diff --git a/NEWS.md b/NEWS.md
index 7e16f8d502..18255fc69f 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -2,6 +2,7 @@
 
 * JSON format: Fixed tile order when loading a tileset using the old format
 * tmxrasterizer: Added --hide-object and --show-object arguments (by Lars Luz, #3819)
+* Scripting: Made Tileset.margin and Tileset.tileSpacing writable
 * Windows: Fixed the support for WebP images (updated to Qt 6.5.3)
 
 ### Tiled 1.10.2 (4 August 2023)
diff --git a/docs/scripting-doc/index.d.ts b/docs/scripting-doc/index.d.ts
index 002c8e369d..194439b0c6 100644
--- a/docs/scripting-doc/index.d.ts
+++ b/docs/scripting-doc/index.d.ts
@@ -3336,13 +3336,21 @@ declare class Tileset extends Asset {
 
   /**
    * Spacing between tiles in this tileset in pixels.
+   *
+   * @note Changing this property will cause an image-based tileset to update
+   * all its tiles. When setting up a tileset, you'll want to set this property
+   * before setting the {@link image} property.
    */
-  readonly tileSpacing : number
+  tileSpacing : number
 
   /**
    * Margin around the tileset in pixels (only used at the top and left sides of the tileset image).
+   *
+   * @note Changing this property will cause an image-based tileset to update
+   * all its tiles. When setting up a tileset, you'll want to set this property
+   * before setting the {@link image} property.
    */
-  readonly margin : number
+  margin : number
 
   /**
    * The alignment to use for tile objects (when Unspecified, uses Bottom alignment on isometric maps and BottomLeft alignment for all other maps).
diff --git a/src/libtiled/imagereference.cpp b/src/libtiled/imagereference.cpp
index 630de97dca..164c772f42 100644
--- a/src/libtiled/imagereference.cpp
+++ b/src/libtiled/imagereference.cpp
@@ -21,7 +21,6 @@
 #include "imagereference.h"
 
 #include "imagecache.h"
-#include "tileset.h"
 
 namespace Tiled {
 
@@ -33,10 +32,10 @@ bool ImageReference::hasImage() const
 QPixmap ImageReference::create() const
 {
     QPixmap pixmap;
-    if (source.isLocalFile())
-        pixmap = ImageCache::loadPixmap(source.toLocalFile());
-    else if (source.scheme() == QLatin1String("qrc"))
-        pixmap = ImageCache::loadPixmap(QLatin1Char(':') + source.path());
+
+    const QString fileName = Tiled::urlToLocalFileOrQrc(source);
+    if (!fileName.isEmpty())
+        pixmap = ImageCache::loadPixmap(fileName);
     else if (!data.isEmpty())
         pixmap = QPixmap::fromImage(QImage::fromData(data, format));
 
diff --git a/src/libtiled/mapreader.cpp b/src/libtiled/mapreader.cpp
index 6dbb9c0ce1..820eed8b43 100644
--- a/src/libtiled/mapreader.cpp
+++ b/src/libtiled/mapreader.cpp
@@ -307,9 +307,8 @@ std::unique_ptr<Map> MapReaderPrivate::readMap()
         mMap.reset();
     } else {
         // Try to load the tileset images for embedded tilesets
-        auto tilesets = mMap->tilesets();
-        for (SharedTileset &tileset : tilesets) {
-            if (!tileset->isCollection() && tileset->fileName().isEmpty())
+        for (const SharedTileset &tileset : mMap->tilesets()) {
+            if (tileset->fileName().isEmpty())
                 tileset->loadImage();
         }
 
