// Use the minimum brightness value in a region.
public Bitmap32 RankMinimum(int rank, bool lock_result)
{
// Make a copy of this Bitmap32.
Bitmap32 result = this.Clone();
// Lock both bitmaps.
bool was_locked = this.IsLocked;
this.LockBitmap();
result.LockBitmap();
// Calculate bounds to iterate over.
int start_i = -rank / 2;
int stop_i = rank + start_i;
for (int y = 0; y < Height; y++)
{
for (int x = 0; x < Width; x++)
{
// Find the brightest pixel around this one.
int best_brightness = GetRed(x, y) + GetGreen(x, y) + GetBlue(x, y);
int best_row = y;
int best_col = x;
for (int dy = start_i; dy < stop_i; dy++)
{
int row = y + dy;
if ((row >= 0) && (row < Height))
{
for (int dx = start_i; dx < stop_i; dx++)
{
int col = x + dx;
if ((col >= 0) && (col < Width))
{
int test_brightness =
GetRed(col, row) +
GetGreen(col, row) +
GetBlue(col, row);
if (test_brightness < best_brightness)
{
best_brightness = test_brightness;
best_row = row;
best_col = col;
}
}
}
}
}
// Set this pixel to the brighest value we found.
result.SetPixel(x, y,
GetRed(best_col, best_row),
GetGreen(best_col, best_row),
GetBlue(best_col, best_row),
255);
}
}
// Unlock the bitmaps.
if (!lock_result)
{
result.UnlockBitmap();
}
if (!was_locked)
{
this.UnlockBitmap();
}
// Return the result.
return(result);
}
// Apply a filter to the image.
public Bitmap32 ApplyFilter(Filter filter, bool lock_result)
{
// Make a copy of this Bitmap32.
Bitmap32 result = this.Clone();
// Lock both bitmaps.
bool was_locked = this.IsLocked;
this.LockBitmap();
result.LockBitmap();
// Apply the filter.
int xoffset = -(int)(filter.Kernel.GetUpperBound(1) / 2);
int yoffset = -(int)(filter.Kernel.GetUpperBound(0) / 2);
int xmin = -xoffset;
int xmax = Bitmap.Width - filter.Kernel.GetUpperBound(1);
int ymin = -yoffset;
int ymax = Bitmap.Height - filter.Kernel.GetUpperBound(0);
int row_max = filter.Kernel.GetUpperBound(0);
int col_max = filter.Kernel.GetUpperBound(1);
for (int x = xmin; x <= xmax; x++)
{
for (int y = ymin; y <= ymax; y++)
{
// Skip the pixel if any under the kernel
// is completely transparent.
bool skip_pixel = false;
// Apply the filter to pixel (x, y).
float red = 0, green = 0, blue = 0;
for (int row = 0; row <= row_max; row++)
{
for (int col = 0; col <= col_max; col++)
{
int ix = x + col + xoffset;
int iy = y + row + yoffset;
byte new_red, new_green, new_blue, new_alpha;
this.GetPixel(ix, iy, out new_red, out new_green, out new_blue, out new_alpha);
// See if we should skip this pixel.
if (new_alpha == 0)
{
skip_pixel = true;
break;
}
red += new_red * filter.Kernel[row, col];
green += new_green * filter.Kernel[row, col];
blue += new_blue * filter.Kernel[row, col];
}
if (skip_pixel)
{
break;
}
}
if (!skip_pixel)
{
// Divide by the weight, add the offset, and
// make sure the result is between 0 and 255.
red = filter.Offset + red / filter.Weight;
if (red < 0)
{
red = 0;
}
if (red > 255)
{
red = 255;
}
green = filter.Offset + green / filter.Weight;
if (green < 0)
{
green = 0;
}
if (green > 255)
{
green = 255;
}
blue = filter.Offset + blue / filter.Weight;
if (blue < 0)
{
blue = 0;
}
if (blue > 255)
{
blue = 255;
}
// Set the new pixel's value.
result.SetPixel(x, y, (byte)red, (byte)green, (byte)blue,
this.GetAlpha(x, y));
}
}
}
// Unlock the bitmaps.
if (!lock_result)
{
result.UnlockBitmap();
}
if (!was_locked)
{
this.UnlockBitmap();
}
// Return the result.
return(result);
}