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Search for color in BufferedImage Java

I currently have a script that can create a bufferedimage of the screen, and then list the value for a specific pixel. However, I'm trying to search the entire bufferedimage for a specific color. Is there a way to do this?
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
public class Main {
public static void main(String args[]) throws IOException, AWTException {
BufferedImage image = new Robot().createScreenCapture(new Rectangle(Toolkit.getDefaultToolkit().getScreenSize()));
int x = 10;
int y = 10;
int clr = image.getRGB(x, y);
int red = (clr & 0x00ff0000) >> 16;
int green = (clr & 0x0000ff00) >> 8;
int blue = clr & 0x000000ff;
System.out.println("Red = " + red);
System.out.println("Green = " + green);
System.out.println("Blue = " + blue);
}
}

You could use nested for loops for every (x, y) coordinate of the image (with x between 0 and image.getWidth(), and y between 0 and image.getHeight()) and compare if the color at the given position is equal to the color you are looking for.

How do I make the for loops for this code? (I need to check a region of an image for a certain color.)

According to Get color of each pixel of an image using BufferedImages, the following code needs for loops for its intended purpose to work.
public class GetPixelColor
{
public static void main(String args[]) throws IOException{
File file= new File("your_file.jpg");
BufferedImage image = ImageIO.read(file);
// Getting pixel color by position x and y
int clr= image.getRGB(x,y);
int red = (clr & 0x00ff0000) >> 16;
int green = (clr & 0x0000ff00) >> 8;
int blue = clr & 0x000000ff;
System.out.println("Red Color value = "+ red);
System.out.println("Green Color value = "+ green);
System.out.println("Blue Color value = "+ blue);
}
}
How do I define the region of the image I would like to check for its color with for loops?

the region you want to read it's color is a rectangle between two points p1(x1,y1), p2(x2,y2)
and you scan that rectangle by two nested for loops like this
for(int x=x1; x<=x2; x++)
for(int y=y1; y<=y2; y++){
// Getting pixel color by position x and y
int clr= image.getRGB(x,y);
int red = (clr & 0x00ff0000) >> 16;
int green = (clr & 0x0000ff00) >> 8;
int blue = clr & 0x000000ff;
System.out.println("Red Color value = "+ red);
System.out.println("Green Color value = "+ green);
System.out.println("Blue Color value = "+ blue);
}

You can simply use two nested for loops to loop through the image, something like this:
public static void printPixelColors(BufferedImage img) {
int imageWidth = img.getWidth();
int imageHeight = img.getHeight();
for (int y = 0; y < imageHeight; y++) {
for (int x = 0; x < imageWidth; x++) {
// Getting pixel color by position x and y
int clr = img.getRGB(x, y);
int red = (clr & 0x00ff0000) >> 16;
int green = (clr & 0x0000ff00) >> 8;
int blue = clr & 0x000000ff;
System.out.println("Red Color value = " + red);
System.out.println("Green Color value = " + green);
System.out.println("Blue Color value = " + blue);
}
}
}

