diff --git a/src/osgPlugins/pnm/ReaderWriterPNM.cpp b/src/osgPlugins/pnm/ReaderWriterPNM.cpp
index 6ac775689..5da6bb9f6 100644
--- a/src/osgPlugins/pnm/ReaderWriterPNM.cpp
+++ b/src/osgPlugins/pnm/ReaderWriterPNM.cpp
@@ -14,173 +14,129 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include <sstream>
+
 using namespace osg;
+
 template <class T>
-    unsigned char* read_bitmap_ascii(FILE* fp, int width, int height)
+    unsigned char* read_bitmap_ascii(std::istream& fin, int width, int height)
 {
     T* data = new T[width*height];
-
-    T* dst = data;
     T* end = data + width*height;
 
-    while(dst < end)
+    int x = 0;
+    T* dst = end - width;
+    int value = 0;
+
+    while(dst >= data)
     {
-        T value = 0;
-
-        // read in characters looking for '0's and '1's, these
-        // values map to 255 and 0. Any other characters
-        // are silently ignored.
-        while(1)
+        fin >> value;
+        if (!fin.good())
         {
-            int ch = fgetc(fp);
-            if (feof(fp) || ferror(fp))
-            {
-                delete [] data;
-                return NULL;
-            }
-
-            if (ch == '0')
-            {
-                value = 255;
-                break;
-            }
-            else if (ch == '1')
-            {
-                value = 0;
-                break;
-            }
+            delete [] data;
+            return NULL;
         }
 
-        // place value in the image
-        *(dst++) = value;
+        // place value in the image. 0 is white and anything else is black.
+        *(dst++) = value ? 0 : 255;
+
+        // At end of each row, jump back two rows
+        ++x;
+        if (x == width)
+        {
+            x = 0;
+            dst -= 2*width;
+        }
     }
 
     return reinterpret_cast<unsigned char*>(data);
 }
 
 template <class T>
-    unsigned char* read_grayscale_ascii(FILE* fp, int width, int height)
+    unsigned char* read_grayscale_ascii(std::istream& fin, int width, int height, int max_value)
 {
     T* data = new T[width*height];
-
-    T* dst = data;
     T* end = data + width*height;
 
-    while(dst < end)
+    int x = 0;
+    T* dst = end - width;
+    int value = 0;
+    float max = (sizeof(T) == 1) ? 255.0 : 65535.0;
+
+    while(dst >= data)
     {
-        int ch;
-        T value = 0;
-
-        // read and discard any whitespace
-        // until a digit is reached
-        do
+        fin >> value;
+        if (!fin.good())
         {
-            ch = fgetc(fp);
-            if (feof(fp) || ferror(fp))
-            {
-                delete [] data;
-                return NULL;
-            }
+            delete [] data;
+            return NULL;
         }
-        while(!isdigit(ch));
-
-        // continue reading digits and incrementally
-        // construct the integer value
-        do
-        {
-            value = 10*value + (ch - '0');
-            ch = fgetc(fp);
-            if (feof(fp) || ferror(fp))
-            {
-                delete [] data;
-                return NULL;
-            }
-        }
-        while(isdigit(ch));
 
         // place value in the image
-        *(dst++) = value;
+        *(dst++) = T(float(value)/float(max_value)*max);
+
+        // At end of each row, jump back two rows
+        ++x;
+        if (x == width)
+        {
+            x = 0;
+            dst -= 2*width;
+        }
     }
 
     return reinterpret_cast<unsigned char*>(data);
 }
 
 template <class T>
-    unsigned char* read_color_ascii(FILE* fp, int width, int height)
+    unsigned char* read_color_ascii(std::istream& fin, int width, int height, int max_value)
 {
     T* data = new T[3*width*height];
-
-    T* dst = data;
     T* end = data + 3*width*height;
 
-    osg::notify(osg::NOTICE)<<"Width = "<<width<<std::endl;
-    osg::notify(osg::NOTICE)<<"Height = "<<height<<std::endl;
-    
-    unsigned int numRead = 0;
+    int x = 0;
+    T* dst = end - 3*width;
+    int value = 0;
+    float max = (sizeof(T) == 1) ? 255.0 : 65535.0;
 
