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How to get count of pixels red color on bitmap android

I want to get number of all red pixels on bitmap image, after I painted on it and merged with back image.
How can I do that? Please give me more details, I will be very grateful, thank you!
Example: Count of red pixels

Iterate through every single pixel in the bitmap
//define your red
static final int RED = Color.RED;
//counting
int count = 0;
for (int x = 0; x <= myBitmap.getWidth(); x++) {
for (int y = 0; x <= myBitmap.getHeight(); y++) {
if(myBitmap.getPixel(x, y))
count++;
}
}
//done. use the variable count

You have a Bitmap, you can get a pixel color from it using code below:
int countX = bitmap.getWidth();
int countY = bitmap.getHeight();
int redCount = 0;
for (int x = 0; x < countX; x++) {
for (int y = 0; y < countY; y--) {
int colorXY = bitmap.getPixel(x, y);
redCount += Color.red(colorXY);
}
}

I got something like this:
int countX = bm.getWidth();
int countY = bm.getHeight();
int redCount = 0;
for (int rangeX = 0; rangeX < countX; rangeX++) {
for (int rangeY = 0; rangeY < countY; rangeY++) {
int colorXY = bm.getPixel(rangeX, rangeY);
int r = Color.red(colorXY);
int g = Color.green(colorXY);
int b = Color.blue(colorXY);
if(Color.rgb(r,g,b) == Color.RED) {
redCount++;
/*bm.setPixel(rangeX,rangeY,Color.GREEN);*/
}
}
}

Exception in thread "AWT-EventQueue-0" java.lang.IllegalAccessError

I have a small game project where I have to use RMI to create a multiplayer game. I'm getting the following error:
Exception in thread "AWT-EventQueue-0" java.lang.IllegalAccessError: tried to
access class PlayArea from class com.sun.proxy.$Proxy1
at com.sun.proxy.$Proxy1.getPlayArea(Unknown Source)
at GameClient.getPlayArea(GameClient.java:100)
at PlayBoard.paintComponent(GUI.java:264)
Now those references are as follows:
Part of GameClient.java
public PlayArea getPlayArea() {
PlayArea result = null;
try {
result = myServer.getPlayArea(clientID); // line 100 of GameClient.java
} catch (Exception e) {
System.out.println("Error: " + e);
System.exit(1);
}
return result;
}
And this is part of GUI.java
public void paintComponent(Graphics g) {
PlayArea playArea = gui.getGameEngine().getPlayArea(); // line 264 of GUI.java
super.paintComponent(g);
LinkedList bricks = new LinkedList();
int pixCoeff = brickSize - 1;
for (int y = 0; y < bricksPerSide; y++) {
int pixY = y * pixCoeff;
for (int x = 0; x < bricksPerSide; x++) {
int brick = playArea.getBrick(x, y);
if (Colour.isBase(brick))
continue;
if (gui.displayMode == GUI.NOMARKED && Colour.isMarked(brick)) {
continue;
}
int pixX = x * pixCoeff;
bricks.add(new BoardBrick(pixX, pixY,
gui.displayMode == GUI.MARKEDASORIGINAL ? ColourMapper
.map(Colour.original(brick)) : (Colour
.isMarked(brick) ? Color.WHITE : ColourMapper
.map(brick))));
}
}
g.setColor(ColourMapper.map(Colour.BASE));
g.fillRect(0, 0, (brickSize - 1) * bricksPerSide + 1, (brickSize - 1)
* bricksPerSide + 1);
while (bricks.size() > 0) {
BoardBrick brick = (BoardBrick) (bricks.removeFirst());
brick.drawBrick(g);
}
if (gui.getGameEngine().isGameOver())
gameOver(g);
}
And this is PlayArea.java
import java.util.Random;
class PlayArea implements java.io.Serializable {
public static final int NORTHSIDE = 0;
public static final int SOUTHSIDE = 1;
public static final int EASTSIDE = 2;
public static final int WESTSIDE = 3;
private int[][] grid;
public PlayArea(int size) {
grid = new int[size][size];
}
public static int randomSide(Random rng) {
return rng.nextInt(4);
}
public int getSize() {
return grid.length;
}
public int getBrick(int x, int y) {
return grid[x][y];
}
public int getBrick(Coord c) {
return getBrick(c.getX(), c.getY());
}
public void setBrick(int x, int y, int val) {
grid[x][y] = val;
}
public void setBrick(Coord c, int val) {
setBrick(c.getX(), c.getY(), val);
}
// --> play_area_init_collision_flipDraw
public void init() {
int size = getSize();
for (int x = 0; x < size; x++)
for (int y = 0; y < size; y++)
if (x == 0 || y == 0 || x == size - 1 || y == size - 1)
setBrick(x, y, Colour.WALL);
else
setBrick(x, y, Colour.BASE);
setBrick(size / 2, size / 2, Colour.WALL);
setBrick(size / 2 - 2, size / 2 - 2, Colour.WALL);
setBrick(size / 2 - 2, size / 2 + 2, Colour.WALL);
setBrick(size / 2 + 2, size / 2 - 2, Colour.WALL);
setBrick(size / 2 + 2, size / 2 + 2, Colour.WALL);
}
public boolean collision(PlayingBlock block) {
int topLeftX = block.getPosition().getX();
int topLeftY = block.getPosition().getY();
int height = block.getHeight();
int length = block.getLength();
for (int x = 0; x < length; x++)
for (int y = 0; y < height; y++)
if (!Colour.isBase(getBrick(topLeftX + x, topLeftY + y)))
return true;
return false;
}
public void flipDraw(PlayingBlock block) {
int topLeftX = block.getPosition().getX();
int topLeftY = block.getPosition().getY();
int height = block.getHeight();
int length = block.getLength();
for (int x = 0; x < length; x++)
for (int y = 0; y < height; y++)
setBrick(topLeftX + x, topLeftY + y, getBrick(topLeftX + x,
topLeftY + y)
^ block.getColour());
}
// --<
// --> play_area_getSquareColour_mark
public int getSquareColour(int topLeftX, int topLeftY, int size) {
// return 0 if no square found
// square colour otherwise
if (topLeftX + size > getSize() || topLeftY + size > getSize())
return 0;
int colour = getBrick(topLeftX, topLeftY);
if (!Colour.isPlayBrick(colour))
return 0;
for (int x = topLeftX; x < topLeftX + size; x++)
for (int y = topLeftY; y < topLeftY + size; y++)
if (!Colour.isSameColour(colour, getBrick(x, y)))
return 0;
return colour;
}
public void mark(int topLeftX, int topLeftY, int size) {
for (int x = topLeftX; x < topLeftX + size; x++)
for (int y = topLeftY; y < topLeftY + size; y++)
setBrick(x, y, Colour.mark(getBrick(x, y)));
}
// --<
}
Now, what's weird is, this runs in Windows using Java 1.6, but on OS X it doesn't and I don't have access to a Windows machine right now. I'm using 1.6.0_65 on OS X 10.9.
I have found many errors on the web regarding AWT-EventQueue-0 but most of them are NullPointerException errors, not IllegalAccessError. I would appreciate any help, I'm quite new to Java.
UPDATE: The code most definitely works in 1.5 and 1.6. This is most likely related to the included libraries. I will keep looking and edit this post accordingly.

