Develop Reference

How To Convert a Image to a BufferedImage without loosing a GIFs animation [duplicate]

I want to be able to take an animated GIF as input, count the frames (and perhaps other metadata), and convert each to a BufferedImage.
How can I do this?

If you want all the frames to be the same size (for optimized GIFs) try something like this:
try {
String[] imageatt = new String[]{
"imageLeftPosition",
"imageTopPosition",
"imageWidth",
"imageHeight"
};
ImageReader reader = (ImageReader)ImageIO.getImageReadersByFormatName("gif").next();
ImageInputStream ciis = ImageIO.createImageInputStream(new File("house2.gif"));
reader.setInput(ciis, false);
int noi = reader.getNumImages(true);
BufferedImage master = null;
for (int i = 0; i < noi; i++) {
BufferedImage image = reader.read(i);
IIOMetadata metadata = reader.getImageMetadata(i);
Node tree = metadata.getAsTree("javax_imageio_gif_image_1.0");
NodeList children = tree.getChildNodes();
for (int j = 0; j < children.getLength(); j++) {
Node nodeItem = children.item(j);
if(nodeItem.getNodeName().equals("ImageDescriptor")){
Map<String, Integer> imageAttr = new HashMap<String, Integer>();
for (int k = 0; k < imageatt.length; k++) {
NamedNodeMap attr = nodeItem.getAttributes();
Node attnode = attr.getNamedItem(imageatt[k]);
imageAttr.put(imageatt[k], Integer.valueOf(attnode.getNodeValue()));
}
if(i==0){
master = new BufferedImage(imageAttr.get("imageWidth"), imageAttr.get("imageHeight"), BufferedImage.TYPE_INT_ARGB);
}
master.getGraphics().drawImage(image, imageAttr.get("imageLeftPosition"), imageAttr.get("imageTopPosition"), null);
}
}
ImageIO.write(master, "GIF", new File( i + ".gif"));
}
} catch (IOException e) {
e.printStackTrace();
}

