Orientation field not found after load image and save

[fospring]

This happens in open a image

Expected

Image's Orientation information can be reserved

Actual behaviour

What did happen
But image's Orientation information was discard, and image rotated 180 degrees.

Reproduction steps

extern crate image;
use image::GenericImageView;
fn main() {
    let img = image::open("/tmp/images/origin176.jpeg").unwrap();
    img.save("/tmp/images/176.jpeg").unwrap();
}

the origin image info:

➜  images exiftool origin176.jpeg
ExifTool Version Number         : 12.00
File Name                       : origin176.jpeg
Directory                       : .
File Size                       : 6.3 MB
File Modification Date/Time     : 2020:11:18 16:20:20+08:00
File Access Date/Time           : 2020:11:18 16:21:16+08:00
File Inode Change Date/Time     : 2020:11:18 16:24:07+08:00
File Permissions                : rw-------
File Type                       : JPEG
File Type Extension             : jpg
MIME Type                       : image/jpeg
Exif Byte Order                 : Big-endian (Motorola, MM)
Orientation                     : Rotate 180

The origin image has Orientation field

output image info:

➜  images exiftool 176.jpeg
ExifTool Version Number         : 12.00
File Name                       : 176.jpeg
Directory                       : .
File Size                       : 1496 kB
File Modification Date/Time     : 2020:11:18 16:24:41+08:00
File Access Date/Time           : 2020:11:18 16:26:18+08:00
File Inode Change Date/Time     : 2020:11:18 16:24:41+08:00
File Permissions                : rw-r--r--
File Type                       : JPEG
File Type Extension             : jpg
MIME Type                       : image/jpeg

And the output image info don't have Orientation field so my image was rotated 180 degree

[fintelia]

I think we're a long way from being able to retain EXIF information (see #1045). A more likely short term goal might be to apply the orientation transform when loading the JPEG, but I wonder whether that might also produce surprising results for some users if they for instance load an image with orientation 90 and discover that width an height are swapped?

[fospring]

Yes. Image-rs seems not method to get the Orientation, it's inconvenient to rotate image before compress a image.