Here is an example of setting per layer metadata.
N.B. To use per layer metadata it must be the active layer!
It uses an external library
[code]
setCommentMetadata("This is a comment");
function setCommentMetadata(comm){
if (ExternalObject.AdobeXMPScript == undefined) ExternalObject.AdobeXMPScript = new ExternalObject("lib:AdobeXMPScript");
if( app.activeDocument.activeLayer.isBackgroundLayer){
alert( "Can not place metadata on a background layer." );
return;
}
try{
xmp = new XMPMeta( app.activeDocument.activeLayer.xmpMetadata.rawData );
} catch( e ) {
xmp = new XMPMeta();
}
try{
xmp.setProperty( XMPConst.NS_EXIF, "userComment", comm );
} catch( e ) {
alert( "Unable to place metadata on selected layer.\n" + e );
}
app.activeDocument.activeLayer.xmpMetadata.rawData = xmp.serialize();
};
[/code]
There is not much difference to get/set of the documents xmp
[code]
if (ExternalObject.AdobeXMPScript == undefined) ExternalObject.AdobeXMPScript = new ExternalObject("lib:AdobeXMPScript");
var xmp = new XMPMeta(activeDocument.xmpMetadata.rawData);
xmp.deleteProperty(XMPConst.NS_XMP, "Label");
xmp.setProperty(XMPConst.NS_XMP, "Label","Approved");
app.activeDocument.xmpMetadata.rawData = xmp.serialize();
[/code]
In Photoshop there are a few fields that you can get/set via DOM
[code]
app.activeDocument.info.author
app.activeDocument.info.caption
app.activeDocument.info.captionWriter
app.activeDocument.info.headline
app.activeDocument.info.instructions
app.activeDocument.info.keywords
app.activeDocument.info.author
app.activeDocument.info.authorPosition
app.activeDocument.info.credit
app.activeDocument.info.source
app.activeDocument.info.category
app.activeDocument.info.supplementalCategories
app.activeDocument.info.title
app.activeDocument.info.creationDate
app.activeDocument.info.city
app.activeDocument.info.provinceState
app.activeDocument.info.country
app.activeDocument.info.transmissionReference
app.activeDocument.info.copyrightNotice
app.activeDocument.info.ownerUrl
//Note keywords is an array
app.activeDocument.info.keywords = ["Keyword1","Keyword 2","Etc"];
[/code]
You can access any schema in the document or layer metadata, they are the same. You can also create you own schema, as an example see this old script of mine:-
https://raw.githubusercontent.com/Paul-Riggott/PS-Scripts/master/GuideSets.jsx
Let me know if you want details of get/set without opening a file.
All these methods use the External Library.
You might be able to invoke the library by doing a "doJavaScript" function if it exists in Python?
