diff --git a/src/build_job/package.json b/src/build_job/package.json
index 2805d3b..40eeb97 100644
--- a/src/build_job/package.json
+++ b/src/build_job/package.json
@@ -4,7 +4,7 @@
   "description": "Generate a theme.json file from the images' metadata of the working folder.",
   "main": "themeset_builder.js",
   "scripts": {
-    "test": "node themeset_builder.js"
+    "start": "node themeset_builder.js"
   },
   "author": "Simon",
   "license": "ISC",
diff --git a/src/build_job/themeset_builder.js b/src/build_job/themeset_builder.js
index a111c54..5389aad 100644
--- a/src/build_job/themeset_builder.js
+++ b/src/build_job/themeset_builder.js
@@ -7,11 +7,69 @@ const iptc = require('node-iptc');
 // find all images
 const slug = env.PACKAGE_NAME || "valid_set";
 const root = env.ENTRY_FOLDER || "test";
-let file = path.join(root, slug, "bl2_eridum_badlands_1.jpg");
+let workingDirectory = path.join("../..", root, slug);
 
 // extract metadata from them
-fs.readFile(file, function (err, data) {
-	if (err) { throw err }
-	var iptc_data = iptc(data);
-	console.log(iptc_data)
-});
\ No newline at end of file
+fs.readdir(workingDirectory, (err, files) => {
+	if (err) { throw err };
+
+	// construct a JSON file
+	let theme = new Object();
+	theme.dayImageList = [];
+	theme.nightImageList = [];
+	theme.sunsetImageList = [];
+	theme.sunriseImageList = [];
+
+	// iterate each files
+	files.filter(file => path.extname(file) == '.jpg').forEach(image => {
+		buffer = fs.readFileSync(path.join(workingDirectory, image));
+		//if (err) { throw err };
+		// extract metadata
+		let metadata = iptc(buffer);
+		// fill object
+		theme.imageFilename ||= metadata.special_instructions + "_*" + path.extname(image);
+		theme.imageCredits ||= metadata.copyright_notice;
+		theme.displayName ||= metadata.headline;
+		// explore categories to find if image is dayHighlight or nightHighlight
+		metadata.supplemental_categories?.forEach(cat => {
+			switch (cat) {
+				case "dayHighlight":
+					theme.dayHighlight ||= metadata.original_transmission_reference;
+					break;
+				case "nightHighlight":
+					theme.nightHighlight ||= metadata.original_transmission_reference;
+					break;
+				default:
+					break;
+			}
+		});
+
+		switch (metadata.category) {
+			case "day":
+				theme.dayImageList.push(metadata.original_transmission_reference);
+				break;
+			case "night":
+			case "nig":
+				theme.nightImageList.push(metadata.original_transmission_reference);
+				break;
+			case "sunset":
+			case "twilight":
+			case "twi":
+				theme.sunsetImageList.push(metadata.original_transmission_reference);
+				break;
+			case "sunrise":
+			case "dawn":
+			case "daw":
+				theme.sunriseImageList.push(metadata.original_transmission_reference);
+				break;
+			default:
+				break;
+		}
+	});
+
+	fs.writeFileSync(path.join(workingDirectory, 'theme.json'), JSON.stringify(theme));
+});
+
+
+
+