Image transformation with no compression/resizing looses quality

When reading and jpeg image from file and writing it back to a different file without applying any transformations it loses size. Example:

sharp('original.jpg').withMetadata().toFile('transformed.jpg');

During the tranformation output is following:

vips warning: exif: bad exif meta "exif-ifd3-GPSVersionID"

The version or sharp that is being used: v0.20.7 file output:

file *.jpg
original.jpg:    JPEG image data, Exif standard: [TIFF image data, big-endian, direntries=16, height=3968, bps=0, width=2976], baseline, precision 8, 2976x3968, frames 3
transformed.jpg: JPEG image data, JFIF standard 1.01, aspect ratio, density 1x1, segment length 16, Exif Standard: [TIFF image data, big-endian, direntries=15, height=3968, bps=0, width=2976], baseline, precision 8, 2976x3968, frames 3

The image that is being transformed original.jpg: Transformed image transformed.jpg: Node versoin: v8.11.4 OS: Ubuntu 18.04

Is this an expected behavior? What options could be specified to avoid any transformatios but still use sharp for writing the output file (this is needed due to specifics of wrapper library implementation)?

[naz]

@lovell thanks! that approach worked, but as @rodrigoalviani mentioned it makes the image that is to be processed bigger size than it initially was. The use case for this processing was an image uploader in Ghost (https://github.com/TryGhost/Ghost/pull/9837). Initially, the idea was to allow configuring compression level and metadata stripping, but we decided to go with defaults that sharp uses as they are just the right ones we wanted in place. Because quality/compression configuration is so different between jpeg, png, webp etc. The more granular configuration will be available if users find a need for it eventually. Cheers!

[rodrigoalviani]

On the mostly cases, 100% quality increases original file size. 95% could be enough.