Converting certain pixels' RGB color to another color

Programming Language: Java
I am trying to convert certain pixels of this image to a different color to reveal a "Secret Message."
Most of the pixels are:
Red = 0, Green = 64, Blue = 0
The pixels that I want changed to R = 255, G = 255, B = 255 are:
Red = 5, Green = 64, Blue = 5
import java.io.File;
import java.io.IOException;
import java.awt.image.BufferedImage;
import javax.imageio.ImageIO;
import java.awt.Color;
public class ASSN2p2
{
private static int makeRGBColor(int red, int green, int blue)
{
int rgb = 0;
rgb = red*65536 + green*256 + blue;
return rgb;
}
private static int getRed(int pixel)
{
return (pixel >> 16) & 0xFF;
}
private static int getGreen(int pixel)
{
return (pixel >> 8) & 0xFF;
}
private static int getBlue(int pixel)
{
return (pixel) & 0xFF;
}
public static void main(String args[]) throws IOException
{
// int width = 300;
// int height = 200;
BufferedImage image = null;
File f = null;
try
{
f = new File("D:\\2016-2017\\Fall2016\\201_CSCE_Programming\\Assignment 2\\secretmessage.png");
image = ImageIO.read(f);
image = new BufferedImage(image.getWidth(), image.getHeight(), BufferedImage.TYPE_INT_ARGB);
System.out.println("Reading Complete");
BufferedImage output = new BufferedImage(image.getWidth(), image.getHeight(),BufferedImage.TYPE_INT_ARGB);
//--------------------------------------
//-------------------------------------------
for (int y = 0; y < image.getHeight(); y++)
{
for (int x = 0; x < image.getWidth(); x++)
{
int pixel = image.getRGB(x, y);
int r,g,b;
r = getRed(pixel);
g = getGreen(pixel);
b = getBlue(pixel);
if ((r == 5) && (g == 64) && (b == 5))
{
r = 64;
b = 64;
b = 64;
image.setRGB(x,y,makeRGBColor(r,g,b));
} }
}
}
catch(IOException e)
{
System.out.println("Error: "+e);
}
// printPixelARGB(pixel);
// System.out.println("");
try
{
f = new File("D:\\2016-2017\\Fall2016\\201_CSCE_Programming\\Assignment 2\\output.png");
ImageIO.write(image, "png", f);
System.out.println("Writing Complete");
}
catch(IOException e)
{
System.out.println("Error: "+e);
}
}
}
This produces this:
I am having trouble understanding what has gone wrong!
Any assistance will be appreciated!

I believe that you're missing the alpha component of your new color. Change your code to:
private static int makeRGBColor(int red, int green, int blue) {
int rgb = 0xff000000 | (red << 16) | (green << 8) | blue;
return rgb;
}
to make sure that the alpha is set to full, otherwise your image will look completely transparent.

How to extract Y, Cb and Cr color components?

I need to decompose a given colored picture in three separate pictures, so that each color component (Y, Cb, Cr) is stored in one picture like here.
Maybe has an idea how I could get these three pictures with
separately Y, Cb or Cr color components? With following peace of code I can just read out the file and convert the color model from RGB to YCbCr.
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
