Class ThresholdOp

java.lang.Object
cloud.opencode.base.image.threshold.ThresholdOp
public final class ThresholdOp extends Object
Fixed Threshold Operations 固定阈值操作工具类

Applies fixed-value thresholding to grayscale images with multiple modes including binary, inverse binary, truncate, to-zero and inverse to-zero.

对灰度图像应用固定值阈值处理，支持多种模式： 二值化、反向二值化、截断、置零和反向置零。

Features | 主要功能:

  • Five threshold modes: BINARY, BINARY_INV, TRUNC, TOZERO, TOZERO_INV - 五种阈值模式
  • LUT-based O(n) implementation - 基于查找表的 O(n) 实现
  • Automatic grayscale conversion - 自动灰度转换

Usage Examples | 使用示例:

// Binary thresholding
Raster binary = ThresholdOp.apply(raster, 128);

// Inverse binary thresholding
Raster inv = ThresholdOp.apply(raster, 128, ThresholdOp.Mode.BINARY_INV);

// Truncate mode
Raster trunc = ThresholdOp.apply(raster, 200, ThresholdOp.Mode.TRUNC);

Performance | 性能特性:

  • Time: O(n) where n = pixel count - 时间: O(n)，n 为像素数量
  • Space: O(n) for output image - 空间: O(n) 用于输出图像

Security | 安全性:

  • Thread-safe: Yes (stateless) - 线程安全: 是（无状态）
Since:
JDK 25, opencode-base-image V2.0.0
Author:
Leon Soo www.LeonSoo.com
See Also:

  • Method Details

    • apply

      public static Raster apply(Raster raster, int threshold, ThresholdOp.Mode mode)
      Apply fixed threshold to a Raster with the specified mode. 使用指定模式对 Raster 应用固定阈值。

      The raster is converted to grayscale using BT.601 luminance, then a lookup table is built according to the mode and applied. The returned raster is always PixelFormat.GRAY_8 regardless of input format.

      使用 BT.601 亮度公式将 raster 转为灰度，然后按模式构建 LUT 并应用。 输出一律为 PixelFormat.GRAY_8。

      Parameters:
      raster - the source raster | 源 raster
      threshold - the threshold value [0, 255] | 阈值 [0, 255]
      mode - the threshold mode | 阈值模式
      Returns:
      the GRAY_8 thresholded raster | GRAY_8 阈值处理后的 raster
      Throws:
      ImageOperationException - if raster is null, threshold out of range, or mode is null
      Since:
      opencode-base-image V1.0.4

    • apply

      public static Raster apply(Raster raster, int threshold)
      Apply BINARY mode threshold to a Raster (convenience method). 对 Raster 应用 BINARY 模式阈值（便捷方法）。
      Parameters:
      raster - the source raster | 源 raster
      threshold - the threshold value [0, 255] | 阈值 [0, 255]
      Returns:
      the GRAY_8 binary thresholded raster | GRAY_8 二值化后的 raster
      Throws:
      ImageOperationException - if raster is null or threshold out of range
      Since:
      opencode-base-image V1.0.4