diff --git a/toonz/sources/include/toonz/Naa2TlvConverter.h b/toonz/sources/include/toonz/Naa2TlvConverter.h
index e15fd38..29627d3 100644
--- a/toonz/sources/include/toonz/Naa2TlvConverter.h
+++ b/toonz/sources/include/toonz/Naa2TlvConverter.h
@@ -146,12 +146,13 @@ public:
       return -1;
   }
 
-  TToonzImageP makeTlv(bool transparentSyntheticInks,
-                       bool removeUnusedStyles = false);
+  TToonzImageP makeTlv(bool transparentSyntheticInks, QList<int> &usedStyleIds);
 
   TVectorImageP vectorize(const TToonzImageP &ti);
   TVectorImageP vectorize(const TRaster32P &ras);
   TVectorImageP vectorize();
+
+  void removeUnusedStyles(const QList<int> &styleIds);
 };
 
 #endif
diff --git a/toonz/sources/toonz/convertpopup.cpp b/toonz/sources/toonz/convertpopup.cpp
index 7ed582e..ae61abf 100644
--- a/toonz/sources/toonz/convertpopup.cpp
+++ b/toonz/sources/toonz/convertpopup.cpp
@@ -784,6 +784,7 @@ void ConvertPopup::setFiles(const std::vector<TFilePath> &fps) {
   // if (m_unpaintedFolder->getPath()==SameAsPainted)
   //   m_unpaintedFolder->setPath(toQString(fps[0].getParentDir()));
   m_palettePath->setPath(CreateNewPalette);
+  m_removeUnusedStyles->setEnabled(false);
 
   // m_fileFormat->setCurrentIndex(areFullcolor?0:m_fileFormat->findText("tif"));
 }
diff --git a/toonz/sources/toonzlib/Naa2TlvConverter.cpp b/toonz/sources/toonzlib/Naa2TlvConverter.cpp
index d0a5e6e..50004f5 100644
--- a/toonz/sources/toonzlib/Naa2TlvConverter.cpp
+++ b/toonz/sources/toonzlib/Naa2TlvConverter.cpp
@@ -331,8 +331,7 @@ void Naa2TlvConverter::computeLinks() {
 
 //-----------------------------------------------------------------------------
 
-// find background regions :
-// (almost) white, touching image border
+// find background regions : (almost) white
 //
 void Naa2TlvConverter::findBackgroundRegions() {
   if (!m_regionRas || m_regions.empty()) return;
@@ -358,11 +357,8 @@ void Naa2TlvConverter::findBackgroundRegions() {
   }
 
   for (int i = 0; i < m_regions.count(); i++) {
-    RegionInfo &region = m_regions[i];
-    if (region.colorIndex == bgColorIndex && region.links.contains(-1)) {
-      region.type = RegionInfo::Background;
-      ;
-    }
+    RegionInfo &region                                 = m_regions[i];
+    if (region.colorIndex == bgColorIndex) region.type = RegionInfo::Background;
   }
 }
 
@@ -1006,7 +1002,7 @@ int Naa2TlvConverter::measureThickness(int x0, int y0) {
 //-----------------------------------------------------------------------------
 
 TToonzImageP Naa2TlvConverter::makeTlv(bool transparentSyntheticInks,
-                                       bool removeUnusedStyles) {
+                                       QList<int> &usedStyleIds) {
   if (!m_valid || m_colors.empty() || m_regions.empty() || !m_regionRas)
     return TToonzImageP();
   int lx                = m_regionRas->getLx();
@@ -1031,27 +1027,13 @@ TToonzImageP Naa2TlvConverter::makeTlv(bool transparentSyntheticInks,
       cs = palette->getStyle(styleId);
     }
     styleIds.append(styleId);
+    if (!usedStyleIds.contains(styleId)) usedStyleIds.append(styleId);
   }
   styleIds.append(0);  // syntetic ink
 
   // int synteticInkStyleId = palette->getPage(0)->addStyle(TPixel32(0,0,0,0));
   // styleIds.append(synteticInkStyleId);
 