public class SpaceConverter {
static int [] colorComponentsYCbCr = new int[3];
static int [] colorComponentsRGB = new int[3];
public static void getRGBComponents (int color)
{
colorComponentsRGB [0] = (color & 0xff);
colorComponentsRGB [1] = (color & 0x00ff) >> 8;
colorComponentsRGB [2] = (color & 0x0000ff) >> 16;
}
public static void convertYCbCr2RGB(int [] componentsYCbCrToConvert)
{
int Y = componentsYCbCrToConvert [0];
int Cb = componentsYCbCrToConvert [1];
int Cr = componentsYCbCrToConvert [2];
colorComponentsRGB = new int [3];
colorComponentsRGB [0] = (int) (Y + 1.402 * (Cr - 128));
colorComponentsRGB [1] = (int) (Y - 0.34414 * (Cb - 128) - 0.71414 * (Cr - 128));
colorComponentsRGB [2] = (int) (Y + 1.772 * (Cb - 128));
}
public static void convertRGB2YCbCr(int [] componentsRGB)
{
int blue = componentsRGB [0];
int green = componentsRGB [1];
int red = componentsRGB [2];
colorComponentsYCbCr [0] = (int) (0.299 * red + 0.587 * green + 0.114 * blue);
colorComponentsYCbCr [1] = (int) (128-0.169 * red-0.331 * green + 0.500 * blue);
colorComponentsYCbCr [2] = (int) (128+0.500 * red - 0.419 * green - 0.081 * blue);
}
public static void getColoredCrPicture(BufferedImage image)
{
File f = null;
// get width and height
int width = image.getWidth();
int height = image.getHeight();
for (int y = 0; y<height; y++)
{
for (int x = 0; x<width; x++)
{
int color = image.getRGB(x, y);
getRGBComponents(color);
convertRGB2YCbCr(colorComponentsRGB);
int Y = colorComponentsYCbCr[0];
int Cb = colorComponentsYCbCr[1];
int Cr = colorComponentsYCbCr[2];
Y = 0;
Cb = 0;
int p = (Y << 24) | (Cb << 16) | (Cr<<8);
image.setRGB(x, y, p);
}
}
try
{
f = new File("/Users/MAC/Documents/workspace/ColorConverter/src/outputX.jpg");
ImageIO.write(image, "jpg", f);
}
catch(IOException e)
{
System.out.println(e);
}
}
public static void getColoredCbPicture(BufferedImage image)
{
File f = null;
// get width and height
int width = image.getWidth();
int height = image.getHeight();
for (int y = 0; y<height; y++)
{
for (int x = 0; x<width; x++)
{
int color = image.getRGB(x, y);
getRGBComponents(color);
convertRGB2YCbCr(colorComponentsRGB);
int Y = colorComponentsYCbCr[0];
int Cb = colorComponentsYCbCr[1];
int Cr = colorComponentsYCbCr[2];
Y = 0;
Cr = 0;
int p = (Y << 24) | (Cb<< 16) | (Cr <<8);
image.setRGB(x, y, p);
}
}
try
{
f = new File("/Users/MAC/Documents/workspace/ColorConverter/src/outputCb.jpg");
ImageIO.write(image, "jpg", f);
System.out.println("WRITE Status: OK");
}
catch(IOException e)
{
System.out.println(e);
}
}
public static BufferedImage loadPicture()
{
File f = null;
BufferedImage img = null;
// read Image
try
{
f = new File("/Users/MAC/Documents/workspace/ColorConverter/src/VILLA.JPG");
img = ImageIO.read(f);
System.out.println("READ Status: OK");
getColoredCbPicture(img);
}
catch(IOException e)
{
System.out.println(e);
}
return img;
}
public static void main(String[] args)
{
BufferedImage image = null;
loadPicture();
getColoredCbPicture(image);
}
}

