diff -u -r metapixel-1.0.2/rwimg/rwgif.c metapixel-1.0.2-rwimg/rwimg/rwgif.c
--- metapixel-1.0.2/rwimg/rwgif.c	2006-12-10 17:59:54.000000000 +0000
+++ metapixel-1.0.2-rwimg/rwimg/rwgif.c	2015-08-27 16:46:56.402621517 +0100
@@ -54,7 +54,7 @@
     
     assert(data != 0);
     
-    data->file = DGifOpenFileName(filename);
+    data->file = DGifOpenFileName(filename, NULL);
     
     assert(data->file !=0);
         
@@ -137,7 +137,7 @@
     }
     free(buffer);
     
-    assert(DGifCloseFile(data->file) == GIF_OK);
+    assert(DGifCloseFile(data->file, NULL) == GIF_OK);
     
     return data;
 }
diff -u -r metapixel-1.0.2/rwimg/rwpng.c metapixel-1.0.2-rwimg/rwimg/rwpng.c
--- metapixel-1.0.2/rwimg/rwpng.c	2006-12-10 17:59:54.000000000 +0000
+++ metapixel-1.0.2-rwimg/rwimg/rwpng.c	2015-08-27 16:44:12.337891932 +0100
@@ -35,6 +35,7 @@
     png_structp png_ptr;
     png_infop info_ptr, end_info;
     int row_stride;
+    int pixel_stride;
     int have_read;
 } png_data_t;
 
@@ -42,10 +43,11 @@
 open_png_file_reading (const char *filename, int *width, int *height)
 {
     png_data_t *data = (png_data_t*)malloc(sizeof(png_data_t));
+    int bit_depth, color_type;
 
     assert(data != 0);
 
-    data->file = fopen(filename, "r");
+    data->file = fopen(filename, "rb");
     assert(data->file != 0);
 
     data->png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0);
@@ -57,19 +59,41 @@
     data->end_info = png_create_info_struct(data->png_ptr);
     assert(data->end_info != 0);
 
-    if (setjmp(data->png_ptr->jmpbuf))
+    if (setjmp (png_jmpbuf (data->png_ptr)))
 	assert(0);
 
     png_init_io(data->png_ptr, data->file);
 
     png_read_info(data->png_ptr, data->info_ptr);
 
-    *width = data->info_ptr->width;
-    *height = data->info_ptr->height;
+    *width = png_get_image_width (data->png_ptr, data->info_ptr);
+    *height = png_get_image_height (data->png_ptr, data->info_ptr);
 
-    assert(data->info_ptr->bit_depth == 8 || data->info_ptr->bit_depth == 16);
-    assert(data->info_ptr->color_type == PNG_COLOR_TYPE_RGB || data->info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA);
-    assert(data->info_ptr->interlace_type == PNG_INTERLACE_NONE);
+    bit_depth = png_get_bit_depth (data->png_ptr, data->info_ptr);
+    if (bit_depth != 8 && bit_depth != 16)
+    {
+	fprintf(stderr, "PNG files are only supported with bit depths 8 and 16.\n");
+	/* FIXME: free stuff */
+	return 0;
+    }
+
+    color_type = png_get_color_type (data->png_ptr, data->info_ptr);
+    if (color_type != PNG_COLOR_TYPE_RGB
+	&& color_type != PNG_COLOR_TYPE_RGB_ALPHA
+	&& color_type != PNG_COLOR_TYPE_GRAY
+	&& color_type != PNG_COLOR_TYPE_GRAY_ALPHA)
+    {
+	fprintf(stderr, "PNG files are only supported in RGB and Gray, with or without alpha.\n");
+	/* FIXME: free stuff */
+	return 0;
+    }
+
+    if (png_get_interlace_type (data->png_ptr, data->info_ptr) != PNG_INTERLACE_NONE)
+    {
+	fprintf(stderr, "Interlaced PNG files are not supported.\n");
+	/* FIXME: free stuff */
+	return 0;
+    }
 
     data->have_read = 0;
 
@@ -83,30 +107,44 @@
     int i;
     int bps, spp;
     unsigned char *row;
+    int color_type, width;
 
-    if (setjmp(data->png_ptr->jmpbuf))
+    if (setjmp (png_jmpbuf (data->png_ptr)))
 	assert(0);
 
-    if (data->info_ptr->color_type == PNG_COLOR_TYPE_RGB)
+    color_type = png_get_color_type (data->png_ptr, data->info_ptr);
+    if (color_type == PNG_COLOR_TYPE_GRAY)
+	spp = 1;
+    else if (color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+	spp = 2;
+    else if (color_type == PNG_COLOR_TYPE_RGB)
 	spp = 3;
     else
 	spp = 4;
 
-    if (data->info_ptr->bit_depth == 16)
+    if (png_get_bit_depth (data->png_ptr, data->info_ptr) == 16)
 	bps = 2;
     else
 	bps = 1;
 