-  // Remove unused styles from input palette
-  if (removeUnusedStyles) {
-    for (int p = palette->getPageCount() - 1; p >= 0; p--) {
-      TPalette::Page *page = palette->getPage(p);
-      for (int s = page->getStyleCount() - 1; s >= 0; s--) {
-        int styleId = page->getStyleId(s);
-        if (styleId == -1) continue;
-        // check if the style is used or not
-        if (!styleIds.contains(styleId)) page->removeStyle(s);
-      }
-      // erase empty page
-      if (page->getStyleCount() == 0) palette->erasePage(p);
-    }
-  }
-
   for (int y = 0; y < ly; y++) {
     unsigned short *workScanLine = m_regionRas->pixels(y);
     TPixelCM32 *outScanLine      = ras->pixels(y);
@@ -1115,3 +1097,21 @@ TVectorImageP Naa2TlvConverter::vectorize(const TToonzImageP &ti) {
   vi->setPalette(palette);
   return vi;
 }
+
+//-----------------------------------------------------------------------------
+
+void Naa2TlvConverter::removeUnusedStyles(const QList<int> &styleIds) {
+  // Remove unused styles from input palette
+  if (!m_palette) return;
+  for (int p = m_palette->getPageCount() - 1; p >= 0; p--) {
+    TPalette::Page *page = m_palette->getPage(p);
+    for (int s = page->getStyleCount() - 1; s >= 0; s--) {
+      int styleId = page->getStyleId(s);
+      if (styleId == -1) continue;
+      // check if the style is used or not
+      if (!styleIds.contains(styleId)) page->removeStyle(s);
+    }
+    // erase empty page
+    if (page->getStyleCount() == 0) m_palette->erasePage(p);
+  }
+}
diff --git a/toonz/sources/toonzlib/tcenterlinevectorizer.cpp b/toonz/sources/toonzlib/tcenterlinevectorizer.cpp
index 5db93d7..65992fd 100644
--- a/toonz/sources/toonzlib/tcenterlinevectorizer.cpp
+++ b/toonz/sources/toonzlib/tcenterlinevectorizer.cpp
@@ -176,7 +176,8 @@ TVectorImageP VectorizerCore::centerlineVectorize(
       converter.process(ras32);
       converter.setPalette(palette);
 
-      if (ti = converter.makeTlv(true))  // Transparent synthetic inks
+      QList<int> dummy;
+      if (ti = converter.makeTlv(true, dummy))  // Transparent synthetic inks
       {
         image = ti;
         ras   = ti->getRaster();
diff --git a/toonz/sources/toonzqt/imageutils.cpp b/toonz/sources/toonzqt/imageutils.cpp
index 06b67b6..8131c32 100644
--- a/toonz/sources/toonzqt/imageutils.cpp
+++ b/toonz/sources/toonzqt/imageutils.cpp
@@ -652,6 +652,8 @@ void convertNaa2Tlv(const TFilePath &source, const TFilePath &dest,
   Naa2TlvConverter converter;
   converter.setPalette(palette);
 
+  QList<int> usedStyleIds({0});
+
   int f, fCount = int(frames.size());
   for (f = 0; f != fCount; ++f) {
     if (frameNotifier->abortTask()) break;
@@ -672,8 +674,8 @@ void convertNaa2Tlv(const TFilePath &source, const TFilePath &dest,
 
       converter.process(raster);
 
-      if (TToonzImageP dstImg = converter.makeTlv(
-              false, removeUnusedStyles))  // Opaque synthetic inks
+      if (TToonzImageP dstImg =
+              converter.makeTlv(false, usedStyleIds))  // Opaque synthetic inks
       {
         if (converter.getPalette() == 0)
           converter.setPalette(dstImg->getPalette());
@@ -693,6 +695,8 @@ void convertNaa2Tlv(const TFilePath &source, const TFilePath &dest,
 
     frameNotifier->notifyFrameCompleted(100 * (f + 1) / frames.size());
   }
+
+  if (removeUnusedStyles) converter.removeUnusedStyles(usedStyleIds);
 }
 
 //=============================================================================