Switch score algorithm vom NCC to SSIM to prevent triggers when content moves

Also reduced threshold to 0.9

Author: iComputerfreak

Shared/Sources/Shared/JFLiterals.swift

@@ -66,12 +66,12 @@ public let kPythonPath = "/usr/bin/python3"
 public let kConvertPath = "/usr/bin/convert"
 
 /// The file containing the ncc information
-public let kNccFile = "ncc"
+public let kScoreFile = "ncc"
 /// The filename of the file containing the visual diff representation
 public let kDiffFile = "diff.png"
 
-/// The threshold value the bot uses. If the NCC value is below this, a notification is triggered
-public let kNccThreshold = 0.999
+/// The threshold value the bot uses. If the SSIM value is below this, a notification is triggered
+public let kComparisonThreshold = 0.9
 /// The duration for which a screenshot capture error has to persist for the user to be notified. Set to 0 to immediately notify on errors
 public let kErrorReportDuration: TimeInterval = 120 * 60 // 2 hours
 /// The string used to separate the values in the urls.list file

urlwatcher/Sources/urlwatcher/Functions.swift

@@ -231,25 +231,25 @@ func rollBack(_ oldImage: String, to latestImage: String) throws {
 }
 
 // Calculates the normalized cross-correlation
-func screenshotNCC(_ oldImage: String, _ latestImage: String, diffFile: String) throws -> Double? {
-    let nccPipe = Pipe()
+func screenshotScore(_ oldImage: String, _ latestImage: String, diffFile: String) throws -> Double? {
+    let pipe = Pipe()
     let result = try bash("compare", arguments: [
         "-quiet",
         "-alpha", "deactivate",
-        "-metric", "NCC",
+        "-metric", "SSIM",
         oldImage,
         latestImage,
         diffFile
-    ], standardOutput: nccPipe, standardError: nccPipe)
+    ], standardOutput: pipe, standardError: pipe)
 
-    let nccData = nccPipe.fileHandleForReading.readDataToEndOfFile()
-    guard let nccString = String(data: nccData, encoding: .utf8) else {
+    let scoreData = pipe.fileHandleForReading.readDataToEndOfFile()
+    guard let scoreString = String(data: scoreData, encoding: .utf8) else {
         return nil
     }
 
     // If the images are different-sized, we don't need to treat this as an error.
-    // Instead, we just notify the user about it by setting the NCC to 0
-    if nccString.contains("compare: image widths or heights differ") {
+    // Instead, we just notify the user about it by setting the score to 0
+    if scoreString.contains("compare: image widths or heights differ") {
         return 0
     }
 
@@ -260,7 +260,7 @@ func screenshotNCC(_ oldImage: String, _ latestImage: String, diffFile: String)
         return nil
     }
 
-    return Double(nccString)
+    return Double(scoreString)
 }
 
 func checkUnmute(_ entry: inout URLEntry) throws -> Bool {

urlwatcher/Sources/urlwatcher/main.swift

@@ -152,17 +152,17 @@ do {
 
         let tempDiff = "\(entryPath)/diff.temp"
 
-        guard let ncc = try screenshotNCC(oldImage, latestImage, diffFile: tempDiff) else {
-            print("Error checking screenshot NCC.")
+        guard let score = try screenshotScore(oldImage, latestImage, diffFile: tempDiff) else {
+            print("Error checking screenshot score.")
             try handleScreenshotError(entry: entry)
             try rollBack(oldImage, to: latestImage)
             // Continue with the next entry
             continue
         }
 
         // If the website changed
-        if ncc < kNccThreshold {
-            print("Possible change detected (NCC: \(ncc)). Confirming...")
+        if score < kComparisonThreshold {
+            print("Possible change detected (score: \(score)). Confirming...")
 
             // Take another screenshot to confirm its not just a one-time loading error or inconsistency
             // Delete the changed screenshot, otherwise we cannot confirm that taking the screenshot was a success
@@ -173,18 +173,18 @@ do {
                 continue
             }
 
-            guard let newNCC = try screenshotNCC(oldImage, latestImage, diffFile: tempDiff) else {
+            guard let newScore = try screenshotScore(oldImage, latestImage, diffFile: tempDiff) else {
                 // Error while confirming screenshot
-                print("Error confirming screenshot NCC.")
+                print("Error confirming screenshot score.")
                 try handleScreenshotError(entry: entry)
                 try rollBack(oldImage, to: latestImage)
                 // Continue with the next entry
                 continue
             }
 
-            if newNCC < kNccThreshold {
+            if newScore < kComparisonThreshold {
                 // If the second screenshot also shows changes, we notify the user
-                print("Change confirmed. NCC: \(newNCC). Notifying user.")
+                print("Change confirmed. Score: \(newScore). Notifying user.")
 
                 // Save the temp file persistently
                 let diffFile = "\(entryPath)/\(kDiffFile)"
@@ -197,27 +197,28 @@ do {
                     try fileManager.moveItem(atPath: tempDiff, toPath: diffFile)
                 }
 
-                // Generate detailed NCC information
-                let nccFile = "\(entryPath)/\(kNccFile)"
-                if fileManager.fileExists(atPath: nccFile) {
-                    try fileManager.removeItem(atPath: nccFile)
+                // Generate detailed score information
+                let scoreFile = "\(entryPath)/\(kScoreFile)"
+                if fileManager.fileExists(atPath: scoreFile) {
+                    try fileManager.removeItem(atPath: scoreFile)
                 }
+                // TODO: Duplicated in Functions.swift
                 try bash("compare", arguments: [
                     "-verbose",
                     "-alpha", "deactivate",
-                    "-metric", "NCC",
+                    "-metric", "SSIM",
                     oldImage,
                     latestImage,
                     "/dev/null"
-                ], standardOutput: FileHandle(forWritingAtPath: nccFile))
+                ], standardOutput: FileHandle(forWritingAtPath: scoreFile))
 
                 // Notify the user
-                try sendTelegramMessage("\(entry.name) has changed. NCC: \(ncc)\(ncc != newNCC ? ", \(newNCC)" : "")", to: Int(entry.chatID), image: latestImage)
+                try sendTelegramMessage("\(entry.name) has changed. Score: \(score)\(score != newScore ? ", \(newScore)" : "")", to: Int(entry.chatID), image: latestImage)
             } else {
-                print("Change not confirmed. NCC: \(newNCC)")
+                print("Change not confirmed. Score: \(newScore)")
             }
         } else {
-            print("No change detected. NCC: \(ncc)")
+            print("No change detected. Score: \(score)")
         }
 
         // Clean up any temp diff files