None of the answers here are correct and suitable for animation. There are many problems in each solution so I wrote something that actually works with all gif files. For instance, this takes into account the actual width and height of the image instead of taking the width and height of the first frame assuming it will fill the entire canvas, no, unfortunately it's not that simple. Second, this doesn't leave any transparent pickles. Third, this takes into account disposal Methods. Fourth, this gives you delays between frames (* 10 if you want to use it in Thread.sleep()).
private ImageFrame[] readGif(InputStream stream) throws IOException{
ArrayList<ImageFrame> frames = new ArrayList<ImageFrame>(2);
ImageReader reader = (ImageReader) ImageIO.getImageReadersByFormatName("gif").next();
reader.setInput(ImageIO.createImageInputStream(stream));
int lastx = 0;
int lasty = 0;
int width = -1;
int height = -1;
IIOMetadata metadata = reader.getStreamMetadata();
Color backgroundColor = null;
if(metadata != null) {
IIOMetadataNode globalRoot = (IIOMetadataNode) metadata.getAsTree(metadata.getNativeMetadataFormatName());
NodeList globalColorTable = globalRoot.getElementsByTagName("GlobalColorTable");
NodeList globalScreeDescriptor = globalRoot.getElementsByTagName("LogicalScreenDescriptor");
if (globalScreeDescriptor != null && globalScreeDescriptor.getLength() > 0){
IIOMetadataNode screenDescriptor = (IIOMetadataNode) globalScreeDescriptor.item(0);
if (screenDescriptor != null){
width = Integer.parseInt(screenDescriptor.getAttribute("logicalScreenWidth"));
height = Integer.parseInt(screenDescriptor.getAttribute("logicalScreenHeight"));
}
}
if (globalColorTable != null && globalColorTable.getLength() > 0){
IIOMetadataNode colorTable = (IIOMetadataNode) globalColorTable.item(0);
if (colorTable != null) {
String bgIndex = colorTable.getAttribute("backgroundColorIndex");
IIOMetadataNode colorEntry = (IIOMetadataNode) colorTable.getFirstChild();
while (colorEntry != null) {
if (colorEntry.getAttribute("index").equals(bgIndex)) {
int red = Integer.parseInt(colorEntry.getAttribute("red"));
int green = Integer.parseInt(colorEntry.getAttribute("green"));
int blue = Integer.parseInt(colorEntry.getAttribute("blue"));
backgroundColor = new Color(red, green, blue);
break;
}
colorEntry = (IIOMetadataNode) colorEntry.getNextSibling();
}
}
}
}
BufferedImage master = null;
boolean hasBackround = false;
for (int frameIndex = 0;; frameIndex++) {
BufferedImage image;
try{
image = reader.read(frameIndex);
}catch (IndexOutOfBoundsException io){
break;
}
if (width == -1 || height == -1){
width = image.getWidth();
height = image.getHeight();
}
IIOMetadataNode root = (IIOMetadataNode) reader.getImageMetadata(frameIndex).getAsTree("javax_imageio_gif_image_1.0");
IIOMetadataNode gce = (IIOMetadataNode) root.getElementsByTagName("GraphicControlExtension").item(0);
NodeList children = root.getChildNodes();
int delay = Integer.valueOf(gce.getAttribute("delayTime"));
String disposal = gce.getAttribute("disposalMethod");
if (master == null){
master = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
master.createGraphics().setColor(backgroundColor);
master.createGraphics().fillRect(0, 0, master.getWidth(), master.getHeight());
hasBackround = image.getWidth() == width && image.getHeight() == height;
master.createGraphics().drawImage(image, 0, 0, null);
}else{
int x = 0;
int y = 0;
for (int nodeIndex = 0; nodeIndex < children.getLength(); nodeIndex++){
Node nodeItem = children.item(nodeIndex);
if (nodeItem.getNodeName().equals("ImageDescriptor")){
NamedNodeMap map = nodeItem.getAttributes();
x = Integer.valueOf(map.getNamedItem("imageLeftPosition").getNodeValue());
y = Integer.valueOf(map.getNamedItem("imageTopPosition").getNodeValue());
}
}
if (disposal.equals("restoreToPrevious")){
BufferedImage from = null;
for (int i = frameIndex - 1; i >= 0; i--){
if (!frames.get(i).getDisposal().equals("restoreToPrevious") || frameIndex == 0){
from = frames.get(i).getImage();
break;
}
}
{
ColorModel model = from.getColorModel();
boolean alpha = from.isAlphaPremultiplied();
WritableRaster raster = from.copyData(null);
master = new BufferedImage(model, raster, alpha, null);
}
}else if (disposal.equals("restoreToBackgroundColor") && backgroundColor != null){
if (!hasBackround || frameIndex > 1){
master.createGraphics().fillRect(lastx, lasty, frames.get(frameIndex - 1).getWidth(), frames.get(frameIndex - 1).getHeight());
}
}
master.createGraphics().drawImage(image, x, y, null);
lastx = x;
lasty = y;
}
{
BufferedImage copy;
{
ColorModel model = master.getColorModel();
boolean alpha = master.isAlphaPremultiplied();
WritableRaster raster = master.copyData(null);
copy = new BufferedImage(model, raster, alpha, null);
}
frames.add(new ImageFrame(copy, delay, disposal, image.getWidth(), image.getHeight()));
}
master.flush();
}
reader.dispose();
return frames.toArray(new ImageFrame[frames.size()]);
}
And the ImageFrame class:
import java.awt.image.BufferedImage;
public class ImageFrame {
private final int delay;
private final BufferedImage image;
private final String disposal;
private final int width, height;
public ImageFrame (BufferedImage image, int delay, String disposal, int width, int height){
this.image = image;
this.delay = delay;
this.disposal = disposal;
this.width = width;
this.height = height;
}
public ImageFrame (BufferedImage image){
this.image = image;
this.delay = -1;
this.disposal = null;
this.width = -1;
this.height = -1;
}
public BufferedImage getImage() {
return image;
}
public int getDelay() {
return delay;
}
public String getDisposal() {
return disposal;
}
public int getWidth() {
return width;
}
public int getHeight() {
return height;
}
}

Right, I have never done anything even slightly like this before, but a bit of Googling and fiddling in Java got me this:
public ArrayList<BufferedImage> getFrames(File gif) throws IOException{
ArrayList<BufferedImage> frames = new ArrayList<BufferedImage>();
ImageReader ir = new GIFImageReader(new GIFImageReaderSpi());
ir.setInput(ImageIO.createImageInputStream(gif));
for(int i = 0; i < ir.getNumImages(true); i++)
frames.add(ir.getRawImageType(i).createBufferedImage(ir.getWidth(i), ir.getHeight(i)));
return frames;
}
Edit: see Ansel Zandegran's modification to my answer.

