diff --git a/doc/using.md b/doc/using.md
index 87930e33..69c3336b 100644
--- a/doc/using.md
+++ b/doc/using.md
@@ -291,6 +291,29 @@ FluxEngine also supports a number of file system image formats. When using the
   circumstances as it can represent arbitrary sector layouts as read
   from the floppy.
   
+  - `<filename.imd>`
+
+  Read from a [imd image file](http://dunfield.classiccmp.org/img/index.htm),
+  imd images are entire diskette images read into a file (type .IMD),
+  it's purpose is to recreate a copy of the diskette from that image. A detailed analysis
+  is performed on the diskette, and information about the formatting is recorded
+  in the image file. This allows ImageDisk to work with virtually any soft-
+  sectored diskette format that is compatible with the PC's type 765 floppy
+  diskette controller and drives.
+  
+  FluxEngine is able to read from and write to an imd image file.
+  
+  The imd reader should mostly be used with the `ibm` profile or ibm deratives 
+  and will override most encoding parameters on a track-by-track basis.
+  
+  The imd writer should likewise mostly be used with the `ibm` profile in most
+  circumstances as it can represent arbitrary sector layouts as read
+  from the floppy.
+
+  With options it is possible to add a comment for the resulting image when archiving
+  floppies. By default imd images assume MFM encoding, but this can by changed
+  by suppling the option RECMODE_FM. 
+
   - `<filename.nfd>`
 
   Read from a [NFD r0 image file](https://www.pc98.org/project/doc/nfdr0.html),
diff --git a/lib/imagewriter/imdimagewriter.cc b/lib/imagewriter/imdimagewriter.cc
index 41e0cbcd..492c7e05 100644
--- a/lib/imagewriter/imdimagewriter.cc
+++ b/lib/imagewriter/imdimagewriter.cc
@@ -135,23 +135,19 @@ public:
 	void writeImage(const Image& image)
 	{
  		const Geometry& geometry = image.getGeometry();
-		unsigned numCylinders;
 		unsigned numHeads;
 		unsigned numSectors;
 		unsigned numBytes;
 		std::ofstream outputFile(_config.filename(), std::ios::out | std::ios::binary);
 		if (!outputFile.is_open())
 			Error() << "IMD: cannot open output file";
-		uint32_t offset = 0;
+//		uint32_t offset = 0;
 		unsigned numSectorsinTrack = 0;
 
 		numHeads = geometry.numSides;
 		numSectors = geometry.numSectors;
 		numBytes = geometry.sectorSize;
 
-		size_t headSize = geometry.numSectors * geometry.sectorSize;
-		size_t trackSize = headSize * geometry.numSides;
-		
 		Bytes imagenew;
 		ByteWriter bw(imagenew);
 
@@ -421,10 +417,9 @@ public:
 				}
 			}
 		}
-		numCylinders = geometry.numTracks; //-emptyCylinders; //calculate the cylinders with sectors and hence data. Otherwise the calculation of kB goes wrong
 		imagenew.writeTo(outputFile);
 		Logger() << fmt::format("IMD: Written {} tracks, {} heads, {} sectors, {} bytes per sector, {} kB total",
-				numCylinders, numHeads,
+				geometry.numTracks, numHeads,
 				numSectors, numBytes,
 				outputFile.tellp() / 1024);
  	}