/**
For each pixel location in the new buffer P' (NewX, NewY), do:
Find corresponding old location, P = W-1.P'
Validate that this old location lie inside the original image boundary (i.e. 0 ≤ OldX < W, 0 ≤ Old Y < H). Otherwise, set the new empty pixel to 0 and continue to next location.
If Validated, apply Bilinear Interpolation Algorithm to get the new pixel value, as follows:(Refer to above figure)
*/
public BufferedImage apply_transformation_matrix_to_bitmap_or_buffer(Matrix _transformations_matrix, BufferedImage _src_img, int _new_width, int _new_height, TextBox _console)
{
BufferedImage ret = new BufferedImage(_new_width, _new_height);
BilinearInterpolation obj_bi_lin_interpol = new BilinearInterpolation();
for (int i = 0; i < _new_width; i++)
{
for (int j = 0; j < _new_height; j++)
{
PointF[] points = {
new PointF(i, j)
};
_transformations_matrix.TransformPoints(points);
_console.Text += "P = (" + points[0].X + ", " + points[0].Y + ")";
_console.Text += Environment.NewLine;
_console.Text += "P' = (" + i + ", " + j + ")";
_console.Text += Environment.NewLine;
Color _color = Color.FromArgb(0);
if(points[0].X >= 0 && points[0].X < _src_img.width && points[0].Y >= 0 && points[0].Y < _src_img.height)
_color = obj_bi_lin_interpol.calculate(_src_img, points[0].X, points[0].Y);
ret.buffer[i, j] = _color;
}
}
return ret;
}
public void run_test(TextBox _console)
{
Bitmap bmp = new Bitmap(Image.FromFile("C:/lenna.png"));
BufferedImage obj_buff_img = new BufferedImage(bmp, _console);
ImageMatrixTransformations obj_trans = new ImageMatrixTransformations();
BufferedImage ret = obj_trans.perform_concat_matrices_operations(obj_buff_img, _console);
Bitmap new_bmp = ret.get_bitmap_object();
new_bmp.Save("new_lenna.png");
}
/**
* find 4 adjacent pixels
X1 = floor (OldX) ; X2 = X1 + 1
Y1 = floor (OldY) ; Y2 = Y1 + 1
P1 = OrigBuf[X1,Y1] ; P2 = OrigBuf[X2,Y1]
P3 = OrigBuf[X1,Y2] ; P4 = OrigBuf[X2,Y2]
Calculate X, Y fractions
Xfraction = OldX – X1
Yfraction = OldY – Y1
Interpolate in X-Direction
Z1 = P1 × (1 – Xfraction) + P2 × Xfraction
Z2 = P3 × (1 – Xfraction) + P4 × Xfraction
Interpolate in Y-Direction
NewPixel = Z1 × (1 – Yfraction) + Z2 × Yfraction
*/
public Color calculate(BufferedImage _original_buffer, float _old_x, float _old_y)
{
int new_red, new_green, new_blue;
Color ret;
int x_1 = (int)Math.Floor(_old_x);
int x_2 = x_1 + 1;
int y_1 = (int)Math.Floor(_old_y);
int y_2 = y_1 + 1;
Color p_1 = _original_buffer.buffer[x_1, y_1];
Color p_2 = _original_buffer.buffer[x_2, y_2];
Color p_3 = _original_buffer.buffer[x_1, y_2];
Color p_4 = _original_buffer.buffer[x_2, y_2];
float x_fraction = _old_x - x_1;
float y_fraction = _old_y - y_1;
// Interpolate in X-Direction
// Red
int r_1 = (int)Math.Floor(p_1.R * (1 - x_fraction) + p_2.R * x_fraction);
int r_2 = (int)Math.Floor(p_3.R * (1 - x_fraction) + p_4.R * x_fraction);
// Green
int g_1 = (int)Math.Floor(p_1.G * (1 - x_fraction) + p_2.G * x_fraction);
int g_2 = (int)Math.Floor(p_3.G * (1 - x_fraction) + p_4.G * x_fraction);
// Blue
int b_1 = (int)Math.Floor(p_1.B * (1 - x_fraction) + p_2.B * x_fraction);
int b_2 = (int)Math.Floor(p_3.B * (1 - x_fraction) + p_4.B * x_fraction);
// Interpolate in Y-Direction
new_red = (int)Math.Floor(r_1 * (1 - y_fraction) + r_2 * y_fraction);
new_green = (int)Math.Floor(g_1 * (1 - y_fraction) + g_2 * y_fraction);
