在java中通过删除透明像素将图像裁剪为最小大小
我有一张sprite表,每张图像都集中在一个32x32的单元格中。实际图像不是32x32,而是稍小一些。我想做的是取一个细胞,裁剪透明像素,使图像尽可能小 在Java(JDK 6)中我将如何做到这一点 下面是一个示例,说明我当前如何将平铺表拆分为单元格:在java中通过删除透明像素将图像裁剪为最小大小,java,image,image-processing,crop,Java,Image,Image Processing,Crop,我有一张sprite表,每张图像都集中在一个32x32的单元格中。实际图像不是32x32,而是稍小一些。我想做的是取一个细胞,裁剪透明像素,使图像尽可能小 在Java(JDK 6)中我将如何做到这一点 下面是一个示例,说明我当前如何将平铺表拆分为单元格: BufferedImage tilesheet = ImageIO.read(getClass().getResourceAsStream("/sheet.png"); for (int i = 0; i < 15; i++) { I
BufferedImage tilesheet = ImageIO.read(getClass().getResourceAsStream("/sheet.png");
for (int i = 0; i < 15; i++) {
Image img = tilesheet.getSubimage(i * 32, 0, 32, 32);
// crop here..
}
buffereImage tilesheet=ImageIO.read(getClass().getResourceAsStream(“/sheet.png”);
对于(int i=0;i<15;i++){
Image img=tilesheet.getSubimage(i*32,0,32,32);
//在这里收成。。
}
我目前的想法是从中心开始测试每个像素,看看它是否透明,但我想知道是否有更快/更干净的方法。我认为这正是你应该做的,在像素阵列中循环,检查alpha,然后丢弃。尽管例如,当你有一个星号时pe它不会将图像大小调整为更小。请注意这一点。如果您的工作表已经有透明像素,则
getSubimage()
返回的buffereImage
也将如此。默认的Graphics2D
是AlphaComposite.SRC\u OVER
,它应该满足drawImage()
的要求
如果子图像具有不同的背景颜色,请使用带有四分量LookupTable
的,将alpha分量设置为零以匹配背景的颜色
我只能在万不得已的情况下遍历像素光栅
补充:超透明像素可能会干扰碰撞检测等。裁剪它们需要直接使用a。与其从中间开始,我会从边框开始,使用一对
getPixels()
/setPixels()
可以一次修改一行或一列的方法。如果整行或整列的alpha为零,请在以后获得子图像时将其标记为消除。此代码适用于我。算法很简单,它从图片的左/上/右/下迭代,并在列/行中找到第一个不透明的像素。然后,它将e记住修剪图片的新角点,最后返回原始图像的子图像
有些事情是可以改进的
private static BufferedImage trimImage(BufferedImage img) {
final byte[] pixels = ((DataBufferByte) img.getRaster().getDataBuffer()).getData();
int width = img.getWidth();
int height = img.getHeight();
int x0, y0, x1, y1; // the new corners of the trimmed image
int i, j; // i - horizontal iterator; j - vertical iterator
leftLoop:
for (i = 0; i < width; i++) {
for (j = 0; j < height; j++) {
if (pixels[(j*width+i)*4] != 0) { // alpha is the very first byte and then every fourth one
break leftLoop;
}
}
}
x0 = i;
topLoop:
for (j = 0; j < height; j++) {
for (i = 0; i < width; i++) {
if (pixels[(j*width+i)*4] != 0) {
break topLoop;
}
}
}
y0 = j;
rightLoop:
for (i = width-1; i >= 0; i--) {
for (j = 0; j < height; j++) {
if (pixels[(j*width+i)*4] != 0) {
break rightLoop;
}
}
}
x1 = i+1;
bottomLoop:
for (j = height-1; j >= 0; j--) {
for (i = 0; i < width; i++) {
if (pixels[(j*width+i)*4] != 0) {
break bottomLoop;
}
}
}
y1 = j+1;
return img.getSubimage(x0, y0, x1-x0, y1-y0);
专用静态BuffereImage trimImage(BuffereImage img){
最终字节[]像素=((DataBufferByte)img.getRaster().getDataBuffer()).getData();
int width=img.getWidth();
int height=img.getHeight();
int x0,y0,x1,y1;//修剪图像的新角点
int i,j;//i-水平迭代器;j-垂直迭代器
左循环:
对于(i=0;i=0;i--){
对于(j=0;j=0;j--){
对于(i=0;i
}O(w•h)
专用静态BuffereImage trimImage(BuffereImage图像){
int width=image.getWidth();
int height=image.getHeight();
int top=高度/2;
int底部=顶部;
int left=宽度/2;
int right=left;
对于(int x=0;x
但这要有效得多:
private static BufferedImage trimImage(BufferedImage image) {
WritableRaster raster = image.getAlphaRaster();
int width = raster.getWidth();
int height = raster.getHeight();
int left = 0;
int top = 0;
int right = width - 1;
int bottom = height - 1;
int minRight = width - 1;
int minBottom = height - 1;
top:
for (;top < bottom; top++){
for (int x = 0; x < width; x++){
if (raster.getSample(x, top, 0) != 0){
minRight = x;
minBottom = top;
break top;
}
}
}
left:
for (;left < minRight; left++){
for (int y = height - 1; y > top; y--){
if (raster.getSample(left, y, 0) != 0){
minBottom = y;
break left;
}
}
}
bottom:
for (;bottom > minBottom; bottom--){
for (int x = width - 1; x >= left; x--){
if (raster.getSample(x, bottom, 0) != 0){
minRight = x;
break bottom;
}
}
}
right:
for (;right > minRight; right--){
for (int y = bottom; y >= top; y--){
if (raster.getSample(right, y, 0) != 0){
break right;
}
}
}
return image.getSubimage(left, top, right - left + 1, bottom - top + 1);