To split an animated GIF into separate BufferedImage frames:
try {
ImageReader reader = ImageIO.getImageReadersByFormatName("gif").next();
File input = new File("input.gif");
ImageInputStream stream = ImageIO.createImageInputStream(input);
reader.setInput(stream);
int count = reader.getNumImages(true);
for (int index = 0; index < count; index++) {
BufferedImage frame = reader.read(index);
// Here you go
}
} catch (IOException ex) {
// An I/O problem has occurred
}

Alex's answer covers most cases, but it does have a couple of problems. It doesn't handle transparency correctly (at least according to common convention) and it is applying the current frame's disposal method to the previous frame which is incorrect. Here's a version that does handle those cases correctly:
private ImageFrame[] readGIF(ImageReader reader) throws IOException {
ArrayList<ImageFrame> frames = new ArrayList<ImageFrame>(2);
int width = -1;
int height = -1;
IIOMetadata metadata = reader.getStreamMetadata();
if (metadata != null) {
IIOMetadataNode globalRoot = (IIOMetadataNode) metadata.getAsTree(metadata.getNativeMetadataFormatName());
NodeList globalScreenDescriptor = globalRoot.getElementsByTagName("LogicalScreenDescriptor");
if (globalScreenDescriptor != null && globalScreenDescriptor.getLength() > 0) {
IIOMetadataNode screenDescriptor = (IIOMetadataNode) globalScreenDescriptor.item(0);
if (screenDescriptor != null) {
width = Integer.parseInt(screenDescriptor.getAttribute("logicalScreenWidth"));
height = Integer.parseInt(screenDescriptor.getAttribute("logicalScreenHeight"));
}
}
}
BufferedImage master = null;
Graphics2D masterGraphics = null;
for (int frameIndex = 0;; frameIndex++) {
BufferedImage image;
try {
image = reader.read(frameIndex);
} catch (IndexOutOfBoundsException io) {
break;
}
if (width == -1 || height == -1) {
width = image.getWidth();
height = image.getHeight();
}
IIOMetadataNode root = (IIOMetadataNode) reader.getImageMetadata(frameIndex).getAsTree("javax_imageio_gif_image_1.0");
IIOMetadataNode gce = (IIOMetadataNode) root.getElementsByTagName("GraphicControlExtension").item(0);
int delay = Integer.valueOf(gce.getAttribute("delayTime"));
String disposal = gce.getAttribute("disposalMethod");
int x = 0;
int y = 0;
if (master == null) {
master = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
masterGraphics = master.createGraphics();
masterGraphics.setBackground(new Color(0, 0, 0, 0));
} else {
NodeList children = root.getChildNodes();
for (int nodeIndex = 0; nodeIndex < children.getLength(); nodeIndex++) {
Node nodeItem = children.item(nodeIndex);
if (nodeItem.getNodeName().equals("ImageDescriptor")) {
NamedNodeMap map = nodeItem.getAttributes();
x = Integer.valueOf(map.getNamedItem("imageLeftPosition").getNodeValue());
y = Integer.valueOf(map.getNamedItem("imageTopPosition").getNodeValue());
}
}
}
masterGraphics.drawImage(image, x, y, null);
BufferedImage copy = new BufferedImage(master.getColorModel(), master.copyData(null), master.isAlphaPremultiplied(), null);
frames.add(new ImageFrame(copy, delay, disposal));
if (disposal.equals("restoreToPrevious")) {
BufferedImage from = null;
for (int i = frameIndex - 1; i >= 0; i--) {
if (!frames.get(i).getDisposal().equals("restoreToPrevious") || frameIndex == 0) {
from = frames.get(i).getImage();
break;
}
}
master = new BufferedImage(from.getColorModel(), from.copyData(null), from.isAlphaPremultiplied(), null);
masterGraphics = master.createGraphics();
masterGraphics.setBackground(new Color(0, 0, 0, 0));
} else if (disposal.equals("restoreToBackgroundColor")) {
masterGraphics.clearRect(x, y, image.getWidth(), image.getHeight());
}
}
reader.dispose();
return frames.toArray(new ImageFrame[frames.size()]);
}
private class ImageFrame {
private final int delay;
private final BufferedImage image;
private final String disposal;
public ImageFrame(BufferedImage image, int delay, String disposal) {
this.image = image;
this.delay = delay;
this.disposal = disposal;
}
public BufferedImage getImage() {
return image;
}
public int getDelay() {
return delay;
}
public String getDisposal() {
return disposal;
}
}
There is a good description of how GIF animations work in this ImageMagick tutorial.

