public static Bitmap FilterSharpen7(Bitmap image)
{
ConMatrix matr = new ConMatrix();
matr.Size = 7;
matr.Matrix = new int[7, 7]
{
{ 0, 0, 0, -2, -2, 0, 0 },
{ 0, 0, 0, -2, -2, 0, 0 },
{ -2, -2, 0, -2, 0, 0, 0 },
{ -2, -2, -2, 11, -2, -2, -2 },
{ 0, 0, 0, -2, 0, -2, -2 },
{ 0, 0, -2, -2, 0, 0, 0 },
{ 0, 0, -2, -2, 0, 0, 0 }
};
return(Sharpen.ImgConvolution(image, matr));
}
private static Bitmap ImgConvolution(Bitmap image, ConMatrix fmat)
{
//Avoid division by 0
if (fmat.Factor == 0)
{
return(null);
}
Bitmap srcImage = (Bitmap)image.Clone();
int x, y, filterx, filtery, tempx, tempy;
int s = fmat.Size / 2;
int r, g, b, tr, tg, tb;
int pixelSize = GetPixelSize(image);
BitmapData imageData = image.LockBits(new Rectangle(0, 0, image.Width, image.Height), ImageLockMode.WriteOnly, image.PixelFormat);
BitmapData srcImageData = srcImage.LockBits(new Rectangle(0, 0, image.Width, image.Height), ImageLockMode.ReadOnly, image.PixelFormat);
// Scan0 is the memory address where pixel-array begins.
// Stride is the width of each row of pixels.
int stride = srcImageData.Stride;
IntPtr scan0 = srcImageData.Scan0;
unsafe
{
byte *tempPixel;
for (y = s; y < srcImageData.Height - s; y++)
{
for (x = s; x < srcImageData.Width - s; x++)
{
r = g = b = 0;
//Convolution
for (filtery = 0; filtery < fmat.Size; filtery++)
{
for (filterx = 0; filterx < fmat.Size; filterx++)
{
// Get nearby pixel's position
tempx = x + filterx - s;
tempy = y + filtery - s;
// Go to that pixel in pixel-array
tempPixel = (byte *)scan0 + (tempy * stride) + (tempx * pixelSize);
// The format is BGRA (1 byte each). Get em
tb = (int)*tempPixel;
tg = (int)*(tempPixel + 1);
tr = (int)*(tempPixel + 2);
r += fmat.Matrix[filtery, filterx] * tr;
g += fmat.Matrix[filtery, filterx] * tg;
b += fmat.Matrix[filtery, filterx] * tb;
}
}
// Remove values out of [0,255]
r = Math.Min(Math.Max((r / fmat.Factor) + fmat.Offset, 0), 255);
g = Math.Min(Math.Max((g / fmat.Factor) + fmat.Offset, 0), 255);
b = Math.Min(Math.Max((b / fmat.Factor) + fmat.Offset, 0), 255);
// Compute new pixel position (in new image) and write the pixels (BGRA format)
byte *newpixel = (byte *)imageData.Scan0 + (y * imageData.Stride) + (x * pixelSize);
* newpixel = (byte)b;
*(newpixel + 1) = (byte)g;
*(newpixel + 2) = (byte)r;
// If there is Alpha value
if (HasAlpha(image))
{
*(newpixel + 3) = 255;
}
}
}
}
image.UnlockBits(imageData);
srcImage.UnlockBits(srcImageData);
return(image);
}
