diff --git a/pyext/GFitsImageByte.i b/pyext/GFitsImageByte.i
index 052be0e..d61f946 100644
--- a/pyext/GFitsImageByte.i
+++ b/pyext/GFitsImageByte.i
@@ -65,30 +65,55 @@ public:
  ***************************************************************************/
 %extend GFitsImageByte {
     unsigned char __getitem__(int GFitsImageInx[]) {
-        if (GFitsImageInx[0] == 1)
-            return self->at(GFitsImageInx[1]);
-        else if (GFitsImageInx[0] == 2)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2]);
-        else if (GFitsImageInx[0] == 3)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]);
-        else if (GFitsImageInx[0] == 4)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3], GFitsImageInx[4]);
-        else
+        // Check image dimensions
+        for (int i = 0; i < GFitsImageInx[0]; ++i) {
+             if (GFitsImageInx[i+1] < 0 || GFitsImageInx[i+1] >= self->naxes(i)) {
+                throw GException::out_of_range("__getitem__(int)",
+                                               "FITS image axis "+
+                                               gammalib::str(i)+" index",
+                                               GFitsImageInx[i+1],
+                                               self->naxes(i));
+            }
+        }
+        // Return pixel value
+        if (GFitsImageInx[0] == 1) {
+            return (*self)(GFitsImageInx[1]);
+        }
+        else if (GFitsImageInx[0] == 2) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2]);
+        }
+        else if (GFitsImageInx[0] == 3) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]);
+        }
+        else if (GFitsImageInx[0] == 4) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3],
+                           GFitsImageInx[4]);
+        }
+        else {
             throw GException::fits_wrong_image_operator("__getitem__(int)",
                                                         self->naxis(), GFitsImageInx[0]);
+        }
     }
     void __setitem__(int GFitsImageInx[], unsigned char value) {
-        if (GFitsImageInx[0] == 1)
+        if (GFitsImageInx[0] == 1) {
             self->at(GFitsImageInx[1]) = value;
-        else if (GFitsImageInx[0] == 2)
+        }
+        else if (GFitsImageInx[0] == 2) {
             self->at(GFitsImageInx[1], GFitsImageInx[2]) = value;
-        else if (GFitsImageInx[0] == 3)
-            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]) = value;
-        else if (GFitsImageInx[0] == 4)
-            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3], GFitsImageInx[4]) = value;
-        else
+        }
+        else if (GFitsImageInx[0] == 3) {
+            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]) =
+                     value;
+        }
+        else if (GFitsImageInx[0] == 4) {
+            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3],
+                     GFitsImageInx[4]) = value;
+        }
+        else {
             throw GException::fits_wrong_image_operator("__setitem__(int)",
-                                                        self->naxis(), GFitsImageInx[0]);
+                                                        self->naxis(),
+                                                        GFitsImageInx[0]);
+        }
     }
     GFitsImageByte copy() {
         return (*self);
diff --git a/pyext/GFitsImageDouble.i b/pyext/GFitsImageDouble.i
index ed8f142..e01bccc 100644
--- a/pyext/GFitsImageDouble.i
+++ b/pyext/GFitsImageDouble.i
@@ -65,30 +65,55 @@ public:
  ***************************************************************************/
 %extend GFitsImageDouble {
     double __getitem__(int GFitsImageInx[]) {
-        if (GFitsImageInx[0] == 1)
-            return self->at(GFitsImageInx[1]);
-        else if (GFitsImageInx[0] == 2)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2]);
-        else if (GFitsImageInx[0] == 3)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]);
-        else if (GFitsImageInx[0] == 4)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3], GFitsImageInx[4]);
-        else
+        // Check image dimensions
+        for (int i = 0; i < GFitsImageInx[0]; ++i) {
+             if (GFitsImageInx[i+1] < 0 || GFitsImageInx[i+1] >= self->naxes(i)) {
+                throw GException::out_of_range("__getitem__(int)",
+                                               "FITS image axis "+
+                                               gammalib::str(i)+" index",
+                                               GFitsImageInx[i+1],
+                                               self->naxes(i));
+            }
+        }
+        // Return pixel value
+        if (GFitsImageInx[0] == 1) {
+            return (*self)(GFitsImageInx[1]);
+        }
+        else if (GFitsImageInx[0] == 2) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2]);
+        }
+        else if (GFitsImageInx[0] == 3) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]);
+        }