How can i find out where a BufferedImage has Alpha in Java?

I've got a BuferredImage and a boolean[][] array.
I want to set the array to true where the image is completely transparant.
Something like:
for(int x = 0; x < width; x++) {
for(int y = 0; y < height; y++) {
alphaArray[x][y] = bufferedImage.getAlpha(x, y) == 0;
}
}
But the getAlpha(x, y) method does not exist, and I did not find anything else I can use.
There is a getRGB(x, y) method, but I'm not sure if it contains the alpha value or how to extract it.
Can anyone help me?
Thank you!

public static boolean isAlpha(BufferedImage image, int x, int y)
{
return image.getRBG(x, y) & 0xFF000000 == 0xFF000000;
}
for(int x = 0; x < width; x++)
{
for(int y = 0; y < height; y++)
{
alphaArray[x][y] = isAlpha(bufferedImage, x, y);
}
}

Try this:
Raster raster = bufferedImage.getAlphaRaster();
if (raster != null) {
int[] alphaPixel = new int[raster.getNumBands()];
for (int x = 0; x < raster.getWidth(); x++) {
for (int y = 0; y < raster.getHeight(); y++) {
raster.getPixel(x, y, alphaPixel);
alphaArray[x][y] = alphaPixel[0] == 0x00;
}
}
}

public boolean isAlpha(BufferedImage image, int x, int y) {
Color pixel = new Color(image.getRGB(x, y), true);
return pixel.getAlpha() > 0; //or "== 255" if you prefer
}

What's wrong with this Java code for Android?