-    while(dst < end)
+    while(dst >= data)
     {
-        int ch;
-        T value = 0;
-
-        // read and discard any whitespace
-        // until a digit is reached
-        do
+        fin >> value;
+        if (!fin.good())
         {
-            ch = fgetc(fp);
-            if (feof(fp) || ferror(fp))
-            {
-                osg::notify(osg::NOTICE)<<"Error 1 "<<numRead<<std::endl;
-
-                delete [] data;
-                return NULL;
-            }
+            delete [] data;
+            return NULL;
         }
-        while(!isdigit(ch));
-
-        // continue reading digits and incrementally
-        // construct the integer value
-        do
-        {
-            value = 10*value + (ch - '0');
-            ch = fgetc(fp);
-            if (feof(fp) || ferror(fp))
-            {
-                osg::notify(osg::NOTICE)<<"Error 2"<<std::endl;
-
-                delete [] data;
-                return NULL;
-            }
-        }
-        while(isdigit(ch));
-
-        ++numRead;
 
         // place value in the image
-        *(dst++) = value;
-    }
+        *(dst++) = T(float(value)/float(max_value)*max);
 
-    osg::notify(osg::NOTICE)<<"Completed"<<std::endl;
+        // At end of the row, jump back two rows
+        ++x;
+        if (x == width*3)
+        {
+            x = 0;
+            dst -= 6*width;
+        }
+    }
 
     return reinterpret_cast<unsigned char*>(data);
 }
 
 template <class T>
-    unsigned char* read_bitmap_binary(FILE* fp, int width, int height)
+    unsigned char* read_bitmap_binary(std::istream& fin, int width, int height)
 {
     T* data = new T[width*height];
 
-    for(int y = 0; y < height; y++)
+    for(int y = height-1; y >= 0; --y)
     {
         T* dst = data + (y+0)*width;
         T* end = data + (y+1)*width;
 
         while(dst < end)
         {
-            unsigned char b = fgetc(fp);
-            if (feof(fp) || ferror(fp))
+            unsigned char b = (unsigned char) fin.get();
+            if (!fin.good())
             {
-                fclose(fp);
                 delete [] data;
                 return NULL;
             }
@@ -198,48 +154,58 @@ template <class T>
 }
 
 template <class T>
-    unsigned char* read_grayscale_binary(FILE* fp, int width, int height)
+    unsigned char* read_grayscale_binary(std::istream& fin, int width, int height)
 {
     T* data = new T[width*height];
 
-    if (fread(data, sizeof(T)*width*height, 1, fp) != 1)
+    for(int y = height-1; y >= 0; --y)
     {
-        fclose(fp);
-        delete [] data;
-        return NULL;
+        T* dst = data + y*width;
+        fin.read((char*)dst, sizeof(T)*width);
+        if (!fin.good())
+        {
+            delete [] data;
+            return NULL;
+        }
     }
 
     // if the machine is little endian swap the bytes around
-    if (sizeof(T) > 1 && getCpuByteOrder() == osg::LittleEndian)
+    if (sizeof(T) == 2 && getCpuByteOrder() == osg::LittleEndian)
     {
-        for(int i = 0; i < width*height; i++)
+        unsigned char *bs = reinterpret_cast<unsigned char *>(data);
+        unsigned char *end = bs + sizeof(T)*width*height;
+        for (; bs < end; bs += 2)
         {
-            unsigned char* bs = (unsigned char*)(&data[i]);
             std::swap(bs[0], bs[1]);
         }
     }
 
-    return reinterpret_cast<unsigned char*>(data);
+    return reinterpret_cast<unsigned char *>(data);
 }
 
 template <class T>
-    unsigned char* read_color_binary(FILE* fp, int width, int height)
+    unsigned char* read_color_binary(std::istream& fin, int width, int height)
 {
     T* data = new T[3*width*height];
 
-    if (fread(data, 3*sizeof(T)*width*height, 1, fp) != 1)
+    for(int y = height-1; y >= 0; --y)
     {
-        fclose(fp);
-        delete [] data;
-        return NULL;
+        T* dst = data + y*3*width;
+        fin.read((char*)dst, sizeof(T)*3*width);
+        if (!fin.good())
+        {
+            delete [] data;
+            return NULL;
+        }
     }
 