+        else if (GFitsImageInx[0] == 4) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3],
+                           GFitsImageInx[4]);
+        }
+        else {
             throw GException::fits_wrong_image_operator("__getitem__(int)",
                                                         self->naxis(), GFitsImageInx[0]);
+        }
     }
     void __setitem__(int GFitsImageInx[], double value) {
-        if (GFitsImageInx[0] == 1)
+        if (GFitsImageInx[0] == 1) {
             self->at(GFitsImageInx[1]) = value;
-        else if (GFitsImageInx[0] == 2)
+        }
+        else if (GFitsImageInx[0] == 2) {
             self->at(GFitsImageInx[1], GFitsImageInx[2]) = value;
-        else if (GFitsImageInx[0] == 3)
-            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]) = value;
-        else if (GFitsImageInx[0] == 4)
-            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3], GFitsImageInx[4]) = value;
-        else
+        }
+        else if (GFitsImageInx[0] == 3) {
+            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]) =
+                     value;
+        }
+        else if (GFitsImageInx[0] == 4) {
+            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3],
+                     GFitsImageInx[4]) = value;
+        }
+        else {
             throw GException::fits_wrong_image_operator("__setitem__(int)",
-                                                        self->naxis(), GFitsImageInx[0]);
+                                                        self->naxis(),
+                                                        GFitsImageInx[0]);
+        }
     }
     GFitsImageDouble copy() {
         return (*self);
diff --git a/pyext/GFitsImageFloat.i b/pyext/GFitsImageFloat.i
index 64fe9f9..df932d0 100644
--- a/pyext/GFitsImageFloat.i
+++ b/pyext/GFitsImageFloat.i
@@ -65,30 +65,55 @@ public:
  ***************************************************************************/
 %extend GFitsImageFloat {
     float __getitem__(int GFitsImageInx[]) {
-        if (GFitsImageInx[0] == 1)
-            return self->at(GFitsImageInx[1]);
-        else if (GFitsImageInx[0] == 2)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2]);
-        else if (GFitsImageInx[0] == 3)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]);
-        else if (GFitsImageInx[0] == 4)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3], GFitsImageInx[4]);
-        else
+        // Check image dimensions
+        for (int i = 0; i < GFitsImageInx[0]; ++i) {
+             if (GFitsImageInx[i+1] < 0 || GFitsImageInx[i+1] >= self->naxes(i)) {
+                throw GException::out_of_range("__getitem__(int)",
+                                               "FITS image axis "+
+                                               gammalib::str(i)+" index",
+                                               GFitsImageInx[i+1],
+                                               self->naxes(i));
+            }
+        }
+        // Return pixel value
+        if (GFitsImageInx[0] == 1) {
+            return (*self)(GFitsImageInx[1]);
+        }
+        else if (GFitsImageInx[0] == 2) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2]);
+        }
+        else if (GFitsImageInx[0] == 3) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]);
+        }
+        else if (GFitsImageInx[0] == 4) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3],
+                           GFitsImageInx[4]);
+        }
+        else {
             throw GException::fits_wrong_image_operator("__getitem__(int)",
                                                         self->naxis(), GFitsImageInx[0]);
+        }
     }
     void __setitem__(int GFitsImageInx[], float value) {
-        if (GFitsImageInx[0] == 1)
+        if (GFitsImageInx[0] == 1) {
             self->at(GFitsImageInx[1]) = value;
-        else if (GFitsImageInx[0] == 2)
+        }
+        else if (GFitsImageInx[0] == 2) {
             self->at(GFitsImageInx[1], GFitsImageInx[2]) = value;
-        else if (GFitsImageInx[0] == 3)
-            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]) = value;
-        else if (GFitsImageInx[0] == 4)
-            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3], GFitsImageInx[4]) = value;
-        else
+        }
+        else if (GFitsImageInx[0] == 3) {
+            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]) =
+                     value;
+        }
+        else if (GFitsImageInx[0] == 4) {
+            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3],
+                     GFitsImageInx[4]) = value;
+        }
+        else {
             throw GException::fits_wrong_image_operator("__setitem__(int)",
-                                                        self->naxis(), GFitsImageInx[0]);
+                                                        self->naxis(),
+                                                        GFitsImageInx[0]);
+        }
     }
     GFitsImageFloat copy() {
         return (*self);