I wrote a GIF image decoder on my own and released it under the Apache License 2.0 on GitHub. You can download it here: https://github.com/DhyanB/Open-Imaging. Example usage:
void example(final byte[] data) throws Exception {
final GifImage gif = GifDecoder .read(data);
final int width = gif.getWidth();
final int height = gif.getHeight();
final int background = gif.getBackgroundColor();
final int frameCount = gif.getFrameCount();
for (int i = 0; i < frameCount; i++) {
final BufferedImage img = gif.getFrame(i);
final int delay = gif.getDelay(i);
ImageIO.write(img, "png", new File(OUTPATH + "frame_" + i + ".png"));
}
}
The decoder supports GIF87a, GIF89a, animation, transparency and interlacing. Frames will have the width and height of the image itself and be placed on the correct position on the canvas. It respects frame transparency and disposal methods. Checkout the project description for more details such as the handling of background colors.
Additionally, the decoder doesn't suffer from this ImageIO bug: ArrayIndexOutOfBoundsException: 4096 while reading gif file.
I'd be happy to get some feedback. I've been testing with a representive set of images, however, some real field testing would be good.

Using c24w's solution, replace:
frames.add(ir.getRawImageType(i).createBufferedImage(ir.getWidth(i), ir.getHeight(i)));
With:
frames.add(ir.read(i));