     // if the machine is little endian swap the bytes around
-    if (sizeof(T) > 1 && getCpuByteOrder() == osg::LittleEndian)
+    if (sizeof(T) == 2 && getCpuByteOrder() == osg::LittleEndian)
     {
-        for(int i = 0; i < 3*width*height; i++)
+        unsigned char *bs = reinterpret_cast<unsigned char *>(data);
+        unsigned char *end = bs + sizeof(T)*3*width*height;
+        for (; bs < end; bs+=2)
         {
-            unsigned char* bs = (unsigned char*)(&data[i]);
             std::swap(bs[0], bs[1]);
         }
     }
@@ -260,32 +226,23 @@ class ReaderWriterPNM : public osgDB::ReaderWriter
         
         virtual const char* className() const { return "PNM Image Reader/Writer"; }
 
-        virtual ReadResult readImage(const std::string& file, const osgDB::ReaderWriter::Options* options) const
+        virtual ReadResult readImage(std::istream& fin, const osgDB::ReaderWriter::Options* options=NULL) const
         {
-            std::string ext = osgDB::getLowerCaseFileExtension(file);
-            if (!acceptsExtension(ext)) return ReadResult::FILE_NOT_HANDLED;
-
-            std::string fileName = osgDB::findDataFile( file, options );
-            if (fileName.empty()) return ReadResult::FILE_NOT_FOUND;
-
-            FILE *fp = NULL;
-            char line[300];
             int ppmtype = 0;    /* P1, P2, etc. */
             int width = 0;
             int height = 0;
             int max_value = 0;
 
-            // Open file.
-            fp = osgDB::fopen(fileName.c_str(), "rb");
-
             // Read header items.
+            std::string line;
             int row;
             for (row = 1; row <= 3; row++)
             {
-                if ( fgets(line, 300, fp) == NULL)
-                    break;
+                getline(fin, line);
+                if (!fin.good())
+                    return ReadResult::ERROR_IN_READING_FILE;
 
-                char *cp = line;
+                const char *cp = line.c_str();
                 while (*cp && isspace(*cp))
                     cp++;
                 if (! *cp || *cp == '#')
@@ -303,12 +260,10 @@ class ReaderWriterPNM : public osgDB::ReaderWriter
                 }
                 else if (row == 2)
                 {
-                    // Get the image size.
-                    width = atoi(line);
-                    char *cp = line + strspn(line, "\t \n\r");
-                    cp += strspn(cp, "0123456789");
-                    cp += strspn(line, "\t \n\r");
-                    height = atoi(cp);
+                    std::istringstream istr(line);
+
+                    istr >> width;
+                    istr >> height;
 
                     // pbm files don't have row 3
                     if (ppmtype == 1 || ppmtype == 4)
@@ -320,7 +275,8 @@ class ReaderWriterPNM : public osgDB::ReaderWriter
                 else if (row == 3)
                 {
                     // Get the maximum value
-                    max_value = atoi(line);
+                    std::istringstream istr(line);
+                    istr >> max_value;
                 }
             }
 
@@ -329,7 +285,6 @@ class ReaderWriterPNM : public osgDB::ReaderWriter
                 max_value <= 0 || max_value > 65535 ||
                 ppmtype < 1 || ppmtype > 6)
             {
-                fclose(fp);
                 return ReadResult::ERROR_IN_READING_FILE;
             }
 