It sounds like what you are looking to do is take an RGB image, convert it to YCbCr and display each of the three channels in YCbCr as a separate RGB image.
You already have code that converts from RGB to YCbCr . You will also need code that will do the reverse conversion so you can go from YCbCr to RGB.
You will want to use this same logic, but actually create three Y'CrCb images: (Y, 0, 0), (0, Cb, 0) and (0, 0, Cr). Then convert each of these three images to RGB. These three images will be an RGB representation of each of the three YCbCr channels.

Error stated that the program cannot find symbol for hexa2 and hexa4

I'm a beginner to Java programming. I have the algorithm but I'm having trouble to code it. I would like to compare 2 similar images at position 2 and 4 of RGB hexadecimal pixel values to check whether one of the images has different pixel values than the other one.
My Algorithm logic:
if(image1.substring2 == image2.substring2) && (image1.substring4 == image2.substring4), pixels are the same.
if(image1.substring2 != image2.substring2) || (image1.substring4 != image2.substring4), pixels are not the same.
if(image1.substring2 != image2.substring2) && (image1.substring4 != image2.substring4), pixels are not the same.
I have the remaining codes here. I tried to separate all the process so it is easy for me to troubleshoot later.
//MAIN
public class getPixelRGB1
{
private static int a;
private static int r;
private static int g;
private static int b;
private static final double bitPerColor = 4.0;
public static void main(String[] args) throws IOException
{
FileInputStream image = null;
FileInputStream image2 = null;
getPixelData1 newPD = new getPixelData1();
try {
BufferedImage img, img2;
File file = new File("img0.jpg");
File file2 = new File("imgstega.jpg");
image = new FileInputStream(file);
image2 = new FileInputStream(file2);
img = ImageIO.read(image);
img2 = ImageIO.read(image2);
int rowcol;
int width = img.getWidth();
int height = img.getHeight();
System.out.println("Image's Width: " + width);
System.out.println("Image's Height: " + height);
int[][] pixelData = new int[width * height][3];
System.out.println("Pixel Data: " + pixelData);
int[] rgb;
int count = 0;
for(int i=0; i<width; i++)
{
for(int j=0; j<height; j++)
{
rgb = newPD.getPixelData(img, i, j);
for(int k = 0; k < rgb.length; k++)
{
pixelData[count][k] = rgb[k];
}
count++;
System.out.println("\nRGB Counts: " + count);
}
}
int width2 = img2.getWidth();
int height2 = img2.getHeight();
System.out.println("Image's Width: " + width2);
System.out.println("Image's Height: " + height2);
int[][] pixelData2 = new int[width2 * height2][3];
int[] rgb2;
int counter = 0;
for(int i=0; i<width2; i++)
{
for(int j=0; j<height2; j++)
{
rgb2 = newPD.getPixelData(img2, i, j);
for(int k = 0; k < rgb2.length; k++)
{
pixelData2[counter][k] = rgb2[k];
}
counter++;
System.out.println("\nRGB2 Counts: " + counter);
}
}
} catch (FileNotFoundException ex) {
Logger.getLogger(getPixelRGB1.class.getName()).log(Level.SEVERE, null, ex);
} finally {
try {
image.close();
} catch (IOException ex) {
Logger.getLogger(getPixelRGB1.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
}
//1ST PROCESS - Get RGB Pixel Values
public class getPixelData1
{
private static final double bitPerColor = 4.0;
public int[] getPixelData(BufferedImage img, int w, int h) throws IOException
{
int argb = img.getRGB(w, h);
int rgb[] = new int[]
{
(argb >> 16) & 0xff, //red
(argb >> 8) & 0xff, //green
(argb ) & 0xff //blue
};
int red = rgb[0];
int green = rgb[1]; //RGB Value in Decimal
int blue = rgb[2];
System.out.println("\nRGBValue in Decimal --> " + "\nRed: " + red + " Green: " + green + " Blue: " + blue);
//Convert each channel RGB to Hexadecimal value
String rHex = Integer.toHexString((int)(red));
String gHex = Integer.toHexString((int)(green));
String bHex = Integer.toHexString((int)(blue));
System.out.println("\nRGBValue in Hexa --> " + "\nRed Green Blue " + rHex + gHex + bHex);
//Check position 2 and 4 of hexa value for any changes
String hexa2, hexa4 = "";
String rgbHexa = rHex + gHex + bHex;
hexa2 = rgbHexa.substring(1,2);
System.out.println("\nString RGB Hexa: " + rgbHexa);
System.out.println("\nSubstring at position 2: " + hexa2);
String hex = String.format("%02X%02X%02X", red, green, blue);
hexa4 = hex.substring(3,4);
System.out.println("\nSubstring at position 4: " + hexa4);
return rgb;
}
}
//2nd Process - to compare the RGB Hex value of both images
public class compareHexaRGB
{
public int[] compareHexaRGB(BufferedImage img, BufferedImage img2, int w, int h) throws IOException
{
getPixelData1 newPD = new getPixelData1(); //get method from class getPixelData1 - is this correct?
if((img.hexa2.equals(img2.hexa2)) && (img.hexa4.equals(img2.hexa4)))
{
System.out.println("Pixel values at position 2 and 4 are the same.");
}
else if((img.hexa2 != img2.hexa2) || (img.hexa4 != img2.hexa4))
{
System.out.println("Pixel values at position 2 and 4 are not the same.");
}
else if((img.hexa2 != img2.hexa2) && (img.hexa4 != img2.hexa4))
{
System.out.println("Pixel values at position 2 and 4 are not the same.");
}
}
}
The error stated that the program cannot find symbol for hexa2 and hexa4 in bufferedImage. Can someone check whether I've done something wrong with my coding here? I'm still new to Java.

img is of type BufferedImage (javadoc). It does not contain any non-private (nor private) fields named hexa2 or hexa4.
What you need to do is to refactor your code to make sure you have access to them in compareHexaRGB(). There are probably many ways this can be done. Perhaps you could extend BufferedImage to include your fields, or perhaps you could just pass them as input to the method.
Which solution that would be the more elegant one is hard to determine given that we don't really have all your code (for example, I don't see compareHexaRGB() being called at all).
To be more precise about the compilation problem: By using img.hexa2 to access a field, you assume that there is a field called hexa2 in BufferedImage that is accessible from your class. This is true if a field for example is declared as public. More typically, the fields are private scoped and need to be accessed by a getter/setter. For BufferedImage, no such field exists at all.
Learn about access control here.