diff --git a/PIL/ImImagePlugin.py b/PIL/ImImagePlugin.py
index 3371b303f..388015b7f 100644
--- a/PIL/ImImagePlugin.py
+++ b/PIL/ImImagePlugin.py
@@ -310,6 +310,7 @@ SAVE = {
     "I;16": ("L 16", "I;16"),
     "I;16L": ("L 16L", "I;16L"),
     "I;16B": ("L 16B", "I;16B"),
+    "I;16S": ("L 16S", "I;16S"),
     "F": ("L 32F", "F;32F"),
     "RGB": ("RGB", "RGB;L"),
     "RGBA": ("RGBA", "RGBA;L"),
diff --git a/PIL/Image.py b/PIL/Image.py
index 6e6927842..62972f5e7 100644
--- a/PIL/Image.py
+++ b/PIL/Image.py
@@ -238,7 +238,7 @@ _MODEINFO = {
     "LAB": ("RGB", "L", ("L", "A", "B")),
     "HSV": ("RGB", "L", ("H", "S", "V")),
 
-    # Experimental modes include I;16, I;16L, I;16B, RGBa, BGR;15, and
+    # Experimental modes include I;16, I;16L, I;16B, I;16S, RGBa, BGR;15, and
     # BGR;24.  Use these modes only if you know exactly what you're
     # doing...
 
diff --git a/PIL/ImageMode.py b/PIL/ImageMode.py
index b227f2127..3f638d5f5 100644
--- a/PIL/ImageMode.py
+++ b/PIL/ImageMode.py
@@ -50,6 +50,7 @@ def getmode(mode):
         modes["I;16"] = ModeDescriptor("I;16", "I", "L", "L")
         modes["I;16L"] = ModeDescriptor("I;16L", "I", "L", "L")
         modes["I;16B"] = ModeDescriptor("I;16B", "I", "L", "L")
+        modes["I;16S"] = ModeDescriptor("I;16S", "I", "L", "L")
         # set global mode cache atomically
         _modes = modes
     return _modes[mode]
diff --git a/Tests/test_mode_i16.py b/Tests/test_mode_i16.py
index d51847199..b150126f0 100644
--- a/Tests/test_mode_i16.py
+++ b/Tests/test_mode_i16.py
@@ -79,6 +79,7 @@ class TestModeI16(PillowTestCase):
         basic("I;16")
         basic("I;16B")
         basic("I;16L")
+        basic("I;16S")
 
         basic("I")
 
@@ -92,6 +93,7 @@ class TestModeI16(PillowTestCase):
         self.assertEqual(tobytes("L"), b"\x01")
         self.assertEqual(tobytes("I;16"), b"\x01\x00")
         self.assertEqual(tobytes("I;16B"), b"\x00\x01")
+        self.assertEqual(tobytes("I;16S"), b"\x01\x00")
         self.assertEqual(tobytes("I"), b"\x01\x00\x00\x00"[::order])
 
     def test_convert(self):
@@ -106,6 +108,10 @@ class TestModeI16(PillowTestCase):
         self.verify(im.convert("I;16B").convert("L"))
         self.verify(im.convert("I;16B").convert("I"))
 
+        self.verify(im.convert("I;16S"))
+        self.verify(im.convert("I;16S").convert("L"))
+        self.verify(im.convert("I;16S").convert("I"))
+
 
 if __name__ == '__main__':
     unittest.main()
diff --git a/libImaging/Access.c b/libImaging/Access.c
index 292968f1c..05eb10c7c 100644
--- a/libImaging/Access.c
+++ b/libImaging/Access.c
@@ -227,6 +227,7 @@ ImagingAccessInit()
     ADD("I;16", line_16, get_pixel_16L, put_pixel_16L);
     ADD("I;16L", line_16, get_pixel_16L, put_pixel_16L);
     ADD("I;16B", line_16, get_pixel_16B, put_pixel_16B);
+    ADD("I;16S", line_16, get_pixel_16L, put_pixel_16L);
     ADD("I;32L", line_32, get_pixel_32L, put_pixel_32L);
     ADD("I;32B", line_32, get_pixel_32B, put_pixel_32B);
     ADD("F", line_32, get_pixel_32, put_pixel_32);
diff --git a/libImaging/Convert.c b/libImaging/Convert.c
index b3e48e52b..f7c01a65d 100644
--- a/libImaging/Convert.c
+++ b/libImaging/Convert.c
@@ -49,7 +49,7 @@
 
 #ifndef round
 double round(double x) {
-  return floor(x+0.5);
+    return floor(x+0.5);
 }
 #endif
 
@@ -694,6 +694,17 @@ I_I16B(UINT8* out, const UINT8* in_, int xsize)
     }
 }
 
+static void
+I_I16S(UINT8* out, const UINT8* in_, int xsize)
+{
+    int x, v;
+    INT32* in = (INT32*) in_;
+    for (x = 0; x < xsize; x++, in++) {
+        v = CLIP16(*in);
+        *out++ = (UINT8) v;
+        *out++ = (UINT8) (v >> 8);
+    }
+}
 
 static void
 I16L_I(UINT8* out_, const UINT8* in, int xsize)
@@ -714,6 +725,15 @@ I16B_I(UINT8* out_, const UINT8* in, int xsize)
         *out++ = in[1] + ((int) in[0] << 8);
 }
 
