Export the current image from Photos without loss

Filer>Export>Export nn Photos will export the edited, commented, and cropped version in the format and resolution that you choose. This is the "current version," and it will include full metadata that can be shared with other apps.

You get lots of choices. Exporting with "Moment Name" puts pictures taken at about the same time in to the same folders.

Is there some way that this is not what you're wanting?

You can also use File>Export>Export nn Unmodified Originals to get the, well, unmodified originals.

The Photos Library has way more information than either of those exports, so for backups we drag the Photos Library package to an external drive.

You may want to see this:

Basic Concepts and Terms About Photos - Apple Community

A big advantage of the Photos app is its compatibility with iCloud Photos. There's this:

Understanding iCloud Photos - Apple Community

Lennart_T wrote:

In iPhoto, exporting the current version just involved a (fast and simple) file copy. No image processing, no quality loss.

Are you sure iPhoto could losslessly export as .jpg?

Yes, it is possible to crop .jpg losslessly but it requires that crop borders must snap to macroblock boundaries (usually multiples of 8 or 16 pixels). Apps like GraphicConverter can do that.

If you want to export losslessly, choose PNG or TIFF although they are larger than JPEG.

The so-called Modified File there is actually the Preview. That was used for sharing images with other applications. It was a medium quality version of the shot, frequently missing metadata, or at least unreliable in its treatment of metadata. The idea is that this would be shared to email or a word processing document as a "good enough" version of the photograph and save you the bother of exporting every single time you wanted to send a pic somewhere.

Exporting is there to give you more control over the filetypes and quality of your exports.

You have to distinguish between file metadata and photo metadata. They are quite separate things. The file data you refer to is accurate to the extent that it reflects the date these individual files were created. However that has nothing to do with the date the photo was taken, which is preserved in the photo's Exif metadata.

The variation in file size is down to the quality of the jpeg, that is, the amount of compression applied when creating it. Higher quality means larger file sizes. This is why it is quite possible to get exports of a photograph that have a larger file size than the original. Essentially, the app is applying less compression than the camera did, that's all.

Photos is not the same as iPhoto. There is no "modified" version that can be exported. But you can export better quality - or lower quality - options in the File -> Export dialogue. Drag and drop from the Photos window will yield the Preview.

Lennart_T wrote: I only have iPhoto libraries converted to Photos. Dragging from both iPhoto and Photos produces files identical to the "current" export from iPhoto.

For me using the Tahoe, dragging pictures from the Photos Library produces Preview copies that are more compressed than in using Export.

For instance:

For a certain picture on my Mac, the Info Window shows its size  as being 38MB and a dimension of 8245 x 4637 pixels. If I use File>Export, at full size and highest quality, I get the same dimensions but 33MB—so it’s been compressed slightly.  On the other hand, when I use Drag & Drop (today,) I get a size of 13MB at 8245 x 4637, and it looks a bit different--probably from extra jpg compression used in Drag & Drop. I’m not sure what I’d get tomorrow. 

From the article Should you use Drag & Drop in Photos? - Apple Community

In any case, Drag & Drop isn't supported, and how it works may be different in another OS version. There's no documentation on how it works.

Lennart_T wrote: In Photos the jpeg export uncompresses the image and recompresses the image in the format I choose. That causes a (slight) loss in quality.

I'm not sure where you got that. In those articles I linked, it was pointed out that the image was never a file to be compressed or uncompressed. Edits are not stored in an image file-- they are stored in the database. There is no exporting a file "as is" since such a file doesn't exist until you use export.

Compression can have different levels of loss. For jpgs, choose Maximum. If you want an uncompressed file, choose TIFF.

Sorry but I don't speak your language but looking at those screen shots, it seems like these files reside on a server or a NAS? Is that where your library is?

Also, how are you accessing these Modified files? Using File -> Export or accessing them via the Finder or file browser (reveal in Finder)?

Drag an image from the iPhoto window to the desktop, compare that to the Current export. How do they compare?

Then drag the same image from the Photos window. Compare them. How does that compar with the Current export and the dragged version from iPhoto?

If you export as a JPEG and use Maximum Quality for JPEG Quality the file size will be nearly 3 times what the original JPEG file was. Since jpeg is a compressed format it seems to uncompressed it even more than the original was.

Since jpeg is a compressed format it seems to uncompressed it even more than the original was.

OT

I think what goes on there is a bit different from that.

An image is either compressed or uncompressed, it can't be more uncompressed...

Jpeg is a compression format, optimised for images. So within the jpeg is the image file. When you export from Photos (and iPhoto) a copy of the image is put into a new jpeg, and Photos/iPhoto applies compression to that. What you're seeing is that the app is applying less compression on export than the camera did. Hence larger file size or higher jpeg quality.

But the image is the image... just the box that contains it is more or less scrunched to fit the storage.