I have written this piece of code to break an image into 9 pieces and it gives me runtime error. There is no error in LogCat and I am stuck. The error comes at line 7 line from bottom (Bitmap.createBitmap(...);).
public Bitmap[] getPieces(Bitmap bmp) {
Bitmap[] bmps = new Bitmap[9];
int width = bmp.getWidth();
int height = bmp.getHeight();
int rows = 3;
int cols = 3;
int cellHeight = height / rows;
int cellWidth = width / cols;
int piece = 0;
for (int x = 0; x <= width; x += cellWidth) {
for (int y = 0; y <= height; y += cellHeight) {
Bitmap b = Bitmap.createBitmap(bmp, x, y, cellWidth,
cellHeight, null, false);
bmps[piece] = b;
piece++;
}
}
return bmps;
}

It is a limitation of android framework which doesn't give proper error message. The ideal solution would be to wrap your code in try / catch block and log the exception to console and fix your code accordingly, but use it only for debugging purposes.
try {
// Code
}
catch (Exception e) {
Log.e("ERROR", "ERROR IN CODE:"+e.toString());
}
The above code extracted from here:
http://moazzam-khan.com/blog/?p=41

Instead of
for (int x = 0; x <= width; x += cellWidth) {
for (int y = 0; y <= height; y += cellHeight) {
use
for (int x = 0; x+cellWidth < width; x += cellWidth) {
for (int y = 0; y+cellHeight < height; y += cellHeight) {
to avoid fetching parts of the image that (at least partly) don't exist.

In your code, piece can be greater than 8, so you are getting index out of bounds on bmps. You need to rewrite it so that the right-most and bottom-most pieces just have all of the extra and aren't necessarily the same size.
Or, if you need them to be the same size, drop the extra rows/cols. To make sure, I would formulate my for loop like this
for (int cellX = 0; cellX < 3; cellX++) {
int x = cellX * cellWidth;
for (int cellY = 0; cellY < 3; cellY++) {
int y = cellY * cellHeight;
// find the cellWidth/Height that doesn't overflow the original image
Bitmap b = // get the bitmap
bmps[piece] = b;
piece++;
}
}

Crop image to smallest size by removing transparent pixels in java

I have a sprite sheet which has each image centered in a 32x32 cell. The actual images are not 32x32, but slightly smaller. What I'd like to do is take a cell and crop the transparent pixels so the image is as small as it can be.
How would I do that in Java (JDK 6)?
Here is an example of how I'm currently breaking up the tile sheet into cells:
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..
}
My current idea was to test each pixel from the center working my way out to see if it is transparent, but I was wondering if there would be a faster/cleaner way of doing this.

There's a trivial solution – to scan every pixel. The algorithm bellow has a constant performance of O(w•h).
private static BufferedImage trimImage(BufferedImage image) {
int width = image.getWidth();
int height = image.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 (image.getRGB(x, y) != 0){
top = Math.min(top, y);
bottom = Math.max(bottom, y);
left = Math.min(left, x);
right = Math.max(right, x);
}
}
}
return image.getSubimage(left, top, right - left + 1, bottom - top + 1);
}
But this is much more effective:
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);
}
This algorithm follows the idea from pepan's answer (see above) and is 2 to 4 times more effective. The difference is: it never scans any pixel twice and tries to contract search range on each stage.
The worst case of the method's performance is O(w•h–a•b)

This code works for me. The algorithm is simple, it iterates from left/top/right/bottom of the picture and finds the very first pixel in the column/row which is not transparent. It then remembers the new corner of the trimmed picture and finally it returns the sub image of the original image.
There are things which could be improved.
The algorithm expects, there is the alpha byte in the data. It will fail on an index out of array exception if there is not.
The algorithm expects, there is at least one non-transparent pixel in the picture. It will fail if the picture is completely transparent.
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);
}

I think this is exactly what you should do, loop through the array of pixels, check for alpha and then discard. Although when you for example would have a star shape it will not resize the image to be smaller be aware of this.

A simple fix for code above. I used the median for RGB and fixed the min() function of x and y:
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;
}

[Hi I tried the following. In the images file idle1.png is the image with a big transparent box while testing.png is the same image with minimum bounding box
'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));
where the get functions are
public int getY1(WritableRaster raster) {
//top of character
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]
Thank you for your help regards Michael.Look at Idle1.png and the minimum bounding box idle = testing.png]images here

If your sheet already has transparent pixels, the BufferedImage returned by getSubimage() will, too. The default Graphics2D composite rule is AlphaComposite.SRC_OVER, which should suffice for drawImage().
If the sub-images have a distinct background color, use a LookupOp with a four-component LookupTable that sets the alpha component to zero for colors that match the background.
I'd traverse the pixel raster only as a last resort.
Addendum: Extra transparent pixels may interfere with collision detection, etc. Cropping them will require working with a WritableRaster directly. Rather than working from the center out, I'd start with the borders, using a pair of getPixels()/setPixels() methods that can modify a row or column at a time. If a whole row or column has zero alpha, mark it for elimination when you later get a sub-image.