Java 8, 47.867 mudanças no total.
Usa a média da imagem como ponto central. Em seguida, atrai todos os raios possíveis para o centro e fornece o melhor raio para a cor. Em seguida, pinta todos os pontos inválidos em preto.
import javax.imageio.ImageIO;
import java.awt.Color;
import java.awt.image.BufferedImage;
import java.io.File;
import java.util.ArrayList;
import java.util.List;
public class MakeItStarry {
private static final int RGB_RED = Color.RED.getRGB();
static int[][] originalImage;
static final int WHITE = 0;
static final int BLACK = 1;
static final int RGB_WHITE = Color.WHITE.getRGB();
static final int RGB_BLACK = Color.BLACK.getRGB();
static final int RGB_BLUE = Color.BLUE.getRGB();
static final int RGB_YELLOW = Color.YELLOW.getRGB();
public static void main(String[] args) throws Exception{
originalImage = convert(ImageIO.read(new File(args[0])));
Point center = findCenter(originalImage);
int[][] nextImage = starry(originalImage, center);
BufferedImage result = difference(originalImage, nextImage);
result.setRGB(center.x, center.y, RGB_RED);
String fileType;
String fileName;
if (args[1].split("\\.").length > 1){
fileType = args[1].split("\\.")[1];
fileName = args[1];
} else {
fileType = "PNG";
fileName = args[1] + ".PNG";
}
ImageIO.write(result, fileType, new File(fileName));
System.out.println(cost);
}
static int cost;
private static BufferedImage difference(int[][] image1, int[][] image2) {
cost = 0;
int height = image1[0].length;
int width = image1.length;
BufferedImage result = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
for (int x = 0; x < width; x++){
for (int y = 0; y < width; y++){
if (image1[x][y] == image2[x][y]){
if (image1[x][y] == WHITE){
result.setRGB(x, y, RGB_WHITE);
} else {
result.setRGB(x, y, RGB_BLACK);
}
} else {
cost++;
if (image1[x][y] == WHITE){
result.setRGB(x, y, RGB_BLUE);
} else {
result.setRGB(x, y, RGB_YELLOW);
}
}
}
}
return result;
}
private static int[][] starry(int[][] image, Point center) {
int width = image.length;
int height = image[0].length;
int[][] result = new int[width][height];
for (int x = 0; x < width; x++){
for (int y = 0; y < height; y++){
result[x][y] = BLACK;
}
}
for (int x = 0; x < width; x++){
for (int y = 0; y < height; y++) {
Point endPoint = new Point(x, y, image);
List<Point> line = Point.lineTo(center, endPoint, image);
List<Point> newLine = starRay(line);
newLine.stream().filter(point -> result[point.x][point.y] == BLACK).forEach(point -> {
result[point.x][point.y] = point.color;
});
}
}
int distance = 0;
while (distance < height || distance < width){//This removes pixels that can't see the center.
for (int x = Math.max(center.x - distance,0); x < center.x + distance && x < width; x++){
for (int y = Math.max(center.y - distance, 0); y < center.y + distance && y < height; y++){
Point point = new Point(x, y, result);
if (Point.distance(center, point) != distance){
continue;
}
if (point.color == WHITE){
List<Point> line = Point.lineTo(center, point, result);
for (Point p : line){
if (p.color == BLACK){
point.color = BLACK;
break;
}
}
result[point.x][point.y] = point.color;
}
}
}//All white pixels can technically see the center but only if looking from the edge.
