How to save as jp2 not jpf

The following script can be used if all else fails.

It will save as a copy using lossless JP2 compatible settings to the same location as the source file. The file extension will be JPF. If you really wish to use JP2 as the file extension, the placeholder code would need to be uncommented to rename the saved file as Photoshop insists on using JPF, even if JP2 is used as the extension.

var docName = activeDocument.name.replace(/\.[^\.]+$/, '');

try {
	var outputPath = activeDocument.path.fsName;
} catch (e) {
	var outputPath = Folder.selectDialog("Unsaved base file, select the output folder:");
}

var saveFileJPF = new File( outputPath + "/" + docName + ".jpf" );

if (saveFileJPF.exists) {
	// true = 'No' as default active button
	if (!confirm("'" + saveFileJPF.name + "' exists, overwrite: Yes or No?", true))
		// throw alert("Script cancelled!");
		throw null;
}

saveJPF();

/*
var theRegEx = saveFileJPF.name.replace(/\.jpf/, '.jp2');
saveFileJPF.rename(theRegEx);
*/


function saveJPF() {
	function c2t(s) {
		return app.charIDToTypeID(s);
	}
	function s2t(s) {
		return app.stringIDToTypeID(s);
	}
	var descriptor = new ActionDescriptor();
	var descriptor2 = new ActionDescriptor();
	descriptor2.putBoolean( c2t( "JPLS" ), false );
	descriptor2.putBoolean( c2t( "JPFM" ), true );
	descriptor2.putBoolean( c2t( "JPMD" ), true );
	descriptor2.putBoolean( c2t( "JPTP" ), false );
	descriptor2.putBoolean( c2t( "JPJC" ), true ); // ? JP2 ?
	descriptor2.putInteger( c2t( "JPEH" ), 50 );
	descriptor2.putInteger( c2t( "JPPO" ), 0 );
	descriptor2.putBoolean( c2t( "JPCS" ), true );
	descriptor2.putInteger( c2t( "JPWF" ), 0 );
	descriptor2.putInteger( c2t( "JPTS" ), 3 );
	descriptor2.putBoolean( c2t( "JPJX" ), false );
	descriptor2.putBoolean( c2t( "JPXM" ), true );
	descriptor2.putBoolean( c2t( "JPEX" ), true );
	descriptor2.putBoolean( c2t( "JPIP" ), true );
	descriptor2.putBoolean( c2t( "JPRP" ), true ); // ? JP2 ?
	descriptor2.putInteger( c2t( "JPEV" ), 0 );
	descriptor2.putInteger( c2t( "JPIS" ), 1 );
	descriptor2.putInteger( c2t( "JPRS" ), 1 );
	descriptor.putObject( s2t( "as" ), s2t( " JPEG 2000" ), descriptor2 );
	descriptor.putPath( s2t( "in" ), new File( saveFileJPF ) );
	descriptor.putBoolean( s2t( "copy" ), true );
	descriptor.putBoolean( s2t( "lowerCase" ), true );
	executeAction( s2t( "save" ), descriptor, DialogModes.NO );
}

Info on saving and running script code here:

https://prepression.blogspot.com/2017/11/downloading-and-installing-adobe-scripts.html

Try manually changing the extension to jp2 in Save As. When you then click "save" you will see the jp2 compatible box is checked and greyed.

Dave