Tensorflow in Android: java.nio.BufferOverFlowException

Good morning. I'm a developer trying to put a tensorflow model into Android.
I've encountered an error that I've never seen before while trying to fix it with multiple errors.
The java.nio.BufferOverFlowException error i'm facing now is that it didn't happen before, but it happened suddenly.
My code uses a byte array, but i cannot specify which part is the problem.
This source that takes a float array as input and returns an array with 10 classes after passing through the model.
The returned values have softmax value.
public float[] hypothesis(float[] inputFloats, int nFeatures, int nClasses, Context context)
{
try {
int nInstance = inputFloats.length / nFeatures;
// FloatBuffer.wrap(inputFloats);
Toast.makeText(context, "", Toast.LENGTH_LONG).show();
inferenceInterface.feed(INPUT_NODE, FloatBuffer.wrap(inputFloats), INPUT_SIZE);
inferenceInterface.run(OUTPUT_NODES_HYPO);
float[] result = new float[nInstance * nClasses];
inferenceInterface.fetch(OUTPUT_NODE_HYPO, result);
return result;
}
catch(Exception e){
Toast.makeText(context, e+" ...", Toast.LENGTH_LONG).show();
return null;
}
}
The length of the inputfloats is 720 and the nFeatures is 720. nClasses is 10.
Although the value is not correct, it worked before.
e in the catch statement prints java.nio.BufferOverFlowException.
Could there be a problem in the middle of converting a byte array to a float array?
Related source.
public float[] bytetofloat(byte[] array){
int[] returnArr = new int[array.length/4];
float[] returnArr1 = new float[array.length/4];
for(int i = 0 ; i < returnArr.length; i++){
//array[i] = 0;
returnArr[i] = array[i*4] & 0xFF;
if(returnArr[i] < 0 || returnArr[i]>255)
Log.d("ARRAY", returnArr[i]+" ");
returnArr1[i] = (float)returnArr[i];
}
return returnArr1;
}
public Bitmap RGB2GRAY(Bitmap image){
int width = image.getWidth();
int height = image.getHeight();
Bitmap bmOut;
bmOut = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_4444);
for(int x = 0; x < width; x++){
for(int y = 0 ; y < height; y++){
int pixel = image.getPixel(x, y);
int A = Color.alpha(pixel);
int R = Color.red(pixel);
int G = Color.green(pixel);
int B = Color.blue(pixel);
R = G = B = (int)(0.2126 * R + 0.7152 * G + 0.0722 * B);
bmOut.setPixel(x, y, Color.argb(A, R, G, B));
}
}
return bmOut;
}
private void activityPrediction(float[] inputArray){
try {
float[] result = activityInference.hypothesis(inputArray, 20*36, 10, getApplicationContext());
predictionView.setText(Arrays.toString(result));
}
catch (Exception e){
Toast.makeText(getApplicationContext(), e.getMessage(), Toast.LENGTH_LONG).show();
}
}
private byte[] bitmapToByteArray(Bitmap bitmap)
{
int chunkNumbers = 10;
int bitmapSize = bitmap.getRowBytes() * bitmap.getHeight();
byte[] imageBytes = new byte[bitmapSize];
int rows, cols;
int chunkHeight, chunkWidth;
rows = cols = (int) Math.sqrt(chunkNumbers);
chunkHeight = bitmap.getHeight() / rows;
chunkWidth = bitmap.getWidth() / cols;
int yCoord = 0;
int bitmapsSizes = 0;
for (int x = 0; x < rows; x++)
{
int xCoord = 0;
for (int y = 0; y < cols; y++)
{
Bitmap bitmapChunk = Bitmap.createBitmap(bitmap, xCoord, yCoord, chunkWidth, chunkHeight);
byte[] bitmapArray = getBytesFromBitmapChunk(bitmapChunk);
System.arraycopy(bitmapArray, 0, imageBytes, bitmapsSizes, bitmapArray.length);
bitmapsSizes = bitmapsSizes + bitmapArray.length;
xCoord += chunkWidth;
bitmapChunk.recycle();
bitmapChunk = null;
}
yCoord += chunkHeight;
}
return imageBytes;
}
private byte[] getBytesFromBitmapChunk(Bitmap bitmap)
{
int bitmapSize = bitmap.getRowBytes() * bitmap.getHeight();
ByteBuffer byteBuffer = ByteBuffer.allocate(bitmapSize);
bitmap.copyPixelsToBuffer(byteBuffer);
byteBuffer.rewind();
return byteBuffer.array();
}
'e.printStackTrace()' result
at com.example.leehanbeen.platerecognize.ActivityInference.hypothesis(ActivityInference.java:58)
at com.example.leehanbeen.platerecognize.MainActivity.activityPrediction(MainActivity.java:148)
at com.example.leehanbeen.platerecognize.MainActivity.access$100(MainActivity.java:28)
at com.example.leehanbeen.platerecognize.MainActivity$2.onClick(MainActivity.java:69)
around MainActivity.java:69
byte[] byteArrayRes = bitmapToByteArray(image_bitmap);
float[] inputArray = bytetofloat(byteArrayRes);
activityPrediction(inputArray);
MainActivity.java:28
public class MainActivity extends AppCompatActivity {
MainActivity.java:148
float[] result = activityInference.hypothesis(inputArray, 20*36, 10, getApplicationContext());
around ActivityInference.java:58
float[] result = new float[nInstance * nClasses];
inferenceInterface.fetch(OUTPUT_NODE_HYPO, result);

org.eclipse.swt.SWTException: Unsupported color depth

I have created a sample SWT application. I am uploading few images into the application. I have to resize all the images which are above 16x16 (Width*Height) resolution and save those in separate location.
For this reason I am scaling the image and saving the scaled image to my destination location. Below is the piece of code which I am using to do that.
Using getImageData() to get the image data and to save I am using ImageLoader save() method.
final Image mySampleImage = ImageResizer.scaleImage(img, 16, 16);
final ImageLoader imageLoader = new ImageLoader();
imageLoader.data = new ImageData[] { mySampleImage.getImageData() };
final String fileExtension = inputImagePath.substring(inputImagePath.lastIndexOf(".") + 1);
if ("GIF".equalsIgnoreCase(fileExtension)) {
imageLoader.save(outputImagePath, SWT.IMAGE_GIF);
} else if ("PNG".equalsIgnoreCase(fileExtension)) {
imageLoader.save(outputImagePath, SWT.IMAGE_PNG);
}
ImageLoader imageLoader.save(outputImagePath, SWT.IMAGE_GIF); is throwing the below exeception when I am trying to save few specific images (GIF or PNG format).
org.eclipse.swt.SWTException: Unsupported color depth
at org.eclipse.swt.SWT.error(SWT.java:4533)
at org.eclipse.swt.SWT.error(SWT.java:4448)
at org.eclipse.swt.SWT.error(SWT.java:4419)
at org.eclipse.swt.internal.image.GIFFileFormat.unloadIntoByteStream(GIFFileFormat.java:427)
at org.eclipse.swt.internal.image.FileFormat.unloadIntoStream(FileFormat.java:124)
at org.eclipse.swt.internal.image.FileFormat.save(FileFormat.java:112)
at org.eclipse.swt.graphics.ImageLoader.save(ImageLoader.java:218)
at org.eclipse.swt.graphics.ImageLoader.save(ImageLoader.java:259)
at mainpackage.ImageResizer.resize(ImageResizer.java:55)
at mainpackage.ImageResizer.main(ImageResizer.java:110)
Let me know If there is any other way to do the same (or) there is any way to resolve this issue.