distance++;
}
return result;
}
private static List<Point> starRay(List<Point> line) {
int numOfWhites = 0;
int farthestGoodPoint = 0;
int blackCost = 0;
int whiteCost = 0;
for (int i = 0; i < line.size(); i++){
if (line.get(i).color == WHITE){
numOfWhites++;
whiteCost++;
if (numOfWhites + whiteCost > blackCost){
blackCost = 0;
whiteCost = 0;
farthestGoodPoint = i;
}
} else {
blackCost++;
numOfWhites = 0;
}
}
List<Point> result = new ArrayList<>();
for (int i = 0; i < line.size(); i++){
Point p = line.get(i);
if (i <= farthestGoodPoint){
result.add(new Point(p.x, p.y, WHITE));
} else {
result.add(new Point(p.x, p.y, BLACK));
}
}
return result;
}
private static Point findCenter(int[][] image) {
double totalx = 0;
double totaly = 0;
int counter = 0;
int width = image.length;
int height = image[0].length;
for (int x = 0; x < width; x++){
for (int y = 0; y < height; y++){
if (image[x][y] == WHITE){
totalx += x;
totaly += y;
counter++;
}
}
}
return new Point((int)(totalx/counter), (int)(totaly/counter), image);
}
private static int[][] convert(BufferedImage image) {
int width = image.getWidth();
int height = image.getHeight();
int[][] result = new int[width][height];
for (int x = 0; x < width; x++){
for (int y = 0; y < height; y++){
if (image.getRGB(x, y) == RGB_WHITE){
result[x][y] = WHITE;
} else {
result[x][y] = BLACK;
}
}
}
return result;
}
private static class Point {
public int color;
public int y;
public int x;
public Point(int x, int y, int[][] image) {
this.x = x;
this.y = y;
this.color = image[x][y];
}
public Point(int x, int y, int color) {
this.x = x;
this.y = y;
this.color = color;
}
public static List<Point> lineTo(Point point1, Point point2, int[][] image) {
List<Point> result = new ArrayList<>();
boolean reversed = false;
if (point1.x > point2.x){
Point buffer = point1;
point1 = point2;
point2 = buffer;
reversed = !reversed;
}
int rise = point1.y - point2.y;
int run = point1.x - point2.x;
if (run == 0){
if (point1.y > point2.y){
Point buffer = point1;
point1 = point2;
point2 = buffer;
reversed = !reversed;
}
int x = point1.x;
for (int y = point1.y; y <= point2.y; y++){
result.add(new Point(x, y, image));
}
if (reversed){
return reversed(result);
}
return result;
}
if (rise == 0){
if (point1.x > point2.x){
Point buffer = point1;
point1 = point2;
point2 = buffer;
reversed = !reversed;
}
int y = point1.y;
for (int x = point1.x; x <= point2.x; x++){
result.add(new Point(x, y, image));
}
if (reversed){
return reversed(result);
}
return result;
}
int gcd = gcd(rise, run);
rise /= gcd;
run /= gcd;
double slope = (rise + 0.0) / run;
if (Math.abs(rise) >= Math.abs(run)){
if (point1.y > point2.y){
Point buffer = point1;
point1 = point2;
point2 = buffer;
reversed = !reversed;
}
double x = point1.x;
for (double y = point1.y + .5; y <= point2.y; y++){
int px = (int) Math.round(x);
if (Math.abs(Math.abs(px - x) - .5) < Math.abs(1.0 / (rise * 4))){
x += 1/slope;
continue;
}
result.add(new Point(px, (int) Math.round(y - .5), image));
result.add(new Point(px, (int) Math.round(y + .5), image));
x += 1/slope;
}
if (reversed){
return reversed(result);
}
return result;
} else {
if (point1.x > point2.x){
Point buffer = point1;
point1 = point2;
point2 = buffer;
reversed = !reversed;
}
double y = point1.y;
for (double x = point1.x + .5; x <= point2.x; x++){
int py = (int) Math.round(y);
if (Math.abs(Math.abs(py - y) - .5) < Math.abs(1.0 / (run * 4))) {
y += slope;
continue;
}
result.add(new Point((int) Math.round(x - .5), py, image));
result.add(new Point((int) Math.round(x + .5), py, image));
y += slope;
}
if (reversed){
return reversed(result);
}
return result;
}
}
private static List<Point> reversed(List<Point> points) {
List<Point> result = new ArrayList<>();
for (int i = points.size() - 1; i >= 0; i--){
result.add(points.get(i));
}
return result;
}
private static int gcd(int num1, int num2) {
if (num1 < 0 && num2 < 0){
return -gcd(-num1, -num2);
}
if (num1 < 0){
return gcd(-num1, num2);
}
if (num2 < 0){
return gcd(num1, -num2);
}
if (num2 > num1){
return gcd(num2, num1);
}
if (num2 == 0){
return num1;
}
return gcd(num2, num1 % num2);
}
@Override
public String toString(){
return x + " " + y;
}
public static int distance(Point point1, Point point2) {
return Math.abs(point1.x - point2.x) + Math.abs(point1.y - point2.y);
}
}
}
Resultados
Imagem 1 - 0 alterações, Imagem 2 - 13.698 alterações
Imagem 3 - 24.269 alterações, Imagem 4 - 103 alterações
Imagem 5 - 5.344 alterações, Imagem 6 - 4.456 alterações
Sem pixels inválidos removidos, 42.782 alterações no total
Pixels verdes são a primeira camada de pixels inválidos.
Imagem 1 - 0 alterações, Imagem 2- 9.889 alterações
Imagem 3 - 24.268 alterações, Imagem 4 - 103 alterações
Imagem 5 - 4.471 alterações, Imagem 6- 4.050 alterações
Todos os pixels brancos em todas as imagens podem ter uma linha desenhada para eles a partir do pixel central, se a linha não precisar se originar / terminar nos centros, mas em qualquer lugar do pixel.
args[0] contém o nome do arquivo de entrada.
args[1] contém o nome do arquivo de saída.
Imprime para o stdoutnúmero de alterações.