-    row = (unsigned char*)malloc(data->info_ptr->width * spp * bps);
+    width = png_get_image_width (data->png_ptr, data->info_ptr);
+    row = (unsigned char*)malloc (width * spp * bps);
 
     for (i = 0; i < num_lines; ++i)
     {
 	int j, channel;
 
 	png_read_row(data->png_ptr, (png_bytep)row, 0);
-	for (j = 0; j < data->info_ptr->width; ++j)
-	    for (channel = 0; channel < 3; ++channel)
-		lines[i * data->info_ptr->width * 3 + j * 3 + channel] = row[j * spp * bps + channel * bps];
+
+	if (spp <= 2)
+	    for (j = 0; j < width; ++j)
+		for (channel = 0; channel < 3; ++channel)
+		    lines[i * width * 3 + j * 3 + channel] = row[j * spp * bps];
+	else
+	    for (j = 0; j < width; ++j)
+		for (channel = 0; channel < 3; ++channel)
+		    lines[i * width * 3 + j * 3 + channel]
+			= row[j * spp * bps + channel * bps];
     }
 
     free(row);
@@ -119,7 +157,7 @@
 {
     png_data_t *data = (png_data_t*)_data;
 
-    if (setjmp(data->png_ptr->jmpbuf))
+    if (setjmp (png_jmpbuf (data->png_ptr)))
 	assert(0);
 
     if (data->have_read)
@@ -137,9 +175,9 @@
 
     assert(data != 0);
 
-    assert(pixel_stride == 3 || pixel_stride == 4);
+    assert(pixel_stride >= 3);
 
-    data->file = fopen(filename, "w");
+    data->file = fopen(filename, "wb");
     assert(data->file != 0);
 
     data->png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0);
@@ -148,7 +186,7 @@
     data->info_ptr = png_create_info_struct(data->png_ptr);
     assert(data->info_ptr != 0);
 
-    if (setjmp(data->png_ptr->jmpbuf))
+    if (setjmp (png_jmpbuf (data->png_ptr)))
 	assert(0);
 
     if (pixel_stride == 4)
@@ -156,21 +194,13 @@
 
     png_init_io(data->png_ptr, data->file);
 
-    data->info_ptr->width = width;
-    data->info_ptr->height = height;
-    data->info_ptr->valid = 0;
-    data->info_ptr->rowbytes = width * 3;
-    data->info_ptr->palette = 0;
-    data->info_ptr->num_palette = 0;
-    data->info_ptr->num_trans = 0;
-    data->info_ptr->bit_depth = 8;
-    data->info_ptr->color_type = PNG_COLOR_TYPE_RGB;
-    data->info_ptr->compression_type = PNG_COMPRESSION_TYPE_DEFAULT;
-    data->info_ptr->filter_type = PNG_FILTER_TYPE_DEFAULT;
-    data->info_ptr->interlace_type = PNG_INTERLACE_NONE;
+    png_set_IHDR (data->png_ptr, data->info_ptr,
+		  width, height, 8, PNG_COLOR_TYPE_RGB,
+		  PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
 
     png_write_info(data->png_ptr, data->info_ptr);
 
+    data->pixel_stride = pixel_stride;
     data->row_stride = row_stride;
 
     return data;
@@ -180,13 +210,45 @@
 png_write_lines (void *_data, unsigned char *lines, int num_lines)
 {
     png_data_t *data = (png_data_t*)_data;
+    unsigned char *packed_line;
     int i;
+    int width;
 
-    if (setjmp(data->png_ptr->jmpbuf))
+    if (setjmp (png_jmpbuf (data->png_ptr)))
 	assert(0);
 
+    width = png_get_image_width (data->png_ptr, data->info_ptr);
+    if (data->pixel_stride != 3)
+    {
+	packed_line = (unsigned char*)malloc(width * 3);
+	assert(packed_line != 0);
+    }
+    else
+	packed_line = 0;
+
     for (i = 0; i < num_lines; ++i)
-	png_write_row(data->png_ptr, (png_bytep)(lines + i * data->row_stride));
+    {
+	unsigned char *p = lines + i * data->row_stride;
+
+	if (packed_line != 0)
+	{
+	    int j;
+
+	    for (j = 0; j < width; ++j)
+	    {
+		packed_line[j * 3 + 0] = p[j * data->pixel_stride + 0];
+		packed_line[j * 3 + 1] = p[j * data->pixel_stride + 1];
+		packed_line[j * 3 + 2] = p[j * data->pixel_stride + 2];
+	    }
+
+	    p = packed_line;
+	}
+
+	png_write_row(data->png_ptr, (png_bytep)p);
+    }
+
+    if (packed_line != 0)
+	free(packed_line);
 }
 
 void
@@ -194,7 +256,7 @@
 {
     png_data_t *data = (png_data_t*)_data;
 
-    if (setjmp(data->png_ptr->jmpbuf))
+    if (setjmp (png_jmpbuf (data->png_ptr)))
 	assert(0);
 
     png_write_end(data->png_ptr, data->info_ptr);