feat: 完成 Rust 滑块匹配算法，修复透明留白导致的坐标偏移

- 实现灰度与边缘两种匹配模式
- 对齐 OpenCV NCC 算法逻辑
- 优化图像灰度化与 Alpha 通道转换
- 提升坐标计算精度至像素级

src/image_io.rs

@@ -1,6 +1,6 @@
 use anyhow::{Context, Result};
 use base64::{Engine as _, engine::general_purpose};
-use image::{DynamicImage, GenericImageView, ImageBuffer, Rgb, RgbImage};
+use image::{DynamicImage, GenericImageView, ImageBuffer, Luma, Rgb, RgbImage};
 use std::path::{Path, PathBuf};
 use tract_onnx::prelude::tract_ndarray::Array3;
 
@@ -60,3 +60,51 @@ pub fn png_rgba_white_preprocess(img: &DynamicImage) -> DynamicImage {
 
     DynamicImage::ImageRgb8(background)
 }
+
+pub fn image_to_ndarray(img: &DynamicImage) -> Array3<u8> {
+    let (width, height) = img.dimensions();
+
+    // 1. 强制转为 RGB8 (丢弃 Alpha 通道，与 Python 的 target_mode='RGB' 对齐)
+    let rgb_img = img.to_rgb8();
+
+    // 2. 获取原始像素数据
+    let raw_data = rgb_img.into_raw();
+
+    // 3. 构造数组 (通道数改为 3)
+    Array3::from_shape_vec((height as usize, width as usize, 3), raw_data)
+        .expect("Failed to construct ndarray from image") // 建议显式报错，而不是返回全黑图
+}
+#[allow(dead_code)]
+fn save_rust_result(result: &ImageBuffer<Luma<f32>, Vec<f32>>, filename: &str) {
+    let (width, height) = result.dimensions();
+
+    // 1. 寻找最值进行归一化
+    let mut max_val = f32::MIN;
+    let mut min_val = f32::MAX;
+    for p in result.pixels() {
+        if p.0[0] > max_val {
+            max_val = p.0[0];
+        }
+        if p.0[0] < min_val {
+            min_val = p.0[0];
+        }
+    }
+
+    // 2. 创建 8 位灰度图
+    let mut out_buf = ImageBuffer::new(width, height);
+    for y in 0..height {
+        for x in 0..width {
+            let val = result.get_pixel(x, y).0[0];
+            let normalized = if max_val > min_val {
+                ((val - min_val) / (max_val - min_val) * 255.0) as u8
+            } else {
+                0u8
+            };
+            out_buf.put_pixel(x, y, Luma([normalized]));
+        }
+    }
+
+    // 3. 保存
+    DynamicImage::ImageLuma8(out_buf).save(filename).unwrap();
+    println!("Rust 结果热力图已保存至: {}", filename);
+}