Class HistogramOp

java.lang.Object
cloud.opencode.base.image.histogram.HistogramOp
public final class HistogramOp extends Object
Histogram Computation Operations 直方图计算操作工具类

Computes histograms for grayscale and color images. Provides per-channel statistics including counts, min, max, and mean values.

计算灰度图像和彩色图像的直方图。提供每个通道的统计信息， 包括计数、最小值、最大值和均值。

Features | 主要功能:

  • Grayscale histogram computation - 灰度直方图计算
  • Per-channel (R, G, B) histogram computation - 逐通道（R、G、B）直方图计算
  • Statistics: min, max, mean per histogram - 统计: 每个直方图的最小值、最大值、均值

Usage Examples | 使用示例:

BufferedImage image = ImageIO.read(new File("photo.png"));
HistogramOp.Histogram gray = HistogramOp.computeGray(image);
System.out.println("Mean: " + gray.mean());

HistogramOp.Histogram[] rgb = HistogramOp.compute(image);
// rgb[0] = Red, rgb[1] = Green, rgb[2] = Blue

Performance | 性能特性:

  • Time complexity: O(w * h) - 时间复杂度: O(w * h)
  • Space complexity: O(256) per histogram - 空间复杂度: 每个直方图 O(256)

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

    • computeGray

      public static HistogramOp.Histogram computeGray(BufferedImage image)
      Compute the grayscale histogram of an image. 计算图像的灰度直方图。

      The image is first converted to grayscale using ITU-R BT.601 coefficients.

      图像首先使用 ITU-R BT.601 系数转换为灰度。

      Parameters:
      image - the source image | 源图像
      Returns:
      the grayscale histogram (channel=0) | 灰度直方图（channel=0）
      Throws:
      NullPointerException - if image is null | 当图像为 null 时抛出

    • compute

      public static HistogramOp.Histogram[] compute(BufferedImage image)
      Compute per-channel (R, G, B) histograms of an image. 计算图像的逐通道（R、G、B）直方图。
      Parameters:
      image - the source image | 源图像
      Returns:
      an array of 3 histograms: [0]=Red(channel=1), [1]=Green(channel=2), [2]=Blue(channel=3) | 3 个直方图数组：[0]=红色(channel=1), [1]=绿色(channel=2), [2]=蓝色(channel=3)
      Throws:
      NullPointerException - if image is null | 当图像为 null 时抛出