+static void
+I16S_I(UINT8* out_, const UINT8* in, int xsize)
+{
+    int x;
+    INT32* out = (INT32*) out_;
+    for (x = 0; x < xsize; x++, in += 2)
+        *out++ = (INT16)(in[0] + ((int) in[1] << 8));
+}
+
 static void
 I16L_F(UINT8* out_, const UINT8* in, int xsize)
 {
@@ -733,6 +753,15 @@ I16B_F(UINT8* out_, const UINT8* in, int xsize)
         *out++ = (FLOAT32) (in[1] + ((int) in[0] << 8));
 }
 
+static void
+I16S_F(UINT8* out_, const UINT8* in, int xsize)
+{
+    int x;
+    FLOAT32* out = (FLOAT32*) out_;
+    for (x = 0; x < xsize; x++, in += 2)
+        *out++ = (FLOAT32) (INT16) (in[0] + ((int) in[1] << 8));
+}
+
 static void
 L_I16L(UINT8* out, const UINT8* in, int xsize)
 {
@@ -753,6 +782,16 @@ L_I16B(UINT8* out, const UINT8* in, int xsize)
     }
 }
 
+static void
+L_I16S(UINT8* out, const UINT8* in, int xsize)
+{
+    int x;
+    for (x = 0; x < xsize; x++, in++) {
+        *out++ = *in;
+        *out++ = 0;
+    }
+}
+
 static void
 I16L_L(UINT8* out, const UINT8* in, int xsize)
 {
@@ -775,6 +814,19 @@ I16B_L(UINT8* out, const UINT8* in, int xsize)
             *out++ = in[1];
 }
 
+static void
+I16S_L(UINT8* out, const UINT8* in, int xsize)
+{
+    int x;
+    for (x = 0; x < xsize; x++, in += 2)
+        if (in[1] & 0x80)
+            *out++ = 0;  /* Negative -> 0 */
+        else if (in[1] != 0)
+            *out++ = 255;  /* Greater than 255 -> 255 */
+        else
+            *out++ = in[0];
+}
+
 static struct {
     const char* from;
     const char* to;
@@ -873,9 +925,15 @@ static struct {
     { "L", "I;16B", L_I16B },
     { "I;16B", "L", I16B_L },
 
+    { "I", "I;16S", I_I16S },
+    { "I;16S", "I", I16S_I },
+    { "L", "I;16S", L_I16S },
+    { "I;16S", "L", I16S_L },
+
     { "I;16", "F", I16L_F },
     { "I;16L", "F", I16L_F },
     { "I;16B", "F", I16B_F },
+    { "I;16S", "F", I16S_F },
 
     { NULL }
 };
diff --git a/libImaging/Pack.c b/libImaging/Pack.c
index e6253fca4..f74e18e1b 100644
--- a/libImaging/Pack.c
+++ b/libImaging/Pack.c
@@ -614,6 +614,7 @@ static struct {
     {"I;16",    "I;16",         16,     copy2},
     {"I;16B",   "I;16B",        16,     copy2},
     {"I;16L",   "I;16L",        16,     copy2},
+    {"I;16S",   "I;16S",        16,     copy2},
     {"I;16",    "I;16N",        16,     packI16N_I16}, // LibTiff native->image endian.
     {"I;16L",   "I;16N",        16,     packI16N_I16},
     {"I;16B",   "I;16N",        16,     packI16N_I16B},
diff --git a/libImaging/Storage.c b/libImaging/Storage.c
index 72285970a..92c5c4e06 100644
--- a/libImaging/Storage.c
+++ b/libImaging/Storage.c
@@ -116,7 +116,8 @@ ImagingNewPrologueSubtype(const char *mode, int xsize, int ysize, int size)
         im->type = IMAGING_TYPE_INT32;
 
     } else if (strcmp(mode, "I;16") == 0 || strcmp(mode, "I;16L") == 0 \
-                           || strcmp(mode, "I;16B") == 0 || strcmp(mode, "I;16N") == 0)  {
+                           || strcmp(mode, "I;16B") == 0 || strcmp(mode, "I;16N") == 0 \
+                           || strcmp(mode, "I;16S") == 0)  {
         /* EXPERIMENTAL */
         /* 16-bit raw integer images */
         im->bands = 1;
diff --git a/libImaging/Unpack.c b/libImaging/Unpack.c
index c7b9a606c..183193983 100644
--- a/libImaging/Unpack.c
+++ b/libImaging/Unpack.c
@@ -1406,6 +1406,7 @@ static struct {
     {"I;16",    "I;16",         16,     copy2},
     {"I;16B",   "I;16B",        16,     copy2},
     {"I;16L",   "I;16L",        16,     copy2},
+    {"I;16S",   "I;16S",         16,     copy2},
 
     {"I;16", 	"I;16N",	    16,	    unpackI16N_I16}, // LibTiff native->image endian.
     {"I;16L", 	"I;16N",	    16,	    unpackI16N_I16}, // LibTiff native->image endian.