diff --git a/pyext/GFitsImageLong.i b/pyext/GFitsImageLong.i
index 3fdc134..334da8b 100644
--- a/pyext/GFitsImageLong.i
+++ b/pyext/GFitsImageLong.i
@@ -65,30 +65,55 @@ public:
  ***************************************************************************/
 %extend GFitsImageLong {
     long __getitem__(int GFitsImageInx[]) {
-        if (GFitsImageInx[0] == 1)
-            return self->at(GFitsImageInx[1]);
-        else if (GFitsImageInx[0] == 2)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2]);
-        else if (GFitsImageInx[0] == 3)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]);
-        else if (GFitsImageInx[0] == 4)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3], GFitsImageInx[4]);
-        else
+        // Check image dimensions
+        for (int i = 0; i < GFitsImageInx[0]; ++i) {
+             if (GFitsImageInx[i+1] < 0 || GFitsImageInx[i+1] >= self->naxes(i)) {
+                throw GException::out_of_range("__getitem__(int)",
+                                               "FITS image axis "+
+                                               gammalib::str(i)+" index",
+                                               GFitsImageInx[i+1],
+                                               self->naxes(i));
+            }
+        }
+        // Return pixel value
+        if (GFitsImageInx[0] == 1) {
+            return (*self)(GFitsImageInx[1]);
+        }
+        else if (GFitsImageInx[0] == 2) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2]);
+        }
+        else if (GFitsImageInx[0] == 3) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]);
+        }
+        else if (GFitsImageInx[0] == 4) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3],
+                           GFitsImageInx[4]);
+        }
+        else {
             throw GException::fits_wrong_image_operator("__getitem__(int)",
                                                         self->naxis(), GFitsImageInx[0]);
+        }
     }
     void __setitem__(int GFitsImageInx[], long value) {
-        if (GFitsImageInx[0] == 1)
+        if (GFitsImageInx[0] == 1) {
             self->at(GFitsImageInx[1]) = value;
-        else if (GFitsImageInx[0] == 2)
+        }
+        else if (GFitsImageInx[0] == 2) {
             self->at(GFitsImageInx[1], GFitsImageInx[2]) = value;
-        else if (GFitsImageInx[0] == 3)
-            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]) = value;
-        else if (GFitsImageInx[0] == 4)
-            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3], GFitsImageInx[4]) = value;
-        else
+        }
+        else if (GFitsImageInx[0] == 3) {
+            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]) =
+                     value;
+        }
+        else if (GFitsImageInx[0] == 4) {
+            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3],
+                     GFitsImageInx[4]) = value;
+        }
+        else {
             throw GException::fits_wrong_image_operator("__setitem__(int)",
-                                                        self->naxis(), GFitsImageInx[0]);
+                                                        self->naxis(),
+                                                        GFitsImageInx[0]);
+        }
     }
     GFitsImageLong copy() {
         return (*self);
diff --git a/pyext/GFitsImageLongLong.i b/pyext/GFitsImageLongLong.i
index 88e1016..79ae6e8 100644
--- a/pyext/GFitsImageLongLong.i
+++ b/pyext/GFitsImageLongLong.i
@@ -65,30 +65,55 @@ public:
  ***************************************************************************/
 %extend GFitsImageLongLong {
     long long __getitem__(int GFitsImageInx[]) {
-        if (GFitsImageInx[0] == 1)
-            return self->at(GFitsImageInx[1]);
-        else if (GFitsImageInx[0] == 2)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2]);
-        else if (GFitsImageInx[0] == 3)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]);
-        else if (GFitsImageInx[0] == 4)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3], GFitsImageInx[4]);
-        else
+        // Check image dimensions
+        for (int i = 0; i < GFitsImageInx[0]; ++i) {
+             if (GFitsImageInx[i+1] < 0 || GFitsImageInx[i+1] >= self->naxes(i)) {
+                throw GException::out_of_range("__getitem__(int)",
+                                               "FITS image axis "+
+                                               gammalib::str(i)+" index",
+                                               GFitsImageInx[i+1],
+                                               self->naxes(i));
+            }
+        }
+        // Return pixel value
+        if (GFitsImageInx[0] == 1) {
+            return (*self)(GFitsImageInx[1]);
+        }
+        else if (GFitsImageInx[0] == 2) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2]);
+        }
+        else if (GFitsImageInx[0] == 3) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]);
+        }
