diff --git a/src/_backend_agg.cpp b/src/_backend_agg.cpp
index b088c97c9aa3..6473526b16eb 100644
--- a/src/_backend_agg.cpp
+++ b/src/_backend_agg.cpp
@@ -2518,9 +2518,11 @@ Py::Object _backend_agg_module::new_renderer(const Py::Tuple &args,
     unsigned int height = (int)Py::Int(args[1]);
     double dpi = Py::Float(args[2]);
 
-    if (width > 1 << 15 || height > 1 << 15)
+    char msg [256];
+    if (width > INT_MAX || height > INT_MAX)
     {
-        throw Py::ValueError("width and height must each be below 32768");
+        sprintf(msg, "width and height must each be below %d", INT_MAX);
+        throw Py::ValueError(msg);
     }
 
     if (dpi <= 0.0)
diff --git a/src/_backend_agg.h b/src/_backend_agg.h
index 100ac4819f73..ad302e329e3a 100644
--- a/src/_backend_agg.h
+++ b/src/_backend_agg.h
@@ -7,6 +7,7 @@
 #ifndef __BACKEND_AGG_H
 #define __BACKEND_AGG_H
 #include <utility>
+#include <climits>
 #include "CXX/Extensions.hxx"
 
 #include "agg_arrowhead.h"
@@ -59,10 +60,15 @@ typedef agg::renderer_scanline_aa_solid<renderer_base> renderer_aa;
 typedef agg::renderer_scanline_bin_solid<renderer_base> renderer_bin;
 typedef agg::rasterizer_scanline_aa<agg::rasterizer_sl_clip_dbl> rasterizer;
 
-typedef agg::scanline_p8 scanline_p8;
-typedef agg::scanline_bin scanline_bin;
+// typedef agg::scanline_p8 scanline_p8; // 16 bits display rendering
+// typedef agg::scanline_bin scanline_bin; // 16 bits display rendering
+typedef agg::scanline32_p8 scanline_p8; // 32 bits display rendering
+typedef agg::scanline32_bin scanline_bin; // 32 bits display rendering
+
 typedef agg::amask_no_clip_gray8 alpha_mask_type;
-typedef agg::scanline_u8_am<alpha_mask_type> scanline_am;
+
+// typedef agg::scanline_u8_am<alpha_mask_type> scanline_am; // 16 bits display rendering
+typedef agg::scanline32_u8_am<alpha_mask_type> scanline_am; // 32 bits display rendering
 
 typedef agg::renderer_base<agg::pixfmt_gray8> renderer_base_alpha_mask_type;
 typedef agg::renderer_scanline_aa_solid<renderer_base_alpha_mask_type> renderer_alpha_mask_type;
diff --git a/src/_image.cpp b/src/_image.cpp
index 73f2624c772c..700e3ca56591 100644
--- a/src/_image.cpp
+++ b/src/_image.cpp
@@ -786,9 +786,11 @@ _image_module::from_images(const Py::Tuple& args)
     size_t numrows = (long)Py::Int(args[0]);
     size_t numcols = (long)Py::Int(args[1]);
 
-    if (numrows >= 32768 || numcols >= 32768)
+    char msg [256];
+    if (numrows >= INT_MAX || numcols >= INT_MAX)
     {
-        throw Py::RuntimeError("numrows and numcols must both be less than 32768");
+        sprintf(msg, "numrows and numcols must both be less than %d", INT_MAX);
+        throw Py::ValueError(msg);
     }
 
     Py::SeqBase<Py::Object> tups = args[2];
@@ -1268,9 +1270,11 @@ _image_module::frombuffer(const Py::Tuple& args)
     size_t x = (long)Py::Int(args[1]);
     size_t y = (long)Py::Int(args[2]);
 
-    if (x >= 32768 || y >= 32768)
+    char msg [256];
+    if (x >= INT_MAX || y >= INT_MAX)
     {
-        throw Py::ValueError("x and y must both be less than 32768");
+        sprintf(msg, "numrows and numcols must both be less than %d", INT_MAX);
+        throw Py::ValueError(msg);
     }
 
     int isoutput = Py::Int(args[3]);
@@ -1576,9 +1580,11 @@ _image_module::pcolor(const Py::Tuple& args)
     Py::Tuple bounds = args[5];
     unsigned int interpolation = (unsigned long)Py::Int(args[6]);
 
-    if (rows >= 32768 || cols >= 32768)
+    char msg [256];
+    if (rows >= INT_MAX || cols >= INT_MAX)
     {
-        throw Py::ValueError("rows and cols must both be less than 32768");
+        sprintf(msg, "rows and cols must both be less than %d", INT_MAX);
+        throw Py::ValueError(msg);
     }
 
     if (bounds.length() != 4)
@@ -1822,11 +1828,15 @@ _image_module::pcolor2(const Py::Tuple& args)
     Py::Tuple bounds = args[5];
     Py::Object bgp = args[6];
 
-    if (rows >= 32768 || cols >= 32768)
+    char msg [256];
+    if (rows >= INT_MAX || cols >= INT_MAX)
     {
-        throw Py::ValueError("rows and cols must both be less than 32768");
+        sprintf(msg, "rows and cols must both be less than %d", INT_MAX);
+        throw Py::ValueError(msg);
     }
 
+
+
     if (bounds.length() != 4)
     {
         throw Py::TypeError("Incorrect number of bounds (4 expected)");
diff --git a/src/_image.h b/src/_image.h
index aa0de94174cd..cf7af5385aa6 100644
--- a/src/_image.h
+++ b/src/_image.h
@@ -7,6 +7,7 @@
 #ifndef _IMAGE_H
 #define _IMAGE_H
 #include <utility>
+#include <climits>
 #include "Python.h"
 
 #include "agg_trans_affine.h"
diff --git a/src/cntr.c b/src/cntr.c
index 4448714b6a59..1781b2f99419 100644
--- a/src/cntr.c
+++ b/src/cntr.c
@@ -183,7 +183,8 @@
 
 /* the data about edges, zones, and points -- boundary or not, exists
  * or not, z value 0, 1, or 2 -- is kept in a mesh sized data array */
-typedef short Cdata;
+// typedef short Cdata; // 16 bits display rendering
+typedef int Cdata; // 32 bits display rendering
 
 /* information to decide on correct contour direction in saddle zones
  * is stored in a mesh sized array.  Only those entries corresponding