diff --git a/src/main/java/io/bioimage/modelrunner/tensor/shm/SharedMemoryArrayLinux.java b/src/main/java/io/bioimage/modelrunner/tensor/shm/SharedMemoryArrayLinux.java
index 1c1ae2d5..a902618b 100644
--- a/src/main/java/io/bioimage/modelrunner/tensor/shm/SharedMemoryArrayLinux.java
+++ b/src/main/java/io/bioimage/modelrunner/tensor/shm/SharedMemoryArrayLinux.java
@@ -258,6 +258,14 @@ private SharedMemoryArrayLinux(String name, int size, String dtype, long[] shape
         	INSTANCE_C.close(shmFd);
             throw new RuntimeException("mmap failed, errno: " + Native.getLastError());
         }
+        
+        if (!alreadyExists && this.isNumpyFormat) {
+        	byte[] header = getNpyHeader(dtype, shape, this.isFortran);
+        	long offset = 0;
+        	for (byte b : header) {
+    			this.pSharedMemory.setByte(offset ++, b);
+        	}
+        }
     }
     
     /**
@@ -670,6 +678,35 @@ byte[] getNpyHeader(RandomAccessibleInterval<T> tensor, boolean fortranOrder) {
         return total;
     }
     
+    @SuppressWarnings("unchecked")
+	private static <T extends RealType<T> & NativeType<T>>
+    byte[] getNpyHeader(String dtype, long[] shape, boolean fortranOrder) {
+    	String strHeader = "{'descr': '<";
+    	strHeader += DecodeNumpy.getDataType((T) CommonUtils.getImgLib2DataType(dtype));
+    	strHeader += "', 'fortran_order': " + (fortranOrder ? "True" : "False") + ", 'shape': (";
+    	for (long ll : shape) strHeader += ll + ", ";
+    	strHeader = strHeader.substring(0, strHeader.length() - 2);
+    	strHeader += "), }" + System.lineSeparator();
+    	byte[] bufInverse = strHeader.getBytes(StandardCharsets.UTF_8);
+    	byte[] major = {1};
+        byte[] minor = {0};
+        byte[] len = new byte[2];
+        len[0] = (byte) (short) strHeader.length();
+        len[1] = (byte) (((short) strHeader.length()) >> 8);
+        int totalLen = DecodeNumpy.NUMPY_PREFIX.length + 2 + 2 + bufInverse.length;
+        byte[] total = new byte[totalLen];
+        int c = 0;
+        for (int i = 0; i < DecodeNumpy.NUMPY_PREFIX.length; i ++)
+        	total[c ++] = DecodeNumpy.NUMPY_PREFIX[i];
+        total[c ++] = major[0];
+        total[c ++] = minor[0];
+        total[c ++] = len[0];
+        total[c ++] = len[1];
+        for (int i = 0; i < bufInverse.length; i ++)
+        	total[c ++] = bufInverse[i];
+        return total;
+    }
+    
     /**
      * {@inheritDoc}
      */
diff --git a/src/main/java/io/bioimage/modelrunner/tensor/shm/SharedMemoryArrayMacOS.java b/src/main/java/io/bioimage/modelrunner/tensor/shm/SharedMemoryArrayMacOS.java
index 3a0cfac8..52739338 100644
--- a/src/main/java/io/bioimage/modelrunner/tensor/shm/SharedMemoryArrayMacOS.java
+++ b/src/main/java/io/bioimage/modelrunner/tensor/shm/SharedMemoryArrayMacOS.java
@@ -243,6 +243,16 @@ protected SharedMemoryArrayMacOS(String name, int size, String dtype, long[] sha
         	INSTANCE.close(shmFd);
             throw new RuntimeException("mmap failed, errno: " + Native.getLastError());
         }
+        
+
+        
+        if (!alreadyExists && this.isNumpyFormat) {
+        	byte[] header = getNpyHeader(dtype, shape, this.isFortran);
+        	long offset = 0;
+        	for (byte b : header) {
+    			this.pSharedMemory.setByte(offset ++, b);
+        	}
+        }
     }
     
     /**
@@ -597,6 +607,35 @@ private void buildFloat64(RandomAccessibleInterval<DoubleType> tensor, boolean i
 		}
     }
     
