高性能快速输出图片ev100值 #photography #image

ev100.rs

#!/bin/env rust-script
//! ```cargo
//! [dependencies]
//! rexif = "0.7.5"
//! serde_json = "1.0.145"
//! ```
use std::env;
use rexif::{ExifTag, TagValue};

fn main() {
    let args: Vec<String> = env::args().collect();
    if args.len() < 2 {
        eprintln!("用法: {} <图片路径>", args[0]);
        std::process::exit(1);
    }
    let file_path = &args[1];

    let exif_data = match rexif::parse_file(file_path) {
        Ok(data) => data,
        Err(e) => {
            eprintln!("错误: 无法解析文件 '{}'。原因: {}", file_path, e);
            std::process::exit(1);
        }
    };

    let mut f_number: Option<f64> = None;
    let mut exposure_time: Option<f64> = None;
    let mut iso: Option<f64> = None;

    for entry in exif_data.entries {
        match entry.tag {
            ExifTag::FNumber => {
                if let TagValue::URational(ref v) = entry.value {
                    if !v.is_empty() {
                        f_number = Some(v[0].numerator as f64 / v[0].denominator as f64);
                    }
                }
            }
            ExifTag::ExposureTime => {
                if let TagValue::URational(ref v) = entry.value {
                    if !v.is_empty() {
                        exposure_time = Some(v[0].numerator as f64 / v[0].denominator as f64);
                    }
                }
            }
            ExifTag::ISOSpeedRatings => {
                match entry.value {
                    TagValue::U16(ref v) if !v.is_empty() => iso = Some(v[0] as f64),
                    _ => {}
                }
            }
            _ => {}
        }
    }

    if let (Some(n), Some(t), Some(s)) = (f_number, exposure_time, iso) {
        let ev_current = (n.powi(2) / t).log2();
        let ev100 = ev_current - (s / 100.0).log2();

        let obj = serde_json::json!({
            "ev100": ev100,
            "path": file_path
        });

        println!("{}", obj);
    } else {
        eprintln!("错误: 图片缺少必要的 EXIF 数据 (光圈、快门或 ISO)。");
        std::process::exit(1);
    }
}