Strange thing with sidecar file sizes

Discuss Photomator and photo editing.
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2022-04-13 16:05:47

I know I’ve been mentioning the size of the nondestructive sidecar files being very large, typically into many MBs each (anything from 3x to 8x the original depending on edits).

That was while I had been using iCloud as the storage location for the Pixelmator .edit files.

Now recently I’ve decided that as I never use Pixelmator Photo on any other devices, I switched it to use local storage on my iPad Pro. Still with the intention of deleting them after my editing session is completed on that album.

A weird thing, all these sidecar files are only about 400KB. Yet all the nondestructive workflow is still maintained. So what’s occurring here? Why do these sidecar files have to be so large when saved to the iCloud storage?

Clearly the smaller files are possible, despite information from the developers to the contrary.
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2022-04-14 21:12:35

Hey Andy, can you share your settings? How are you getting small sidecar files?

When I edit a photo from local storage (files app) I get a .photo file that is larger than the original raw file. Both the RAW and the .Photo in the same folder, more than doubling the space they take.
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2022-04-14 21:54:13

Hi Cantisani,
Hey Andy, can you share your settings? How are you getting small sidecar files?
I only changed the settings to stop using iCloud storage for Pixelmator, and switched to local storage on my iPad. As far as I can see there are no other settings that affect the non-destructive sidecar files, they're either on or off.

I really wish I knew what was happening here.
When I edit a photo from local storage (files app) I get a .photo file that is larger than the original raw file. Both the RAW and the .Photo in the same folder, more than doubling the space they take.
I see, no, it's not the photo that's stored locally, only the sidecar file.

I'm editing images from my Photo library in iCloud. Pixelmator can be adjusted to use either iCloud or local storage for its own data, which is separate to the images in the iCloud library. You'll see a folder, using Files, in your iCloud Drive, or On My iPad, called 'Photo' with a nested folder called 'Linked Items', this is where it stores the sidecar files.

In Pixelmator preferences there is a switch to use, or not, iCloud storage (click the little gear icon at the top left, then select 'Editing', then turn off 'Use iCloud').

There is also another setting in the main preferences (under the System Preferences app) that also has 'Documents Storage', but switching this seems to have no effect, so I've no idea what this setting does.

So, I access my Photos library, open the image for editing in Pixelmator using the Photo library browser. When I edited an image with it set to iCloud data storage, it produced huge sidecar files, usually around 90Mb for my 10MB ORF files. I simply switched to using local storage on my iPad (by switching off Use iCloud), and the sidecar files are all around 400KB.

In both cases the final JPEG 'Preview' created for the Photos library is around 15MB. For these I'm applying ML Super Resolution and some basic editing (exposure, colour, sharpen), so the JPEG size is about as expected.

I just don't understand that though. There seems to be no loss of performance, or image quality, but they (Pixelmator developers that is) have insisted that the sidecars can't be reduced.

Now if Pixelmator had created a 400KB sidecar file when using iCloud storage, then I would never need to delete any, and indeed, it would have completely changed my thoughts on my workflow entirely.

As it is, I still don't want to fill up my iPad storage with all these sidecar files, so they're still being deleted after I've done a batch of editing.
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2022-04-15 05:40:37

I see! I’ll try editing from the Photos library and turning off the iCloud storage option.

When the photos are in the Files app, the app duplicates the file but now in the .Photo format, and if you use the clone tool the file size can go up to 100+ Mb, usually 140Mb for my photos. If I just color correct, then the .photo file is about 500k -2Mb larger than the original RAW file. In my case, one photo went from 28.5MB to 29MB, others go a bit larger.

Thanks!
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2022-04-17 21:35:42

How weird, once I switched to local storage, it didn't matter what adjustments I applied, the sidecars were all around 400KB.

It is of course relative to the starting file size, and very much similar to when you save Raw to an uncompressed TIFF.

Most non-destructive editors can manage to save editing data in a small xml/xml type sidecar file, usually only a few KB is needed. Any re-rendering can be done again if needed - OK, it may take a few seconds more, but once edited it's not often a file is revisited (usually!). It's then normal to save a full-res JPEG preview over the original (which is how Photos, and others, do it), to accompany the small xml sidecar file (I believe this is what Photos uses, and Raw Power seems to make use of these within the Photos Library too, and also manages to easily sync them across *all* devices).

I know Lightroom works this way too, with many choices of whether you use JPEGs, TIFFs, or even no previews at all (yes, know it's a premium subscription software package, I'm simply showing that such things are possible).

Of course there are a few that save these huge proprietary sidecar files (Pixelmator, Affinity and Skylum to name some).

However, I'm not sure the reasons they have for these enormous '.edit' files, if it's just a matter of performance, then surely it could be a user choice. All you should need is the adjustment data, and a final image for use in Photos. The large working files could be disposed of, and still maintain the non-destructive workflow.

But all said, in the end, as long as I'm prepared to keep deleting these sidecar files, and lose the non-destructive workflow element, then there is no doubt that Pixelmator represents astonishing great value on an iDevice.