@@ -1501,7 +1500,7 @@ std::unique_ptr<Map> MapReader::readMap(const QString &fileName)
 SharedTileset MapReader::readTileset(QIODevice *device, const QString &path)
 {
     SharedTileset tileset = d->readTileset(device, path);
-    if (tileset && !tileset->isCollection())
+    if (tileset)
         tileset->loadImage();
 
     return tileset;
diff --git a/src/libtiled/mapwriter.cpp b/src/libtiled/mapwriter.cpp
index 63758d2208..2025c5b14a 100644
--- a/src/libtiled/mapwriter.cpp
+++ b/src/libtiled/mapwriter.cpp
@@ -404,12 +404,17 @@ void MapWriterPrivate::writeTileset(QXmlStreamWriter &w, const Tileset &tileset,
     writeProperties(w, tileset.properties());
 
     // Write the image element
-    const QUrl &imageSource = tileset.imageSource();
-    if (!imageSource.isEmpty()) {
+    const bool isCollection = tileset.isCollection();
+    if (!isCollection) {
         w.writeStartElement(QStringLiteral("image"));
-        QString source = toFileReference(imageSource, mUseAbsolutePaths ? QString()
-                                                                        : mDir.path());
-        w.writeAttribute(QStringLiteral("source"), source);
+
+        const QUrl &imageSource = tileset.imageSource();
+        if (!imageSource.isEmpty()) {
+            // Write a reference to an external tileset image
+            QString source = toFileReference(imageSource, mUseAbsolutePaths ? QString()
+                                                                            : mDir.path());
+            w.writeAttribute(QStringLiteral("source"), source);
+        }
 
         const QColor transColor = tileset.transparentColor();
         if (transColor.isValid())
@@ -422,10 +427,22 @@ void MapWriterPrivate::writeTileset(QXmlStreamWriter &w, const Tileset &tileset,
             w.writeAttribute(QStringLiteral("height"),
                              QString::number(tileset.imageHeight()));
 
+        if (imageSource.isEmpty()) {
+            // Write an embedded image
+            w.writeAttribute(QStringLiteral("format"), QLatin1String("png"));
+
+            w.writeStartElement(QStringLiteral("data"));
+            w.writeAttribute(QStringLiteral("encoding"), QLatin1String("base64"));
+
+            QBuffer buffer;
+            tileset.image().save(&buffer, "png");
+            w.writeCharacters(QString::fromLatin1(buffer.data().toBase64()));
+            w.writeEndElement(); // </data>
+        }
+
         w.writeEndElement();
     }
 
-    const bool isCollection = tileset.isCollection();
     const bool includeAllTiles = isCollection || tileset.anyTileOutOfOrder();
 
     for (const Tile *tile : tileset.tiles()) {
diff --git a/src/libtiled/tileset.cpp b/src/libtiled/tileset.cpp
index ea27a7b9f8..0f2564b52e 100644
--- a/src/libtiled/tileset.cpp
+++ b/src/libtiled/tileset.cpp
@@ -228,31 +228,29 @@ bool Tileset::loadFromImage(const QString &fileName)
 }
 
 /**
- * Tries to load the image this tileset is referring to.
+ * Tries to load the image this tileset is referring to, if any.
  *
  * @return <code>true</code> if loading was successful, otherwise
  *         returns <code>false</code>
  */
 bool Tileset::loadImage()
 {
-    if (mTileWidth <= 0 || mTileHeight <= 0) {
-        mImageReference.status = LoadingError;
-        return false;
-    }
-
-    mImage = ImageCache::loadPixmap(Tiled::urlToLocalFileOrQrc(mImageReference.source));
-    if (mImage.isNull()) {
-        mImageReference.status = LoadingError;
-        return false;
+    if (mImageReference.hasImage()) {
+        mImage = mImageReference.create();
+        if (mImage.isNull()) {
+            mImageReference.status = LoadingError;
+            return false;
+        }
     }
 
-    initializeTilesetTiles();
-
-    return true;
+    return initializeTilesetTiles();
 }
 
-void Tileset::initializeTilesetTiles()
+bool Tileset::initializeTilesetTiles()
 {
+    if (mImage.isNull() || mTileWidth <= 0 || mTileHeight <= 0)
+        return false;
+
     if (mImageReference.transparentColor.isValid())
         mImage.setMask(mImage.createMaskFromColor(mImageReference.transparentColor));
 
