
                    int b = Math.Min(Math.Max((int)(factor * blue + bias), 0), 255);

                    result[x, y] = Color.FromArgb(r, g, b);
                }
            }
        }

        // Update the image with the sharpened pixels.
        for (int x = 0; x < width; ++x)
        {
            for (int y = 0; y < height; ++y)
            {
                rgb = y * pbits.Stride + 3 * x;

                rgbValues[rgb + 2] = result[x, y].R;
                rgbValues[rgb + 1] = result[x, y].G;
                rgbValues[rgb + 0] = result[x, y].B;
            }
        }

        // Copy the RGB values back to the bitmap.
        System.Runtime.InteropServices.Marshal.Copy(rgbValues, 0, pbits.Scan0, bytes);
        // Release image bits.
        sharpenImage.UnlockBits(pbits);

        return sharpenImage;
    }
于 2009-08-24T00:41:10.430 に答える
26 
public static Bitmap sharpen(Bitmap image)
{
    Bitmap sharpenImage = new Bitmap(image.Width, image.Height);

    int filterWidth = 3;
    int filterHeight = 3;
    int w = image.Width;
    int h = image.Height;

    double[,] filter = new double[filterWidth, filterHeight];

    filter[0, 0] = filter[0, 1] = filter[0, 2] = filter[1, 0] = filter[1, 2] = filter[2, 0] = filter[2, 1] = filter[2, 2] = -1;
    filter[1, 1] = 9;

    double factor = 1.0;
    double bias = 0.0;

    Color[,] result = new Color[image.Width, image.Height];

    for (int x = 0; x < w; ++x)
    {
        for (int y = 0; y < h; ++y)
        {
            double red = 0.0, green = 0.0, blue = 0.0;

//=====[REMOVE LINES]========================================================
// Color must be read per filter entry, not per image pixel.
            Color imageColor = image.GetPixel(x, y);
//===========================================================================

            for (int filterX = 0; filterX < filterWidth; filterX++)
            {
                for (int filterY = 0; filterY < filterHeight; filterY++)
                {
                    int imageX = (x - filterWidth / 2 + filterX + w) % w;
                    int imageY = (y - filterHeight / 2 + filterY + h) % h;

//=====[INSERT LINES]========================================================
// Get the color here - once per fiter entry and image pixel.
                    Color imageColor = image.GetPixel(imageX, imageY);
//===========================================================================

                    red += imageColor.R * filter[filterX, filterY];
                    green += imageColor.G * filter[filterX, filterY];
                    blue += imageColor.B * filter[filterX, filterY];
                }
                int r = Math.Min(Math.Max((int)(factor * red + bias), 0), 255);
                int g = Math.Min(Math.Max((int)(factor * green + bias), 0), 255);
                int b = Math.Min(Math.Max((int)(factor * blue + bias), 0), 255);

                result[x, y] = Color.FromArgb(r, g, b);
            }
        }
    }
    for (int i = 0; i < w; ++i)
    {
        for (int j = 0; j < h; ++j)
        {
            sharpenImage.SetPixel(i, j, result[i, j]);
        }
    }
    return sharpenImage;
}
于 2009-05-24T13:14:25.383 に答える
7

これにより、よりソフトなシャープ効果が得られます。必要に応じてフィルター配列を拡張したり、16 をより大きなものに変更したりできますが、これはあなたが持っているものほど厳しくないことがわかりました。

const int filterWidth = 5;
const int filterHeight = 5;

double[,] filter = new double[filterWidth,filterHeight] {
    { -1, -1, -1, -1, -1 },
    { -1,  2,  2,  2, -1 },
    { -1,  2,  16,  2, -1 },
    { -1,  2,  2,  2, -1 },
    { -1, -1, -1, -1, -1 }
};

double factor = 1.0 / 16.0;
于 2011-02-01T02:33:54.750 に答える
3

niaher と David の回答を組み合わせて、「バイアス」プロパティを修正しました。これで、0.0 から 1.0 までの「強さ」を Sharpen() 関数に渡すことができます。

/// <summary>
///     Sharpens the specified image.
/// </summary>
/// <param name="image">The image.</param>
/// <param name="strength">The strength between 0.0 and 1.0.</param>
/// <returns></returns>
public static Bitmap Sharpen(Image image, double strength)
{
    using (var bitmap = image as Bitmap)
    {
        if (bitmap != null)
        {
            var sharpenImage = bitmap.Clone() as Bitmap;

            int width = image.Width;
            int height = image.Height;

            // Create sharpening filter.
            const int filterWidth = 5;
            const int filterHeight = 5;

            var filter = new double[,]
                {
                    {-1, -1, -1, -1, -1},
                    {-1,  2,  2,  2, -1},
                    {-1,  2, 16,  2, -1},
                    {-1,  2,  2,  2, -1},
                    {-1, -1, -1, -1, -1}
                };

            double bias = 1.0 - strength;
            double factor = strength/16.0;

            var result = new Color[image.Width,image.Height];

            // Lock image bits for read/write.
            if (sharpenImage != null)
            {
                BitmapData pbits = sharpenImage.LockBits(new Rectangle(0, 0, width, height),
                                                            ImageLockMode.ReadWrite,
                                                            PixelFormat.Format24bppRgb);

                // Declare an array to hold the bytes of the bitmap.
                int bytes = pbits.Stride*height;
                var rgbValues = new byte[bytes];

                // Copy the RGB values into the array.
                Marshal.Copy(pbits.Scan0, rgbValues, 0, bytes);

                int rgb;
                // Fill the color array with the new sharpened color values.
                for (int x = 0; x < width; ++x)
                {
                    for (int y = 0; y < height; ++y)
                    {
                        double red = 0.0, green = 0.0, blue = 0.0;

                        for (int filterX = 0; filterX < filterWidth; filterX++)
                        {
                            for (int filterY = 0; filterY < filterHeight; filterY++)
                            {
                                int imageX = (x - filterWidth/2 + filterX + width)%width;
                                int imageY = (y - filterHeight/2 + filterY + height)%height;

                                rgb = imageY*pbits.Stride + 3*imageX;

                                red += rgbValues[rgb + 2]*filter[filterX, filterY];
                                green += rgbValues[rgb + 1]*filter[filterX, filterY];
                                blue += rgbValues[rgb + 0]*filter[filterX, filterY];
                            }

                            rgb = y*pbits.Stride + 3*x;

                            int r = Math.Min(Math.Max((int) (factor*red + (bias*rgbValues[rgb + 2])), 0), 255);
                            int g = Math.Min(Math.Max((int) (factor*green + (bias*rgbValues[rgb + 1])), 0), 255);
                            int b = Math.Min(Math.Max((int) (factor*blue + (bias*rgbValues[rgb + 0])), 0), 255);

                            result[x, y] = Color.FromArgb(r, g, b);
                        }
                    }
                }

                // Update the image with the sharpened pixels.
                for (int x = 0; x < width; ++x)
                {
                    for (int y = 0; y < height; ++y)
                    {
                        rgb = y*pbits.Stride + 3*x;

                        rgbValues[rgb + 2] = result[x, y].R;
                        rgbValues[rgb + 1] = result[x, y].G;
                        rgbValues[rgb + 0] = result[x, y].B;
                    }
                }

                // Copy the RGB values back to the bitmap.
                Marshal.Copy(rgbValues, 0, pbits.Scan0, bytes);
                // Release image bits.
                sharpenImage.UnlockBits(pbits);
            }

            return sharpenImage;
        }
    }
    return null;
}
于 2013-07-11T10:26:56.863 に答える