我想从 Android 中的图像生成直方图。我确实在java中找到了几个例子，但我没有成功移植它。
以下是我使用的代码 - 目前我正在NoClassDefFoundException上课javax.imageio.ImageIo。
public static byte[] histogramEqualization(String path) {
int red;
int green;
int blue;
int alpha;
int newPixel = 0;
original = null;
try {
original = ImageIO.read(new URL(path));
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
// Get the Lookup table for histogram equalization
ArrayList<int[]> histLUT = histogramEqualizationLUT(original);
BufferedImage histogramEQ = new BufferedImage(original.getWidth(), original.getHeight(), original.getType());
for(int i=0; i<original.getWidth(); i++) {
for(int j=0; j<original.getHeight(); j++) {
// Get pixels by R, G, B
alpha = new Color(original.getRGB (i, j)).getAlpha();
red = new Color(original.getRGB (i, j)).getRed();
green = new Color(original.getRGB (i, j)).getGreen();
blue = new Color(original.getRGB (i, j)).getBlue();
// Set new pixel values using the histogram lookup table
red = histLUT.get(0)[red];
green = histLUT.get(1)[green];
blue = histLUT.get(2)[blue];
// Return back to original format
newPixel = colorToRGB(alpha, red, green, blue);
// Write pixels into image
histogramEQ.setRGB(i, j, newPixel);
}
}
//create a ByteArrayOutputStream
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] imageInByte = null;
//write our image to it
try {
ImageIO.write( histogramEQ, "png", baos );
//flush the stream
baos.flush();
//get the image in byte form
imageInByte = baos.toByteArray();
//close the stream
baos.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// return histogramEQ;
return imageInByte;
}
// Get the histogram equalization lookup table for separate R, G, B channels
public static ArrayList<int[]> histogramEqualizationLUT(BufferedImage input) {
// Get an image histogram - calculated values by R, G, B channels
ArrayList<int[]> imageHist = imageHistogram(input);
// Create the lookup table
ArrayList<int[]> imageLUT = new ArrayList<int[]>();
// Fill the lookup table
int[] rhistogram = new int[256];
int[] ghistogram = new int[256];
int[] bhistogram = new int[256];
for(int i=0; i<rhistogram.length; i++) rhistogram[i] = 0;
for(int i=0; i<ghistogram.length; i++) ghistogram[i] = 0;
for(int i=0; i<bhistogram.length; i++) bhistogram[i] = 0;
long sumr = 0;
long sumg = 0;
long sumb = 0;
// Calculate the scale factor
float scale_factor = (float) (255.0 / (input.getWidth() * input.getHeight()));
for(int i=0; i<rhistogram.length; i++) {
sumr += imageHist.get(0)[i];
int valr = (int) (sumr * scale_factor);
if(valr > 255) {
rhistogram[i] = 255;
}
else rhistogram[i] = valr;
sumg += imageHist.get(1)[i];
int valg = (int) (sumg * scale_factor);
if(valg > 255) {
ghistogram[i] = 255;
}
else ghistogram[i] = valg;
sumb += imageHist.get(2)[i];
int valb = (int) (sumb * scale_factor);
if(valb > 255) {
bhistogram[i] = 255;
}
else bhistogram[i] = valb;
}
imageLUT.add(rhistogram);
imageLUT.add(ghistogram);
imageLUT.add(bhistogram);
return imageLUT;
}
private static int colorToRGB(int alpha, int red, int green, int blue) {
int newPixel = 0;
newPixel += alpha; newPixel = newPixel << 8;
newPixel += red; newPixel = newPixel << 8;
newPixel += green; newPixel = newPixel << 8;
newPixel += blue;
return newPixel;
}
public static ArrayList<int[]> imageHistogram(BufferedImage input) {
int[] rhistogram = new int[256];
int[] ghistogram = new int[256];
int[] bhistogram = new int[256];
for(int i=0; i<rhistogram.length; i++) rhistogram[i] = 0;
for(int i=0; i<ghistogram.length; i++) ghistogram[i] = 0;
for(int i=0; i<bhistogram.length; i++) bhistogram[i] = 0;
for(int i=0; i<input.getWidth(); i++) {
for(int j=0; j<input.getHeight(); j++) {
int red = new Color(input.getRGB (i, j)).getRed();
int green = new Color(input.getRGB (i, j)).getGreen();
int blue = new Color(input.getRGB (i, j)).getBlue();
// Increase the values of colors
rhistogram[red]++; ghistogram[green]++; bhistogram[blue]++;
}
}
ArrayList<int[]> hist = new ArrayList<int[]>();
hist.add(rhistogram);
hist.add(ghistogram);
hist.add(bhistogram);
return hist;
}
这是我得到的错误。
01-25 18:05:37.548: E/AndroidRuntime(3514): FATAL EXCEPTION: main
01-25 18:05:37.548: E/AndroidRuntime(3514): java.lang.NoClassDefFoundError: javax.imageio.ImageIO
01-25 18:05:37.548: E/AndroidRuntime(3514): at com.example.histogramsample.MainActivity.histogramEqualization(MainActivity.java:57)
01-25 18:05:37.548: E/AndroidRuntime(3514): at com.example.histogramsample.MainActivity.onCreate(MainActivity.java:33)
01-25 18:05:37.548: E/AndroidRuntime(3514): at android.app.Activity.performCreate(Activity.java:4465)
01-25 18:05:37.548: E/AndroidRuntime(3514): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1053)
01-25 18:05:37.548: E/AndroidRuntime(3514): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1934)
01-25 18:05:37.548: E/AndroidRuntime(3514): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1995)
01-25 18:05:37.548: E/AndroidRuntime(3514): at android.app.ActivityThread.access$600(ActivityThread.java:128)
01-25 18:05:37.548: E/AndroidRuntime(3514): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1161)
01-25 18:05:37.548: E/AndroidRuntime(3514): at android.os.Handler.dispatchMessage(Handler.java:99)
01-25 18:05:37.548: E/AndroidRuntime(3514): at android.os.Looper.loop(Looper.java:137)
01-25 18:05:37.548: E/AndroidRuntime(3514): at android.app.ActivityThread.main(ActivityThread.java:4514)
01-25 18:05:37.548: E/AndroidRuntime(3514): at java.lang.reflect.Method.invokeNative(Native Method)
01-25 18:05:37.548: E/AndroidRuntime(3514): at java.lang.reflect.Method.invoke(Method.java:511)
01-25 18:05:37.548: E/AndroidRuntime(3514): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:790)
01-25 18:05:37.548: E/AndroidRuntime(3514): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:557)
01-25 18:05:37.548: E/AndroidRuntime(3514): at dalvik.system.NativeStart.main(Native Method)