@@ -294,6 +292,7 @@ void Tileset::initializeTilesetTiles()
     mImageReference.size = mImage.size();
     mColumnCount = columnCountForWidth(mImageReference.size.width());
     mImageReference.status = LoadingReady;
+    return true;
 }
 
 /**
diff --git a/src/libtiled/tileset.h b/src/libtiled/tileset.h
index d00602a4c6..c7b5b01156 100644
--- a/src/libtiled/tileset.h
+++ b/src/libtiled/tileset.h
@@ -198,6 +198,7 @@ class TILEDSHARED_EXPORT Tileset : public Object, public QEnableSharedFromThis<T
     bool loadFromImage(const QImage &image, const QString &source);
     bool loadFromImage(const QString &fileName);
     bool loadImage();
+    bool initializeTilesetTiles();
 
     SharedTileset findSimilarTileset(const QVector<SharedTileset> &tilesets) const;
 
@@ -293,8 +294,6 @@ class TILEDSHARED_EXPORT Tileset : public Object, public QEnableSharedFromThis<T
     static FillMode fillModeFromString(const QString &);
 
 private:
-    void initializeTilesetTiles();
-
     void maybeUpdateTileSize(QSize oldSize, QSize newSize);
     void updateTileSize();
 
@@ -642,11 +641,12 @@ inline const QPixmap &Tileset::image() const
 
 /**
  * Returns whether this tileset is a collection of images. In this case, the
- * tileset itself has no image source.
+ * tileset itself has no image source and the tileset image is also not
+ * embedded.
  */
 inline bool Tileset::isCollection() const
 {
-    return imageSource().isEmpty();
+    return imageSource().isEmpty() && image().isNull();
 }
 
 inline const QList<WangSet*> &Tileset::wangSets() const
diff --git a/src/libtiled/tilesetmanager.cpp b/src/libtiled/tilesetmanager.cpp
index 11f3a578f9..fa97cdcef3 100644
--- a/src/libtiled/tilesetmanager.cpp
+++ b/src/libtiled/tilesetmanager.cpp
@@ -151,7 +151,7 @@ void TilesetManager::reloadImages(Tileset *tileset)
             }
         }
         emit tilesetImagesChanged(tileset);
-    } else {
+    } else if (tileset->imageSource().isLocalFile()) {
         ImageCache::remove(tileset->imageSource().toLocalFile());
         if (tileset->loadImage())
             emit tilesetImagesChanged(tileset);
diff --git a/src/libtiled/varianttomapconverter.cpp b/src/libtiled/varianttomapconverter.cpp
index 1ed449a227..2c2b9bf3b5 100644
--- a/src/libtiled/varianttomapconverter.cpp
+++ b/src/libtiled/varianttomapconverter.cpp
@@ -125,9 +125,8 @@ std::unique_ptr<Map> VariantToMapConverter::toMap(const QVariant &variant,
     }
 
     // Try to load the tileset images
-    auto tilesets = map->tilesets();
-    for (SharedTileset &tileset : tilesets) {
-        if (!tileset->imageSource().isEmpty() && tileset->fileName().isEmpty())
+    for (const SharedTileset &tileset : map->tilesets()) {
+        if (tileset->fileName().isEmpty())
             tileset->loadImage();
     }
 
@@ -145,7 +144,7 @@ SharedTileset VariantToMapConverter::toTileset(const QVariant &variant,
     mReadingExternalTileset = true;
 
     SharedTileset tileset = toTileset(variant);
-    if (tileset && !tileset->imageSource().isEmpty())
+    if (tileset)
         tileset->loadImage();
 
     mReadingExternalTileset = false;
diff --git a/src/tiled/editabletileset.cpp b/src/tiled/editabletileset.cpp
index 4d6c4628f1..f5d05b1d9a 100644
--- a/src/tiled/editabletileset.cpp
+++ b/src/tiled/editabletileset.cpp
@@ -248,9 +248,7 @@ void EditableTileset::setImage(const QString &imageFilePath)
         push(new ChangeTilesetParameters(doc, parameters));
     } else if (!checkReadOnly()) {
         tileset()->setImageSource(imageFilePath);
-
-        if (!tileSize().isEmpty() && !image().isEmpty())
-            tileset()->loadImage();
+        tileset()->loadImage();
     }
 }
 