}
专用静态BuffereImage trimImage(BuffereImage图像){
WritableRaster raster=image.getAlphaRaster();
int width=graster.getWidth();
int height=graster.getHeight();
int左=0;
int-top=0;
int right=宽度-1;
内底=高度-1;
int minRight=宽度-1;
int minBottom=高度-1;
顶部:
用于(;顶部<底部;顶部++){
对于(int x=0;x顶部;y--){
if(光栅.getSample(左,y,0)!=0){
minBottom=y;
向左转;
}
}
}
底部:
对于(;底部>最小底部;底部--){
对于(int x=width-1;x>=left;x--){
if(graster.getSample(x,底部,0)!=0){
minRight=x;
打破谷底;
}
}
}
正确的:
对于(;right>minRight;right--){
对于(int y=底部;y>=顶部;y--){
if(光栅.getSample(右,y,0)!=0){
右转;
}
}
}
返回image.getSubimage(左、上、右-le
private static BufferedImage trimImage(BufferedImage image) {
WritableRaster raster = image.getAlphaRaster();
int width = raster.getWidth();
int height = raster.getHeight();
int left = 0;
int top = 0;
int right = width - 1;
int bottom = height - 1;
int minRight = width - 1;
int minBottom = height - 1;
top:
for (;top < bottom; top++){
for (int x = 0; x < width; x++){
if (raster.getSample(x, top, 0) != 0){
minRight = x;
minBottom = top;
break top;
}
}
}
left:
for (;left < minRight; left++){
for (int y = height - 1; y > top; y--){
if (raster.getSample(left, y, 0) != 0){
minBottom = y;
break left;
}
}
}
bottom:
for (;bottom > minBottom; bottom--){
for (int x = width - 1; x >= left; x--){
if (raster.getSample(x, bottom, 0) != 0){
minRight = x;
break bottom;
}
}
}
right:
for (;right > minRight; right--){
for (int y = bottom; y >= top; y--){
if (raster.getSample(right, y, 0) != 0){
break right;
}
}
}
return image.getSubimage(left, top, right - left + 1, bottom - top + 1);
}
private static BufferedImage trim(BufferedImage img) {
int width = img.getWidth();
int height = img.getHeight();
int top = height / 2;
int bottom = top;
int left = width / 2 ;
int right = left;
for (int x = 0; x < width; x++) {
for (int y = 0; y < height; y++) {
if (isFg(img.getRGB(x, y))){
top = Math.min(top, y);
bottom = Math.max(bottom, y);
left = Math.min(left, x);
right = Math.max(right, x);
}
}
}
return img.getSubimage(left, top, right - left, bottom - top);
}
private static boolean isFg(int v) {
Color c = new Color(v);
return(isColor((c.getRed() + c.getGreen() + c.getBlue())/2));
}
private static boolean isColor(int c) {
return c > 0 && c < 255;
}
'BufferedImage tempImg = (ImageIO.read(new File(fileNPath)));
WritableRaster tempRaster = tempImg.getAlphaRaster();
int x1 = getX1(tempRaster);
int y1 = getY1(tempRaster);
int x2 = getX2(tempRaster);
int y2 = getY2(tempRaster);
System.out.println("x1:"+x1+" y1:"+y1+" x2:"+x2+" y2:"+y2);
BufferedImage temp = tempImg.getSubimage(x1, y1, x2 - x1, y2 - y1);
//for idle1.png
String filePath = fileChooser.getCurrentDirectory() + "\\"+"testing.png";
System.out.println("filePath:"+filePath);
ImageIO.write(temp,"png",new File(filePath));
for (int y = 0; y < raster.getHeight(); y++) {
for (int x = 0; x < raster.getWidth(); x++) {
if (raster.getSample(x, y,0) != 0) {
if(y>0) {
return y - 1;
}else{
return y;
}
}
}
}
return 0;
}
public int getY2(WritableRaster raster) {
//ground plane of character
for (int y = raster.getHeight()-1; y > 0; y--) {
for (int x = 0; x < raster.getWidth(); x++) {
if (raster.getSample(x, y,0) != 0) {
return y + 1;
}
}
}
return 0;
}
public int getX1(WritableRaster raster) {
//left side of character
for (int x = 0; x < raster.getWidth(); x++) {
for (int y = 0; y < raster.getHeight(); y++) {
if (raster.getSample(x, y,0) != 0) {
if(x > 0){
return x - 1;
}else{
return x;
}
}
}
}
return 0;
}
public int getX2(WritableRaster raster) {
//right side of character
for (int x = raster.getWidth()-1; x > 0; x--) {
for (int y = 0; y < raster.getHeight(); y++) {
if (raster.getSample(x, y,0) != 0) {
return x + 1;
}
}
}
return 0;
}'[Look at Idle1.png and the minimum bounding box idle = testing.png][1]