Editing in Photos; what happens under the hood?

In Photos, I am wondering what happens under the hood. There is no history of edits and I've not found proof of sidecar files being used. I can go back all the way to the original raw file, but what I'm really wondering is as I edit the file, click done, edit it again, click done, edit it again, click done, run it through an extension, click done, what actually happens? Does Photos render a JPEG when I click 'done' and open this for further processing when I edit it again? Or can anyone confirm there really is sidecar data happening somewhere?

In Photos is also a kind of editing history, like in Aperture. You can undo the adjustments individually by unchecking the blue checkmarks in the Adjustment panel.

You can also tell that Photos is computing all edits from the original, because the originals need to be available, if you want to edit.

But that is different, if you are using photo editing extensions. In this case a new quasi master will be created and successive edits will be using this quasi master file, just like previously in Aperture, when we used an external editor or a plug-in.

After I use an editing extension, I am seeing an additional large TIFF file in the folder model resources in the Photos Library, even if the original file is a moderately sized JPEG.

I guess the only option then is to develop a photo into its final product before sending it to an extension. And to not use more than one extension?

That is difficult, because the extensions are specialized tools, one extension, one purpose. I usually need two or three extensions at least - for example DxO for the basic development, then Haze Removal, then Noiseless, the Retouch.

I tested again and edited a JPG "defaultdesktop.jpg" with the Affinity Develop editing extension:

I found the following traces in the Photos Library:

~/Pictures/Photos Library Main2.photoslibrary/private/com.apple.Photos/editsession/AA57200A-DA03-4E39-891 F-684E349CAB57.defaultdesktop.jpg

~/Pictures/Photos Library Main2.photoslibrary/Masters/2011/12/14/20111214-152525/DefaultDesktop.jpg

~/Pictures/Photos Library Main2.photoslibrary/Previews/2016/01/19/20160119-151058/tM1+ao4pRCmWhI%du2VNvw/ defaultdesktop.jpg

~/Pictures/Photos Library Main2.photoslibrary/resources/modelresources/100/97/daeeCRocQbiX1m6RzSC8rQ/defa ultdesktop.jpg

~/Pictures/Photos Library Main2.photoslibrary/Thumbnails/2011/12/14/20111214-152525/QutAiWgJTlqJD9E7eXMxS g/thumb_DefaultDesktop.jpg

No XMP files after editing with Affinity Photo Extensions.

But when I search my iCloud Photo Library for XMP files, there are plenty, and some are associated with photos that I edited using MacPhun photo editing extensions. For example, I used MacPhun's Intensify to edit this photo:

There are plenty of XMP files in the Masters folder. But I cannot say, if they are just saving the metadata or also the edits.

But I cannot say, if they are just saving the metadata or also the edits.

Correction. I opened a few of the XMP files in the Masters folder in Xcode, and all of them contained only the metadata that Photos can export, when I use "File > Export > Export Original file" and select to create a sidecar file. The only tags I found in the sidecar files are title, caption, keywords, creator, creation date, usage terms, GPS tags.

And another correction: The originals from my iPhone, mostly panoramic shots, are accompanied by .AAE sidecar files. These sidecar files contain information about the adjustments:

For example:

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">

<plist version="1.0">

<dict>

<key>adjustmentBaseVersion</key>

<integer>0</integer>

<key>adjustmentData</key>

<data>

fZDBTsMwEET/Zc850LRCyDdAqO2lSBTRA+KwqdfJQmxH9rqXqv+OU6NSRYibZzSaN+sj

GB8syhuFyN6BmlVgSVCjIKgjWIxCYUXcdgKqXizuqh9vx1o6UPP6dlGBD0xOUErFqYJD

6Vs748eaJnGvN8k2FEDBrF7N6xlUgMNwAUPWcd+RxRc6cPFuKhh6lHFiDvDzFnI16s8U

xWZeBPV+/OMActj0pEFJSJRbSYRdG8chZAztf8MZUJwNWsqIxy74/MgU1hnAhs+Dn86Z

bP9LM9jHCc4bk+Wrd3RmFbmVQK4dP+9iLQOyu9IbShKwX6K1eGWvUulhNyR56HH/de/0

rmMZ7enorcUwCZ0+Tt8=

</data>

<key>adjustmentEditorBundleID</key>

<string>com.apple.camera</string>

<key>adjustmentFormatIdentifier</key>

<string>com.apple.photo</string>

<key>adjustmentFormatVersion</key>

<string>1.0</string>

</dict>

</plist>

Yes, sometimes I have edited files on the iPhone and the iPad.

Your friend's analogy is like saying if a Porsche is f=good enough for race cars drivers then it is certainly good enough for grandmas Sunday driving

LR is a great program which is hard to learn and hard to use in many ways and far too much program casual users processing snapshots

There is no "best" program - everyone has their own requirements and no one that is the "only" program fro everyone

For me Photos is a great program for me and I consider myself as an above average amateur - OT uses Photos for projects but a different program for management - Terrence uses LR since he does not consider Photos adequate for his needs

Basically the answer is you have to make your decision - there is no perfect program

LN

The highest quality results, I think, would be the result of a piece of software that can take the raw file, and layer every edit on top of that, without using JPEG or TIFF derivatives in between stages.

Most modern programs do that

Photos

iPhoto

Aperture

LightRoom

and on and on and on

And of course your friend correct - even for programs with destructive editing the quality reduction with normal edits is not noticeable -

but with Photos it does not exist as there never is an intermediate image produced - all edits are recorded in the database and applied wehn the image is viewed or exported - there is no resuction of quality with an infinite number of edits - the final version is one and only one step away fro the original (exactly the same for the other programs listed)

LN

FFor the highest quality photos the most important part is taking good photos - a very fast camera that is easy to handle and, Avery good lens, that is sharp across the zoom range, a good sensor without too much noise, a steady hand or a tripod, and the patience to wait for the right moment and the right light. A good photo does not need too much adjusting or effects.

℗ when I take my pictures I am still as careful as when shooting on film.

Oh - and that too 😉 - a poor photo will never be a great photo no matter how many edits are made and a great photos will never be made poor by a few edits and recompressions even with destructive editing

LN