努力設置灰度圖像的平均亮度

Question

我在通過 JUnit 測試時遇到問題，我知道該測試已正確實施，但我不確定它失敗的原因。 下面的代碼應該抓取每個像素（像素 = 數組 exe 中的一個點：2dArray[0][0]）。 每個像素都有一個亮度值，我的方法的目標是將整個陣列中的每個像素亮度值更改為 127 或至少接近它。

下面是我似乎無法通過的有問題的 JUnit 測試以及 JUnit 測試正在測試的方法的當前代碼。 下面的方法將通過大多數 JUnit 測試，但在運行 JUnit 測試的 assertEquals() 部分時失敗。 現在，當我使用 System.out.println() 和 normalizedImage.averageBrightness() 時，它是正確的，並表示圖像的平均亮度為 127 或接近它。 我覺得這很奇怪，現在已經研究這個問題很長一段時間了，我不確定還能嘗試什么。 任何幫助，將不勝感激。

JUnit 測試：

@Test
    void normalized() {
        var smallNorm = smallSquare.normalized();
        assertEquals(smallNorm.averageBrightness(), 127, 127 * .001);
        var scale = 127 / 2.5;
        var expectedNorm = new GrayscaleImage(new double[][] { { scale, 2 * scale }, { 3 * scale, 4 * scale } });
        for (var row = 0; row < 2; row++) {
            for (var col = 0; col < 2; col++) {
                assertEquals(smallNorm.getPixel(col, row), expectedNorm.getPixel(col, row), expectedNorm.getPixel(col, row) * .001, "pixel at row: " + row + " col: " + col + " incorrect");
            }
        }
    }

我當前的代碼：

   /**
     * Return a new GrayScale image where the average new average brightness is 127
     * To do this, uniformly scale each pixel (ie, multiply each imageData entry by the same value)
     * Due to rounding, the new average brightness will not be 127 exactly, but should be very close
     * The original image should not be modified
     * @return a GrayScale image with pixel data uniformly rescaled so that its averageBrightness() is 127
     */
    public GrayscaleImage normalized() {
        // First we make a 2D array that is the same size as the original image.
        double[][] normalized2DArray = new double[imageData[0].length][imageData.length];
        
        // Then we figure out what we need to multiple the pixel by to make sure our average brightness is equal to 127
        double scaleFactor = 127 / averageBrightness();
        
        // Then we will set the brightness of the specified pixel below.
        for (int y = 0; y < imageData[0].length; y++) {
            for (int x = 0; x < imageData.length; x++) {
                 double newPixelValue = getPixel(y, x) * scaleFactor;
                 normalized2DArray[y][x] = newPixelValue;
            }
        }
        
        // We will then turn the 2DArray into a GrayscaleImage
        GrayscaleImage normalizedImage = new GrayscaleImage(normalized2DArray);
        System.out.println(normalizedImage.averageBrightness());
        
        return normalizedImage;
    }

下面是JUnit測試的當前output：

Answer 1

我能夠修復我的代碼問題是 normalized2DArray[y][x] = newPixelValue; 實際上應該是 normalized2DArray[x][y] = newPixelValue;