Finally I got a solution by referring to this existing eclipse bug Unsupported color depth eclipse bug.
In the below code i have created a PaletteData with RGB values and updated my Image Data.
My updateImagedata() method will take the scaled image and will return the proper updated imageData if the image depth is 32 or more.
private static ImageData updateImagedata(Image image) {
ImageData data = image.getImageData();
if (!data.palette.isDirect && data.depth <= 8)
return data;
// compute a histogram of color frequencies
HashMap<RGB, ColorCounter> freq = new HashMap<>();
int width = data.width;
int[] pixels = new int[width];
int[] maskPixels = new int[width];
for (int y = 0, height = data.height; y < height; ++y) {
data.getPixels(0, y, width, pixels, 0);
for (int x = 0; x < width; ++x) {
RGB rgb = data.palette.getRGB(pixels[x]);
ColorCounter counter = (ColorCounter) freq.get(rgb);
if (counter == null) {
counter = new ColorCounter();
counter.rgb = rgb;
freq.put(rgb, counter);
}
counter.count++;
}
}
// sort colors by most frequently used
ColorCounter[] counters = new ColorCounter[freq.size()];
freq.values().toArray(counters);
Arrays.sort(counters);
// pick the most frequently used 256 (or fewer), and make a palette
ImageData mask = null;
if (data.transparentPixel != -1 || data.maskData != null) {
mask = data.getTransparencyMask();
}
int n = Math.min(256, freq.size());
RGB[] rgbs = new RGB[n + (mask != null ? 1 : 0)];
for (int i = 0; i < n; ++i)
rgbs[i] = counters[i].rgb;
if (mask != null) {
rgbs[rgbs.length - 1] = data.transparentPixel != -1 ? data.palette.getRGB(data.transparentPixel)
: new RGB(255, 255, 255);
}
PaletteData palette = new PaletteData(rgbs);
ImageData newData = new ImageData(width, data.height, 8, palette);
if (mask != null)
newData.transparentPixel = rgbs.length - 1;
for (int y = 0, height = data.height; y < height; ++y) {
data.getPixels(0, y, width, pixels, 0);
if (mask != null)
mask.getPixels(0, y, width, maskPixels, 0);
for (int x = 0; x < width; ++x) {
if (mask != null && maskPixels[x] == 0) {
pixels[x] = rgbs.length - 1;
} else {
RGB rgb = data.palette.getRGB(pixels[x]);
pixels[x] = closest(rgbs, n, rgb);
}
}
newData.setPixels(0, y, width, pixels, 0);
}
return newData;
}
To find minimum index:
static int closest(RGB[] rgbs, int n, RGB rgb) {
int minDist = 256*256*3;
int minIndex = 0;
for (int i = 0; i < n; ++i) {
RGB rgb2 = rgbs[i];
int da = rgb2.red - rgb.red;
int dg = rgb2.green - rgb.green;
int db = rgb2.blue - rgb.blue;
int dist = da*da + dg*dg + db*db;
if (dist < minDist) {
minDist = dist;
minIndex = i;
}
}
return minIndex;
}
ColourCounter Class:
class ColorCounter implements Comparable<ColorCounter> {
RGB rgb;
int count;
public int compareTo(ColorCounter o) {
return o.count - count;
}
}

