Getting Pixel Array From Image in Java (#13911)

* Added the code for "Getting Pixel Array From Image in Java".

* The code and resources for "Getting Pixel Array From Image in Java".

* Removed the previous files from the wrong module.

algorithms-modules/algorithms-miscellaneous-7/src/main/java/com/baeldung/algorithms/pixelarray/GetPixelArray.java

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+package com.baeldung.algorithms.pixelarray;
+
+import java.awt.image.BufferedImage;
+import java.awt.image.DataBufferByte;
+public class GetPixelArray {
+
+    public static int[][] get2DPixelArraySlow(BufferedImage sampleImage) {
+        int width = sampleImage.getWidth();
+        int height = sampleImage.getHeight();
+        int[][] result = new int[height][width];
+
+        for (int row = 0; row < height; row++) {
+            for (int col = 0; col < width; col++) {
+                result[row][col] = sampleImage.getRGB(col, row);
+            }
+        }
+
+        return result;
+    }
+
+    public static int[][] get2DPixelArrayFast(BufferedImage image) {
+        final byte[] pixelData = ((DataBufferByte) image.getRaster().getDataBuffer()).getData();
+        final int width = image.getWidth();
+        final int height = image.getHeight();
+        final boolean hasAlphaChannel = image.getAlphaRaster() != null;
+
+        int[][] result = new int[height][width];
+        if (hasAlphaChannel) {
+            final int numberOfValues = 4;
+            for (int valueIndex = 0, row = 0, col = 0; valueIndex + numberOfValues - 1 < pixelData.length; valueIndex += numberOfValues) {
+                // Getting the values for each pixel from the pixelData array.
+                int argb = 0;
+                argb += (((int) pixelData[valueIndex] & 0xff) << 24); // alpha value
+                argb += ((int) pixelData[valueIndex + 1] & 0xff); // blue value
+                argb += (((int) pixelData[valueIndex + 2] & 0xff) << 8); // green value
+                argb += (((int) pixelData[valueIndex + 3] & 0xff) << 16); // red value
+                result[row][col] = argb;
+
+                col++;
+                if (col == width) {
+                    col = 0;
+                    row++;
+                }
+            }
+        } else {
+            final int numberOfValues = 3;
+            for (int valueIndex = 0, row = 0, col = 0; valueIndex + numberOfValues - 1 < pixelData.length; valueIndex += numberOfValues) {
+                int argb = 0;
+                argb += -16777216; // 255 alpha value (fully opaque)
+                argb += ((int) pixelData[valueIndex] & 0xff); // blue value
+                argb += (((int) pixelData[valueIndex + 1] & 0xff) << 8); // green value
+                argb += (((int) pixelData[valueIndex + 2] & 0xff) << 16); // red value
+                result[row][col] = argb;
+
+                col++;
+                if (col == width) {
+                    col = 0;
+                    row++;
+                }
+            }
+        }
+
+        return result;
+    }
+}

algorithms-modules/algorithms-miscellaneous-7/src/test/java/com/baeldung/algorithms/pixelarray/GetPixelArrayUnitTest.java

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+package com.baeldung.algorithms.pixelarray;
+
+import static com.baeldung.algorithms.pixelarray.GetPixelArray.get2DPixelArrayFast;
+import static com.baeldung.algorithms.pixelarray.GetPixelArray.get2DPixelArraySlow;
+import static org.junit.Assert.*;
+
+import org.junit.Test;
+
+import javax.imageio.ImageIO;
+import java.awt.image.BufferedImage;
+import java.io.File;
+import java.io.IOException;
+import java.util.Arrays;
+
+public class GetPixelArrayUnitTest {
+    @Test
+    public void givenImage_whenGetPixelArray_thenBothMethodsReturnEqualValues() {
+        BufferedImage sampleImage = null;
+        try {
+            sampleImage = ImageIO.read(new File("src/main/resources/images/sampleImage.jpg"));
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+
+        int[][] firstResult = get2DPixelArraySlow(sampleImage);
+        int[][] secondResult = get2DPixelArrayFast(sampleImage);
+
+        assertTrue(Arrays.deepEquals(firstResult, secondResult));
+    }
+}