+        else if (GFitsImageInx[0] == 4) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3],
+                           GFitsImageInx[4]);
+        }
+        else {
             throw GException::fits_wrong_image_operator("__getitem__(int)",
                                                         self->naxis(), GFitsImageInx[0]);
+        }
     }
     void __setitem__(int GFitsImageInx[], long long value) {
-        if (GFitsImageInx[0] == 1)
+        if (GFitsImageInx[0] == 1) {
             self->at(GFitsImageInx[1]) = value;
-        else if (GFitsImageInx[0] == 2)
+        }
+        else if (GFitsImageInx[0] == 2) {
             self->at(GFitsImageInx[1], GFitsImageInx[2]) = value;
-        else if (GFitsImageInx[0] == 3)
-            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]) = value;
-        else if (GFitsImageInx[0] == 4)
-            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3], GFitsImageInx[4]) = value;
-        else
+        }
+        else if (GFitsImageInx[0] == 3) {
+            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]) =
+                     value;
+        }
+        else if (GFitsImageInx[0] == 4) {
+            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3],
+                     GFitsImageInx[4]) = value;
+        }
+        else {
             throw GException::fits_wrong_image_operator("__setitem__(int)",
-                                                        self->naxis(), GFitsImageInx[0]);
+                                                        self->naxis(),
+                                                        GFitsImageInx[0]);
+        }
     }
     GFitsImageLongLong copy() {
         return (*self);
diff --git a/pyext/GFitsImageSByte.i b/pyext/GFitsImageSByte.i
index 4157f14..d43004f 100644
--- a/pyext/GFitsImageSByte.i
+++ b/pyext/GFitsImageSByte.i
@@ -65,30 +65,55 @@ public:
  ***************************************************************************/
 %extend GFitsImageSByte {
     char __getitem__(int GFitsImageInx[]) {
-        if (GFitsImageInx[0] == 1)
-            return self->at(GFitsImageInx[1]);
-        else if (GFitsImageInx[0] == 2)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2]);
-        else if (GFitsImageInx[0] == 3)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]);
-        else if (GFitsImageInx[0] == 4)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3], GFitsImageInx[4]);
-        else
+        // Check image dimensions
+        for (int i = 0; i < GFitsImageInx[0]; ++i) {
+             if (GFitsImageInx[i+1] < 0 || GFitsImageInx[i+1] >= self->naxes(i)) {
+                throw GException::out_of_range("__getitem__(int)",
+                                               "FITS image axis "+
+                                               gammalib::str(i)+" index",
+                                               GFitsImageInx[i+1],
+                                               self->naxes(i));
+            }
+        }
+        // Return pixel value
+        if (GFitsImageInx[0] == 1) {
+            return (*self)(GFitsImageInx[1]);
+        }
+        else if (GFitsImageInx[0] == 2) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2]);
+        }
+        else if (GFitsImageInx[0] == 3) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]);
+        }
+        else if (GFitsImageInx[0] == 4) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3],
+                           GFitsImageInx[4]);
+        }
+        else {
             throw GException::fits_wrong_image_operator("__getitem__(int)",
                                                         self->naxis(), GFitsImageInx[0]);
+        }
     }
     void __setitem__(int GFitsImageInx[], char value) {
-        if (GFitsImageInx[0] == 1)
+        if (GFitsImageInx[0] == 1) {
             self->at(GFitsImageInx[1]) = value;
-        else if (GFitsImageInx[0] == 2)
+        }
+        else if (GFitsImageInx[0] == 2) {
             self->at(GFitsImageInx[1], GFitsImageInx[2]) = value;
-        else if (GFitsImageInx[0] == 3)
-            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]) = value;
-        else if (GFitsImageInx[0] == 4)
-            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3], GFitsImageInx[4]) = value;
-        else
+        }
+        else if (GFitsImageInx[0] == 3) {
+            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]) =
+                     value;
+        }
+        else if (GFitsImageInx[0] == 4) {
+            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3],
+                     GFitsImageInx[4]) = value;
+        }
+        else {
             throw GException::fits_wrong_image_operator("__setitem__(int)",
-                                                        self->naxis(), GFitsImageInx[0]);
+                                                        self->naxis(),
+                                                        GFitsImageInx[0]);
+        }
     }
     GFitsImageSByte copy() {
         return (*self);