Converting monochrome image to minimum number of 2d shapes

Basically, what I need to do is take a 2d array of bitflags and produce a list of 2d rectangles to fill the entire area with the minimum number of total shapes required to perfectly fill the space. I am doing this to convert a 2d top-down monochrome of a map into 2d rectangle shapes which perfectly represent the passed in image which will be used to generate a platform in a 3d world. I need to minimize the total number of shapes used, because each shape will represent a separate object, and flooding it with 1 unit sized squares for each pixel would be highly inefficient for that engine.
So far I have read in the image, processed it, and filled a two dimensional array of booleans which tells me if the pixel should be filled or unfilled, but I am unsure of the most efficient approach of continuing.
Here is what I have so far, as reference, if you aren't following:
public static void main(String[] args) {
File file = new File(args[0]);
BufferedImage bi = null;
try {
bi = ImageIO.read(file);
} catch (IOException ex) {
Logger.global.log(Level.SEVERE, null, ex);
}
if (bi != null) {
int[] rgb = bi.getRGB(0, 0, bi.getWidth(), bi.getHeight(), new int[bi.getWidth() * bi.getHeight()], 0, bi.getWidth());
Origin origin = new Origin(bi.getWidth() / 2, bi.getHeight() / 2);
boolean[][] flags = new boolean[bi.getWidth()][bi.getHeight()];
for (int y = 0; y < bi.getHeight(); y++) {
for (int x = 0; x < bi.getWidth(); x++) {
int index = y * bi.getWidth() + x;
int color = rgb[index];
int type = color == Color.WHITE.getRGB() ? 1 : (color == Color.RED.getRGB() ? 2 : 0);
if (type == 2) {
origin = new Origin(x, y);
}
flags[x][y] = type != 1;
}
}
List<Rectangle> list = new ArrayList();
//Fill list with rectangles
}
}
White represents no land. Black or Red represents land. The check for the red pixel marks the origin position of map, which was just for convenience and the rectangles will be offset by the origin position if it is found.
Edit: The processing script does not need to be fast, the produced list of rectangles will be dumped and that will be what will be imported and used later, so the processing of the image does not need to be particularly optimized, it doesn't make a difference.
I also just realized that expecting a 'perfect' solution is expecting too much, since this would qualify as a 'knapsack problem' of the multidimensionally constrained variety, if I am expecting exactly the fewest number of rectangles, so simply an algorithm that produces a minimal number of rectangles will suffice.
Here is a reference image for completion:
Edit 2: It doesn't look like this is such an easy thing to answer given no feedback yet, but I have started making progress, but I am sure I am missing something that would vastly reduce the number of rectangles. Here is the updated progress:
static int mapWidth;
static int mapHeight;
public static void main(String[] args) {
File file = new File(args[0]);
BufferedImage bi = null;
System.out.println("Reading image...");
try {
bi = ImageIO.read(file);
} catch (IOException ex) {
Logger.global.log(Level.SEVERE, null, ex);
}
if (bi != null) {
System.out.println("Complete!");
System.out.println("Interpreting image...");
mapWidth = bi.getWidth();
mapHeight = bi.getHeight();;
int[] rgb = bi.getRGB(0, 0, mapWidth, mapHeight, new int[mapWidth * mapHeight], 0, mapWidth);
Origin origin = new Origin(mapWidth / 2, mapHeight / 2);
boolean[][] flags = new boolean[mapWidth][mapHeight];
for (int y = 0; y < mapHeight; y++) {
for (int x = 0; x < mapWidth; x++) {
int index = y * mapWidth + x;
int color = rgb[index];
int type = color == Color.WHITE.getRGB() ? 1 : (color == Color.RED.getRGB() ? 2 : 0);
if (type == 2) {
origin = new Origin(x, y);
}
flags[x][y] = type != 1;
}
}
System.out.println("Complete!");
System.out.println("Processing...");
//Get Rectangles to fill space...
List<Rectangle> rectangles = getRectangles(flags, origin);
System.out.println("Complete!");
float rectangleCount = rectangles.size();
float totalCount = mapHeight * mapWidth;
System.out.println("Total units: " + (int)totalCount);
System.out.println("Total rectangles: " + (int)rectangleCount);
System.out.println("Rectangle reduction factor: " + ((1 - rectangleCount / totalCount) * 100.0) + "%");
System.out.println("Dumping data...");
try {
file = new File(file.getParentFile(), file.getName() + "_Rectangle_Data.txt");
if(file.exists()){
file.delete();
}
file.createNewFile();
BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file)));
for(Rectangle rect: rectangles){
bw.write(rect.x + "," + rect.y + "," + rect.width + ","+ rect.height + "\n");
}
bw.flush();
bw.close();
} catch (Exception ex) {
Logger.global.log(Level.SEVERE, null, ex);
}
System.out.println("Complete!");
}else{
System.out.println("Error!");
}
}
public static void clearRange(boolean[][] flags, int xOff, int yOff, int width, int height) {
for (int y = yOff; y < yOff + height; y++) {
for (int x = xOff; x < xOff + width; x++) {
flags[x][y] = false;
}
}
}
public static boolean checkIfFilled(boolean[][] flags, int xOff, int yOff, int width, int height) {
for (int y = yOff; y < yOff + height; y++) {
for (int x = xOff; x < xOff + width; x++) {
if (!flags[x][y]) {
return false;
}
}
}
return true;
}
public static List<Rectangle> getRectangles(boolean[][] flags, Origin origin) {
List<Rectangle> rectangles = new ArrayList();
for (int y = 0; y < mapHeight; y++) {
for (int x = 0; x < mapWidth; x++) {
if (flags[x][y]) {
int maxWidth = 1;
int maxHeight = 1;
Loop:
//The search size limited to 400x400 so it will complete some time this century.
for (int w = Math.min(400, mapWidth - x); w > 1; w--) {
for (int h = Math.min(400, mapHeight - y); h > 1; h--) {
if (w * h > maxWidth * maxHeight) {
if (checkIfFilled(flags, x, y, w, h)) {
maxWidth = w;
maxHeight = h;
break Loop;
}
}
}
}
//Search also in the opposite direction
Loop:
for (int h = Math.min(400, mapHeight - y); h > 1; h--) {
for (int w = Math.min(400, mapWidth - x); w > 1; w--) {
if (w * h > maxWidth * maxHeight) {
if (checkIfFilled(flags, x, y, w, h)) {
maxWidth = w;
maxHeight = h;
break Loop;
}
}
}
}
rectangles.add(new Rectangle(x - origin.x, y - origin.y, maxWidth, maxHeight));
clearRange(flags, x, y, maxWidth, maxHeight);
}
}
}
return rectangles;
}
My current code's search for larger rectangles is limited to 400x400 to speed up testing, and outputs 17,979 rectangles, which is a 99.9058% total reduction of rectangles if I treated each pixel as a 1x1 square(19,095,720 pixels). So far so good.

