Why do write_to and save result in different outputs?

[jkoking]

extern crate image;
extern crate leptess;

use image::DynamicImage;
use std::io::Cursor;

pub fn OCR(img: DynamicImage, lang: String) -> String {
    let mut tess = leptess::LepTess::new(None, &lang).unwrap();
    let mut tiff_buffer = Vec::new();
    img.write_to(&mut Cursor::new(&mut tiff_buffer), image::ImageOutputFormat::Tiff).unwrap();
    tess.set_image_from_mem(&tiff_buffer).unwrap();
    let text = tess.get_utf8_text().unwrap();
    if cfg!(debug_assertions) {
        img.save("ocr.tiff").unwrap();
    }
    return text;
}

img.write_to result

usable data for leptess

img.save result

All white fully transparent image

[fintelia]

The two methods should be the same and I don't see anything obviously wrong with your code. If you can provide the failing image, it might be worth filing an issue

[jkoking]

I had to put it in a tar because github doesn't support tiff.
ocr.tiff.tar.gz