I'm working on cracking the codes on the unknowns in the Photoshop namespace. So far I have cracked a few:
photoshop:LayerIDs is very cool. Tag ID 'lyid' https://exiftool.org/TagNames/Photoshop.html#Layers (https://exiftool.org/TagNames/Photoshop.html#Layers)
When you create a layer in Photoshop, it gets an ID of "1" and then goes up. If you DELETE a layer, that ID is removed and never used again. The purpose is to "avoid the case where you add layers, flatten, save, open, and then add more layers that end up with the same IDs as the first set." https://www.adobe.com/devnet-apps/photoshop/fileformatashtml/ (https://www.adobe.com/devnet-apps/photoshop/fileformatashtml/)
I'm pretty sure you can resolve the ID to the layer name by matching its position in the array of photoshop:LayerNames as DocumentData is organized like a struct / array.
photoshop:LayerSelectionIDs is an array of the layers activated in Photoshop. The attachment shows an example where this would be an array containing the layer IDs for "Layer 1" and "Layer 2.'
photoshop:IDsBaseValue is the last ID used, so when the file is open the next Layer ID assigned will be this base value +1.
I'll keep cracking! Anyone out there have anything to share in this namespace? There are a lot of unknowns to decipher.
- J