@@ -342,29 +297,24 @@ class ReaderWriterPNM : public osgDB::ReaderWriter
                 dataType = GL_UNSIGNED_SHORT;
                 switch(ppmtype)
                 {
-                    case 1:    // bitmap ascii
-                        pixelFormat = GL_LUMINANCE;
-                        data = read_bitmap_ascii<unsigned short>(fp, width, height);
-                        break;
                     case 2:    // grayscale ascii
                         pixelFormat = GL_LUMINANCE;
-                        data = read_grayscale_ascii<unsigned short>(fp, width, height);
+                        data = read_grayscale_ascii<unsigned short>(fin, width, height, max_value);
                         break;
                     case 3:    // color ascii
                         pixelFormat = GL_RGB;
-                        data = read_color_ascii<unsigned short>(fp, width, height);
-                        break;
-                    case 4:    // bitmap binary
-                        pixelFormat = GL_LUMINANCE;
-                        data = read_bitmap_binary<unsigned short>(fp, width, height);
+                        data = read_color_ascii<unsigned short>(fin, width, height, max_value);
                         break;
                     case 5:    // grayscale binary
                         pixelFormat = GL_LUMINANCE;
-                        data = read_grayscale_binary<unsigned short>(fp, width, height);
+                        data = read_grayscale_binary<unsigned short>(fin, width, height);
                         break;
                     case 6:    // color binary
                         pixelFormat = GL_RGB;
-                        data = read_color_binary<unsigned short>(fp, width, height);
+                        data = read_color_binary<unsigned short>(fin, width, height);
+                        break;
+                    default:
+                        return ReadResult::ERROR_IN_READING_FILE;
                         break;
                 }
             }
@@ -375,44 +325,41 @@ class ReaderWriterPNM : public osgDB::ReaderWriter
                 {
                     case 1:    // bitmap ascii
                         pixelFormat = GL_LUMINANCE;
-                        data = read_bitmap_ascii<unsigned char>(fp, width, height);
+                        data = read_bitmap_ascii<unsigned char>(fin, width, height);
                         break;
                     case 2:    // grayscale ascii
                         pixelFormat = GL_LUMINANCE;
-                        data = read_grayscale_ascii<unsigned char>(fp, width, height);
+                        data = read_grayscale_ascii<unsigned char>(fin, width, height, max_value);
                         break;
                     case 3:    // color ascii
                         pixelFormat = GL_RGB;
-                        data = read_color_ascii<unsigned char>(fp, width, height);
+                        data = read_color_ascii<unsigned char>(fin, width, height, max_value);
                         break;
                     case 4:    // bitmap binary
                         pixelFormat = GL_LUMINANCE;
-                        data = read_bitmap_binary<unsigned char>(fp, width, height);
+                        data = read_bitmap_binary<unsigned char>(fin, width, height);
                         break;
                     case 5:    // grayscale binary
                         pixelFormat = GL_LUMINANCE;
-                        data = read_grayscale_binary<unsigned char>(fp, width, height);
+                        data = read_grayscale_binary<unsigned char>(fin, width, height);
                         break;
                     case 6:    // color binary
                         pixelFormat = GL_RGB;
-                        data = read_color_binary<unsigned char>(fp, width, height);
+                        data = read_color_binary<unsigned char>(fin, width, height);
+                        break;
+                    default:
+                        return ReadResult::ERROR_IN_READING_FILE;
                         break;
                 }
             }
 
             if (data == NULL)
             {
-                if (fp)
-                    fclose(fp);
                 return ReadResult::FILE_NOT_HANDLED;
             }
 
-            if (fp)
-                fclose(fp);
-
             osg::Image* pOsgImage = new osg::Image();
 
-            pOsgImage->setFileName(fileName.c_str());
             pOsgImage->setImage(width, height, 1,
                 pixelFormat,
                 pixelFormat,
@@ -428,6 +375,24 @@ class ReaderWriterPNM : public osgDB::ReaderWriter
             return pOsgImage;
         }
 
+        virtual ReadResult readImage(const std::string& file, const osgDB::ReaderWriter::Options* options) const
+        {
+            std::string ext = osgDB::getLowerCaseFileExtension(file);
+            if (!acceptsExtension(ext)) return ReadResult::FILE_NOT_HANDLED;
+
+            std::string fileName = osgDB::findDataFile( file, options );
+            if (fileName.empty()) return ReadResult::FILE_NOT_FOUND;
+
+            std::ifstream fin(fileName.c_str());
+            if (!fin.good())
+                return ReadResult::ERROR_IN_READING_FILE;
+
+            ReadResult rr = readImage(fin, options);
+            fin.close();
+            if (rr.validImage()) rr.getImage()->setFileName(file);
+            return rr;
+        }
+
         virtual WriteResult writeImage(const osg::Image& image,std::ostream& fout,const osgDB::ReaderWriter::Options* options) const
         {
             bool ascii = (options && options->getOptionString().find("ascii")!=std::string::npos);