diff --git a/ArcFormats/Interheart/ImageKG.cs b/ArcFormats/Interheart/ImageKG.cs
index 43677246..4a95ed52 100644
--- a/ArcFormats/Interheart/ImageKG.cs
+++ b/ArcFormats/Interheart/ImageKG.cs
@@ -26,7 +26,11 @@
 using System;
 using System.ComponentModel.Composition;
 using System.IO;
+using System.Linq;
+using System.Collections.Generic;
+using System.Windows;
 using System.Windows.Media;
+using System.Windows.Media.Imaging;
 using GameRes.Utility;
 
 namespace GameRes.Formats.Interheart
@@ -37,6 +41,7 @@ namespace GameRes.Formats.Interheart
         public override string         Tag { get { return "KG"; } }
         public override string Description { get { return "Interheart image format"; } }
         public override uint     Signature { get { return 0x4B474347; } } // 'GCGK'
+        public override bool      CanWrite { get { return true; } }
 
         public override ImageMetaData ReadMetaData (IBinaryStream stream)
         {
@@ -94,9 +99,78 @@ namespace GameRes.Formats.Interheart
             return ImageData.Create (info, PixelFormats.Bgra32, null, pixels);
         }
 
-        public override void Write (Stream file, ImageData image)
-        {
-            throw new System.NotImplementedException ("KgFormat.Write not implemented");
+        public override void Write (Stream file, ImageData image) {
+          int stride = (int)image.Width * 4;
+          byte[] bitmap = new byte[stride * image.Height];
+          {
+            var image_bgra = image.Bitmap.Format != PixelFormats.Bgra32
+              ? new FormatConvertedBitmap(image.Bitmap, PixelFormats.Bgra32, null, 0)
+              : image.Bitmap;
+            image_bgra.CopyPixels(bitmap, stride, 0);
+          }
+          uint[] offset_table = new uint[image.Height];
+          var kg_data = new List<byte>();
+
+          for (int y = 0; y < image.Height; y++) {
+            offset_table[y] = (uint)kg_data.Count();
+
+            bitmap
+              .AsMemory()
+              .Slice(y * stride, stride)
+              .Chunk(4)
+              .Aggregate(new List<(byte alpha, List<byte[]> data)> {  }, (chunks, x) => {
+                var pixel = x.ToArray();
+                void new_chunk () => chunks.Add((alpha: pixel[3], data: new List<byte[]> { pixel }));
+
+                if (!chunks.Any()) {
+                  new_chunk();
+                }
+                else {
+                  var (alpha, data) = chunks.Last();
+                  if (pixel[3] != data.Last()[3] || data.Count >= 256) {
+                    new_chunk();
+                  }
+                  else {
+                    data.Add(pixel);
+                  }
+                }
+                return chunks;
+              }
+            )
+            .ForEach(chunk => {
+              kg_data.Add(chunk.alpha);
+              kg_data.Add((byte)chunk.data.Count());
+              if (chunk.alpha > 0) {
+                kg_data.AddRange(chunk.data.SelectMany(p => new[] { p[2], p[1], p[0] }));
+              }
+            });
+          }
+
+
+          var bw = new BinaryWriter(file);
+
+          bw.Write(new byte[] { 0x47, 0x43, 0x47, 0x4B });
+          bw.Write((UInt16)image.Width);
+          bw.Write((UInt16)image.Height);
+          bw.Write((uint)kg_data.Count);
+
+          {
+            byte[] buf = new byte[offset_table.Length * sizeof(uint)];
+            Buffer.BlockCopy(offset_table, 0, buf, 0, buf.Length);
+            bw.Write(buf);
+          }
+
+          bw.Write(kg_data.ToArray());
+        }
+      }
+
+      static class Extensions {
+        public static IEnumerable<Memory<T>> Chunk<T>(this Memory<T> arr, int size) {
+          for (var i = 0; i < arr.Length / size + 1; i++) {
+            if (i * size < arr.Length) {
+              yield return arr.Slice(i * size, size);
+            }
+          }
         }
     }
 }