Java mirror image diagonal method not working

I'm having trouble getting my method to work. The method should mirror any image I choose on its diagonal to produce a mirror effect, but at the moment it just produces the same image unedited and I don't what I'm doing wrong. Any help would be greatly appreciated. Thank you.
public Picture mirrorImageDiagonal() {
int size = this.getWidth();
Pixel rightPixel = null;
Pixel leftTargetPixel = null;
Pixel rightTargetPixel = null;
Picture target = new Picture(size, size);
for (double x = 0; x < size; x ++) {
for (double y = 0; y <= x; y ++) {
int yIndex = Math.min((int) y, this.getHeight() - 1);
int xIndex = Math.min((int) x, this.getWidth() - 1);
leftTargetPixel = target.getPixel(yIndex, xIndex);
rightTargetPixel = target.getPixel(xIndex, yIndex);
rightPixel = this.getPixel(xIndex, yIndex);
rightTargetPixel.setColor(rightPixel.getColor());
leftTargetPixel.setColor(rightPixel.getColor());
}
}
return target;
}

I am assuming that you are trying to complete the challenge for A6 in the picture lab packet. I just completed this for school, but if you are not, I hope this still helps you.
public void mirrorDiagonal()
{
Pixel[][] pixels = this.getPixels2D();
Pixel pixel1 = null;
Pixel pixel2 = null;
int width = pixels[0].length;
for (int row = 0; row < pixels.length; row++)
{
for (int col = 0; col < width; col++)
{
if (col < pixels.length)
{
pixel1 = pixels[row][col];
pixel2 = pixels[col][row];
pixel1.setColor(pixel2.getColor());
}
}
}
}