Class HistogramEqualizationOp

java.lang.Object
cloud.opencode.base.image.histogram.HistogramEqualizationOp
public final class HistogramEqualizationOp extends Object
Histogram Equalization Operations 直方图均衡化操作工具类

Provides histogram equalization for grayscale and color images. Grayscale equalization uses a CDF-based lookup table; color equalization converts to HSV and equalizes only the V (value/brightness) channel.

提供灰度图像和彩色图像的直方图均衡化。 灰度均衡化使用基于 CDF 的查找表；彩色均衡化转换为 HSV 并仅均衡 V（亮度）通道。

Features | 主要功能:

  • Grayscale histogram equalization via LUT - 通过查找表实现灰度直方图均衡化
  • Color histogram equalization via HSV V-channel - 通过 HSV V 通道实现彩色直方图均衡化

Usage Examples | 使用示例:

BufferedImage equalized = HistogramEqualizationOp.apply(grayImage);
BufferedImage colorEqualized = HistogramEqualizationOp.applyColor(colorImage);

Performance | 性能特性:

  • Time complexity: O(w * h) - 时间复杂度: O(w * h)
  • Space complexity: O(w * h) for output image - 空间复杂度: O(w * h) 输出图像

Security | 安全性:

  • Thread-safe: Yes (stateless) - 线程安全: 是（无状态）
  • Null-safe: No - 空值安全: 否
Since:
JDK 25, opencode-base-image V2.0.0
Author:
Leon Soo www.LeonSoo.com
See Also:

  • Method Details

    • apply

      public static BufferedImage apply(BufferedImage image)
      Apply histogram equalization to a grayscale image. 对灰度图像应用直方图均衡化。

      Algorithm: compute histogram, build CDF, create LUT where LUT[i] = round(CDF[i] * 255 / totalPixels), then apply via LookupTableOp.

      算法：计算直方图，构建 CDF，创建查找表 LUT[i] = round(CDF[i] * 255 / totalPixels)，然后通过 LookupTableOp 应用。

      Parameters:
      image - the source image | 源图像
      Returns:
      the equalized image | 均衡化后的图像
      Throws:
      NullPointerException - if image is null | 当图像为 null 时抛出

    • applyColor

      public static BufferedImage applyColor(BufferedImage image)
      Apply histogram equalization to a color image via HSV V-channel. 通过 HSV V 通道对彩色图像应用直方图均衡化。

      Algorithm: convert RGB to HSV, equalize the V channel histogram, convert HSV back to RGB. Hue and Saturation are preserved.

      算法：将 RGB 转换为 HSV，均衡化 V 通道直方图， 将 HSV 转换回 RGB。色相和饱和度保持不变。

      Parameters:
      image - the source color image | 源彩色图像
      Returns:
      the equalized color image | 均衡化后的彩色图像
      Throws:
      NullPointerException - if image is null | 当图像为 null 时抛出