diff --git a/pyext/GFitsImageShort.i b/pyext/GFitsImageShort.i
index 89f19c5..169d9cc 100644
--- a/pyext/GFitsImageShort.i
+++ b/pyext/GFitsImageShort.i
@@ -66,29 +66,55 @@ public:
 %extend GFitsImageShort {
     short __getitem__(int GFitsImageInx[]) {
         if (GFitsImageInx[0] == 1)
-            return self->at(GFitsImageInx[1]);
-        else if (GFitsImageInx[0] == 2)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2]);
-        else if (GFitsImageInx[0] == 3)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]);
-        else if (GFitsImageInx[0] == 4)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3], GFitsImageInx[4]);
-        else
+        // Check image dimensions
+        for (int i = 0; i < GFitsImageInx[0]; ++i) {
+             if (GFitsImageInx[i+1] < 0 || GFitsImageInx[i+1] >= self->naxes(i)) {
+                throw GException::out_of_range("__getitem__(int)",
+                                               "FITS image axis "+
+                                               gammalib::str(i)+" index",
+                                               GFitsImageInx[i+1],
+                                               self->naxes(i));
+            }
+        }
+        // Return pixel value
+        if (GFitsImageInx[0] == 1) {
+            return (*self)(GFitsImageInx[1]);
+        }
+        else if (GFitsImageInx[0] == 2) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2]);
+        }
+        else if (GFitsImageInx[0] == 3) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]);
+        }
+        else if (GFitsImageInx[0] == 4) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3],
+                           GFitsImageInx[4]);
+        }
+        else {
             throw GException::fits_wrong_image_operator("__getitem__(int)",
                                                         self->naxis(), GFitsImageInx[0]);
+        }
     }
     void __setitem__(int GFitsImageInx[], short value) {
-        if (GFitsImageInx[0] == 1)
+        if (GFitsImageInx[0] == 1) {
             self->at(GFitsImageInx[1]) = value;
-        else if (GFitsImageInx[0] == 2)
+        }
+        else if (GFitsImageInx[0] == 2) {
             self->at(GFitsImageInx[1], GFitsImageInx[2]) = value;
-        else if (GFitsImageInx[0] == 3)
-            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]) = value;
-        else if (GFitsImageInx[0] == 4)
-            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3], GFitsImageInx[4]) = value;
-        else
+        }
+        else if (GFitsImageInx[0] == 3) {
+            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]) =
+                     value;
+        }
+        else if (GFitsImageInx[0] == 4) {
+            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3],
+                     GFitsImageInx[4]) = value;
+        }
+        else {
             throw GException::fits_wrong_image_operator("__setitem__(int)",
-                                                        self->naxis(), GFitsImageInx[0]);
+                                                        self->naxis(),
+                                                        GFitsImageInx[0]);
+        }
     }
     GFitsImageShort copy() {
         return (*self);
diff --git a/pyext/GFitsImageULong.i b/pyext/GFitsImageULong.i
index ae384f1..6d55cc5 100644
--- a/pyext/GFitsImageULong.i
+++ b/pyext/GFitsImageULong.i
@@ -65,30 +65,55 @@ public:
  ***************************************************************************/
 %extend GFitsImageULong {
     unsigned long __getitem__(int GFitsImageInx[]) {
-        if (GFitsImageInx[0] == 1)
-            return self->at(GFitsImageInx[1]);
-        else if (GFitsImageInx[0] == 2)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2]);
-        else if (GFitsImageInx[0] == 3)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]);
-        else if (GFitsImageInx[0] == 4)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3], GFitsImageInx[4]);
-        else
+        // Check image dimensions
+        for (int i = 0; i < GFitsImageInx[0]; ++i) {
+             if (GFitsImageInx[i+1] < 0 || GFitsImageInx[i+1] >= self->naxes(i)) {
+                throw GException::out_of_range("__getitem__(int)",
+                                               "FITS image axis "+
+                                               gammalib::str(i)+" index",
+                                               GFitsImageInx[i+1],
+                                               self->naxes(i));
+            }
+        }
+        // Return pixel value
+        if (GFitsImageInx[0] == 1) {
+            return (*self)(GFitsImageInx[1]);
+        }
+        else if (GFitsImageInx[0] == 2) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2]);
+        }
+        else if (GFitsImageInx[0] == 3) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]);
+        }
+        else if (GFitsImageInx[0] == 4) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3],
+                           GFitsImageInx[4]);