new_blue = (int)Math.Floor(b_1 * (1 - y_fraction) + b_2 * y_fraction);
ret = Color.FromArgb(new_red, new_green, new_blue);
return ret;
}
/**
You can use this matrix as follows:
1 - Create new object with identity matrix (empty constructor)
2 - Apply a set of transformations that you want to this matrix
3 - Transform the four corners of the original image to calculate
4 - The min X and min Y of the transformed image
5 - The width & height of the new image buffer
6 - Translate this matrix by (- min X, - min Y)
7 - Invert the matrix
8 - Use the inverted version to reverse transform all new locations in the new image buffer
**/
public BufferedImage perform_concat_matrices_operations(BufferedImage _src_img, TextBox _console, float _shear_x = (float)0, float _shear_y = (float)0, float _scale_x = (float)1, float _scale_y = (float)1, float _rotate_theta = (float)0)
{
BufferedImage ret;
// 1 - Create new object with identity matrix (empty constructor)
Matrix transformations_matrix = new Matrix();
// 2 - Apply a set of transformations that you want to this matrix
transformations_matrix.Rotate(_rotate_theta);
transformations_matrix.Scale(_scale_x, _scale_y);
transformations_matrix.Shear(_shear_x, _shear_y);
// 3 - Transform the four corners of the original image to calculate
/**
* To get the size of the new (destination) image,
* apply the forward mapping to the four corners of the original image
* ([0,0], [W-1,0], [0,H-1], [W-1,H-1])
* to get their new locations.
* Then use these new four locations to get the width and height of the destination image
* (e.g. to get new width:
* find min X & max X of the four new points and subtract them,
* do the same for Y to get the new height)
*/
Point[] corner_points = {
new Point(0, 0),
new Point(_src_img.width - 1, 0),
new Point(0, _src_img.height - 1),
new Point(_src_img.width - 1, _src_img.height - 1)
};
transformations_matrix.TransformPoints(corner_points);
int min_x = find_min_x(corner_points);
int min_y = find_min_y(corner_points);
int max_x = find_max_x(corner_points);
int max_y = find_max_y(corner_points);
int new_width = max_x - min_x;
int new_height = max_y - min_y;
_console.Text += "Min X = ";
_console.Text += min_x;
_console.Text += Environment.NewLine;
_console.Text += "Min Y = ";
_console.Text += min_y;
_console.Text += Environment.NewLine;
_console.Text += "Max X = ";
_console.Text += max_x;
_console.Text += Environment.NewLine;
_console.Text += "Max Y = ";
_console.Text += max_y;
_console.Text += Environment.NewLine;
_console.Text += "New Width = ";
_console.Text += new_width;
_console.Text += Environment.NewLine;
_console.Text += "New Height = ";
_console.Text += new_height;
_console.Text += Environment.NewLine;
// 4 - The min X and min Y of the transformed image
/**
* To make the transformed image totally fit inside the buffer, a translation with (- min X, - min Y) should be appended to the original transformation matrix (W) before inverting it.
*/
// 6 - Translate this matrix by (- min X, - min Y)
transformations_matrix.Translate(-min_x, -min_y);
// 7 - Invert the matrix
transformations_matrix.Invert();
// 8 - Use the inverted version to reverse transform all new locations in the new image buffer
ret = apply_transformation_matrix_to_bitmap_or_buffer(transformations_matrix, _src_img, new_width, new_height, _console);
return ret;
}