+    @SuppressWarnings("unchecked")
+	private static <T extends RealType<T> & NativeType<T>>
+    byte[] getNpyHeader(String dtype, long[] shape, boolean fortranOrder) {
+    	String strHeader = "{'descr': '<";
+    	strHeader += DecodeNumpy.getDataType((T) CommonUtils.getImgLib2DataType(dtype));
+    	strHeader += "', 'fortran_order': " + (fortranOrder ? "True" : "False") + ", 'shape': (";
+    	for (long ll : shape) strHeader += ll + ", ";
+    	strHeader = strHeader.substring(0, strHeader.length() - 2);
+    	strHeader += "), }" + System.lineSeparator();
+    	byte[] bufInverse = strHeader.getBytes(StandardCharsets.UTF_8);
+    	byte[] major = {1};
+        byte[] minor = {0};
+        byte[] len = new byte[2];
+        len[0] = (byte) (short) strHeader.length();
+        len[1] = (byte) (((short) strHeader.length()) >> 8);
+        int totalLen = DecodeNumpy.NUMPY_PREFIX.length + 2 + 2 + bufInverse.length;
+        byte[] total = new byte[totalLen];
+        int c = 0;
+        for (int i = 0; i < DecodeNumpy.NUMPY_PREFIX.length; i ++)
+        	total[c ++] = DecodeNumpy.NUMPY_PREFIX[i];
+        total[c ++] = major[0];
+        total[c ++] = minor[0];
+        total[c ++] = len[0];
+        total[c ++] = len[1];
+        for (int i = 0; i < bufInverse.length; i ++)
+        	total[c ++] = bufInverse[i];
+        return total;
+    }
+    
     private static <T extends RealType<T> & NativeType<T>>
     byte[] getNpyHeader(RandomAccessibleInterval<T> tensor, boolean isFortran) {
     	String strHeader = "{'descr': '<";
diff --git a/src/main/java/io/bioimage/modelrunner/tensor/shm/SharedMemoryArrayWin.java b/src/main/java/io/bioimage/modelrunner/tensor/shm/SharedMemoryArrayWin.java
index d42ada1c..b8f0cae4 100644
--- a/src/main/java/io/bioimage/modelrunner/tensor/shm/SharedMemoryArrayWin.java
+++ b/src/main/java/io/bioimage/modelrunner/tensor/shm/SharedMemoryArrayWin.java
@@ -218,7 +218,8 @@ protected SharedMemoryArrayWin(String name, int size, String dtype, long[] shape
     	this.isFortran = isFortran;
     	int flag = WinNT.PAGE_READWRITE;
     	boolean write = true;
-    	if (checkSHMExists(memoryName)) {
+    	boolean alreadyExists = checkSHMExists(memoryName);
+    	if (alreadyExists) {
         	long prevSize = getSHMSize(name);
         	if (prevSize != 0 && prevSize != DEFAULT_RESERVED_MEMORY && prevSize < size)
         		throw new FileAlreadyExistsException("Shared memory segment already exists with different dimensions, data type or format. "
@@ -271,6 +272,16 @@ protected SharedMemoryArrayWin(String name, int size, String dtype, long[] shape
                 		+ "" + Kernel32.INSTANCE.GetLastError());
     	    }
         }
+        
+
+        
+        if (!alreadyExists && this.isNumpyFormat) {
+        	byte[] header = getNpyHeader(dtype, shape, this.isFortran);
+        	long offset = 0;
+        	for (byte b : header) {
+    			this.mappedPointer.setByte(offset, b);
+        	}
+        }
     }
 	
 	private boolean checkSHMExists(String memoryName) {
@@ -486,6 +497,35 @@ private void addByteArray(byte[] arr) {
     	}
     }
     
+    @SuppressWarnings("unchecked")
+	private static <T extends RealType<T> & NativeType<T>>
+    byte[] getNpyHeader(String dtype, long[] shape, boolean fortranOrder) {
+    	String strHeader = "{'descr': '<";
+    	strHeader += DecodeNumpy.getDataType((T) CommonUtils.getImgLib2DataType(dtype));
+    	strHeader += "', 'fortran_order': " + (fortranOrder ? "True" : "False") + ", 'shape': (";
+    	for (long ll : shape) strHeader += ll + ", ";
+    	strHeader = strHeader.substring(0, strHeader.length() - 2);
+    	strHeader += "), }" + System.lineSeparator();
+    	byte[] bufInverse = strHeader.getBytes(StandardCharsets.UTF_8);
+    	byte[] major = {1};
+        byte[] minor = {0};
+        byte[] len = new byte[2];
+        len[0] = (byte) (short) strHeader.length();
+        len[1] = (byte) (((short) strHeader.length()) >> 8);
+        int totalLen = DecodeNumpy.NUMPY_PREFIX.length + 2 + 2 + bufInverse.length;
+        byte[] total = new byte[totalLen];
+        int c = 0;
+        for (int i = 0; i < DecodeNumpy.NUMPY_PREFIX.length; i ++)
+        	total[c ++] = DecodeNumpy.NUMPY_PREFIX[i];
+        total[c ++] = major[0];
+        total[c ++] = minor[0];
+        total[c ++] = len[0];
+        total[c ++] = len[1];
+        for (int i = 0; i < bufInverse.length; i ++)
+        	total[c ++] = bufInverse[i];
+        return total;
+    }
+    
     private static <T extends RealType<T> & NativeType<T>>
     byte[] getNpyHeader(RandomAccessibleInterval<T> tensor, boolean isFortran) {
     	String strHeader = "{'descr': '<";