+        }
+        else {
             throw GException::fits_wrong_image_operator("__getitem__(int)",
                                                         self->naxis(), GFitsImageInx[0]);
+        }
     }
     void __setitem__(int GFitsImageInx[], unsigned long value) {
-        if (GFitsImageInx[0] == 1)
+        if (GFitsImageInx[0] == 1) {
             self->at(GFitsImageInx[1]) = value;
-        else if (GFitsImageInx[0] == 2)
+        }
+        else if (GFitsImageInx[0] == 2) {
             self->at(GFitsImageInx[1], GFitsImageInx[2]) = value;
-        else if (GFitsImageInx[0] == 3)
-            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]) = value;
-        else if (GFitsImageInx[0] == 4)
-            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3], GFitsImageInx[4]) = value;
-        else
+        }
+        else if (GFitsImageInx[0] == 3) {
+            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]) =
+                     value;
+        }
+        else if (GFitsImageInx[0] == 4) {
+            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3],
+                     GFitsImageInx[4]) = value;
+        }
+        else {
             throw GException::fits_wrong_image_operator("__setitem__(int)",
-                                                        self->naxis(), GFitsImageInx[0]);
+                                                        self->naxis(),
+                                                        GFitsImageInx[0]);
+        }
     }
     GFitsImageULong copy() {
         return (*self);
diff --git a/pyext/GFitsImageUShort.i b/pyext/GFitsImageUShort.i
index 85c1abf..36f0027 100644
--- a/pyext/GFitsImageUShort.i
+++ b/pyext/GFitsImageUShort.i
@@ -66,30 +66,55 @@ public:
  ***************************************************************************/
 %extend GFitsImageUShort {
     unsigned short __getitem__(int GFitsImageInx[]) {
-        if (GFitsImageInx[0] == 1)
-            return self->at(GFitsImageInx[1]);
-        else if (GFitsImageInx[0] == 2)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2]);
-        else if (GFitsImageInx[0] == 3)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]);
-        else if (GFitsImageInx[0] == 4)
-            return self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3], GFitsImageInx[4]);
-        else
+        // Check image dimensions
+        for (int i = 0; i < GFitsImageInx[0]; ++i) {
+             if (GFitsImageInx[i+1] < 0 || GFitsImageInx[i+1] >= self->naxes(i)) {
+                throw GException::out_of_range("__getitem__(int)",
+                                               "FITS image axis "+
+                                               gammalib::str(i)+" index",
+                                               GFitsImageInx[i+1],
+                                               self->naxes(i));
+            }
+        }
+        // Return pixel value
+        if (GFitsImageInx[0] == 1) {
+            return (*self)(GFitsImageInx[1]);
+        }
+        else if (GFitsImageInx[0] == 2) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2]);
+        }
+        else if (GFitsImageInx[0] == 3) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]);
+        }
+        else if (GFitsImageInx[0] == 4) {
+            return (*self)(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3],
+                           GFitsImageInx[4]);
+        }
+        else {
             throw GException::fits_wrong_image_operator("__getitem__(int)",
                                                         self->naxis(), GFitsImageInx[0]);
+        }
     }
     void __setitem__(int GFitsImageInx[], unsigned short value) {
-        if (GFitsImageInx[0] == 1)
+        if (GFitsImageInx[0] == 1) {
             self->at(GFitsImageInx[1]) = value;
-        else if (GFitsImageInx[0] == 2)
+        }
+        else if (GFitsImageInx[0] == 2) {
             self->at(GFitsImageInx[1], GFitsImageInx[2]) = value;
-        else if (GFitsImageInx[0] == 3)
-            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]) = value;
-        else if (GFitsImageInx[0] == 4)
-            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3], GFitsImageInx[4]) = value;
-        else
+        }
+        else if (GFitsImageInx[0] == 3) {
+            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3]) =
+                     value;
+        }
+        else if (GFitsImageInx[0] == 4) {
+            self->at(GFitsImageInx[1], GFitsImageInx[2], GFitsImageInx[3],
+                     GFitsImageInx[4]) = value;
+        }
+        else {
             throw GException::fits_wrong_image_operator("__setitem__(int)",
-                                                        self->naxis(), GFitsImageInx[0]);
+                                                        self->naxis(),
+                                                        GFitsImageInx[0]);
+        }
     }
     GFitsImageUShort copy() {
         return (*self);