@@ -268,9 +266,43 @@ void EditableTileset::setTileSize(QSize size)
         push(new ChangeTilesetParameters(doc, parameters));
     } else if (!checkReadOnly()) {
         tileset()->setTileSize(size);
+        tileset()->initializeTilesetTiles();
+    }
+}
+
+void EditableTileset::setTileSpacing(int tileSpacing)
+{
+    if (isCollection() && tileCount() > 0) {
+        ScriptManager::instance().throwError(QCoreApplication::translate("Script Errors", "Can't set tile spacing on an image collection tileset"));
+        return;
+    }
+
+    if (auto doc = tilesetDocument()) {
+        TilesetParameters parameters(*tileset());
+        parameters.tileSpacing = tileSpacing;
 
-        if (!tileSize().isEmpty() && !image().isEmpty())
-            tileset()->loadImage();
+        push(new ChangeTilesetParameters(doc, parameters));
+    } else if (!checkReadOnly()) {
+        tileset()->setTileSpacing(tileSpacing);
+        tileset()->initializeTilesetTiles();
+    }
+}
+
+void EditableTileset::setMargin(int margin)
+{
+    if (isCollection() && tileCount() > 0) {
+        ScriptManager::instance().throwError(QCoreApplication::translate("Script Errors", "Can't set margin on an image collection tileset"));
+        return;
+    }
+
+    if (auto doc = tilesetDocument()) {
+        TilesetParameters parameters(*tileset());
+        parameters.margin = margin;
+
+        push(new ChangeTilesetParameters(doc, parameters));
+    } else if (!checkReadOnly()) {
+        tileset()->setMargin(margin);
+        tileset()->initializeTilesetTiles();
     }
 }
 
@@ -336,9 +368,7 @@ void EditableTileset::setTransparentColor(const QColor &color)
         push(new ChangeTilesetParameters(doc, parameters));
     } else if (!checkReadOnly()) {
         tileset()->setTransparentColor(color);
-
-        if (!tileSize().isEmpty() && !image().isEmpty())
-            tileset()->loadImage();
+        tileset()->initializeTilesetTiles();
     }
 }
 
diff --git a/src/tiled/editabletileset.h b/src/tiled/editabletileset.h
index b82112cf76..8db0a30fe8 100644
--- a/src/tiled/editabletileset.h
+++ b/src/tiled/editabletileset.h
@@ -47,8 +47,8 @@ class EditableTileset : public EditableAsset
     Q_PROPERTY(int imageWidth READ imageWidth)
     Q_PROPERTY(int imageHeight READ imageHeight)
     Q_PROPERTY(QSize imageSize READ imageSize)
-    Q_PROPERTY(int tileSpacing READ tileSpacing)
-    Q_PROPERTY(int margin READ margin)
+    Q_PROPERTY(int tileSpacing READ tileSpacing WRITE setTileSpacing)
+    Q_PROPERTY(int margin READ margin WRITE setMargin)
     Q_PROPERTY(Alignment objectAlignment READ objectAlignment WRITE setObjectAlignment)
     Q_PROPERTY(TileRenderSize tileRenderSize READ tileRenderSize WRITE setTileRenderSize)
     Q_PROPERTY(FillMode fillMode READ fillMode WRITE setFillMode)
@@ -157,6 +157,8 @@ public slots:
     void setTileHeight(int height);
     void setTileSize(QSize size);
     void setTileSize(int width, int height);
+    void setTileSpacing(int tileSpacing);
+    void setMargin(int margin);
     void setColumnCount(int columnCount);
     void setObjectAlignment(Alignment objectAlignment);
     void setTileRenderSize(TileRenderSize tileRenderSize);