The functions ImageCreateFromPng, and ImagePng are missing
so generated grahics cannot be used with GD1.6 and above.
Please find attached a diff which adds these functions.

Hope this help - Drew

diff -rNc php-3.0.12/functions/gd.c php-3.0.12-png/functions/gd.c
*** php-3.0.12/functions/gd.c	Sat Jul 17 09:11:15 1999
--- php-3.0.12-png/functions/gd.c	Wed Aug  4 13:03:45 1999
***************
*** 132,137 ****
--- 132,140 ----
  	/* GIF support is gone from gd-1.6 */
  	{"imagecreatefromgif",		php3_imagecreatefromgif,	NULL},
  	{"imagegif",				php3_imagegif,				NULL},
+ #else
+ 	{"imagecreatefrompng",		php3_imagecreatefrompng,	NULL},
+ 	{"imagepng",				php3_imagepng,				NULL},
  #endif
  	{"imagedestroy",			php3_imagedestroy,			NULL},
  	{"imagefill",				php3_imagefill,				NULL},
***************
*** 481,486 ****
--- 484,531 ----
  	RETURN_LONG(ind);
  }
  /* }}} */
+ #else
+ /* {{{ proto int imagecreatefrompng(string filename)
+ Create a new image from file or URL */
+ void php3_imagecreatefrompng (INTERNAL_FUNCTION_PARAMETERS) {
+ 	pval *file;
+ 	int ind;
+ 	gdImagePtr im;
+ 	char *fn=NULL;
+ 	FILE *fp;
+ 	int issock=0, socketd=0;
+ 	GD_TLS_VARS;
+ 
+ 	if (ARG_COUNT(ht) != 1 || getParameters(ht, 1, &file) == FAILURE) {
+ 		WRONG_PARAM_COUNT;
+ 	}
+ 
+ 	convert_to_string(file);
+ 
+ 	fn = file->value.str.val;
+ 
+ #if WIN32|WINNT
+ 	fp = fopen(file->value.str.val, "rb");
+ #else
+ 	fp = php3_fopen_wrapper(file->value.str.val, "r", IGNORE_PATH|IGNORE_URL_WIN, &issock, &socketd);
+ #endif
+ 	if (!fp) {
+ 		php3_strip_url_passwd(fn);
+ 		php3_error(E_WARNING,
+ 					"ImageCreateFromPng: Unable to open %s for reading", fn);
+ 		RETURN_FALSE;
+ 	}
+ 
+ 	im = gdImageCreateFromPng (fp);
+ 
+ 	fflush(fp);
+ 	fclose(fp);
+ 
+ 	ind = php3_list_insert(im, GD_GLOBAL(le_gd));
+ 
+ 	RETURN_LONG(ind);
+ }
+ /* }}} */
  #endif
  
  /* {{{ proto int imagedestroy(int im)
***************
*** 851,856 ****
--- 896,978 ----
  
  		if (output) {
  			gdImageGif (im, tmp);
+ 			fseek(tmp, 0, SEEK_SET);
+ #if APACHE && defined(CHARSET_EBCDIC)
+ 			/* This is a binary file already: avoid EBCDIC->ASCII conversion */
+ 			ap_bsetflag(php3_rqst->connection->client, B_EBCDIC2ASCII, 0);
+ #endif
+ 			while ((b = fread(buf, 1, sizeof(buf), tmp)) > 0) {
+ 				php3_write(buf, b);
+ 			}
+ 		}
+ 
+ 		fclose(tmp);
+ 		/* the temporary file is automatically deleted */
+ 	}
+ 
+ 	RETURN_TRUE;
+ }
+ /* }}} */
+ #else
+ /* {{{ proto int imagepng(int im, string filename)
+ Output image to browser or file */
+ void php3_imagepng (INTERNAL_FUNCTION_PARAMETERS) {
+ 	pval *imgind, *file;
+ 	gdImagePtr im;
+ 	char *fn=NULL;
+ 	FILE *fp;
+ 	int argc;
+ 	int ind_type;
+ 	int output=1;
+ 	GD_TLS_VARS;
+ 
+ 	argc = ARG_COUNT(ht);
+ 	if (argc < 1 || argc > 2 || getParameters(ht, argc, &imgind, &file) == FAILURE) {
+ 		WRONG_PARAM_COUNT;
+ 	}
+ 
+ 	convert_to_long(imgind);
+ 
+ 	if (argc == 2) {
+ 		convert_to_string(file);
+ 		fn = file->value.str.val;
+ 		if (!fn || fn == empty_string || _php3_check_open_basedir(fn)) {
+ 			php3_error(E_WARNING, "ImagePng: Invalid filename");
+ 			RETURN_FALSE;
+ 		}
+ 	}
+ 
+ 	im = php3_list_find(imgind->value.lval, &ind_type);
+ 	if (!im || ind_type != GD_GLOBAL(le_gd)) {
+ 		php3_error(E_WARNING, "ImagePng: unable to find image pointer");
+ 		RETURN_FALSE;
+ 	}
+ 
+ 	if (argc == 2) {
+ 		fp = fopen(fn, "wb");
+ 		if (!fp) {
+ 			php3_error(E_WARNING, "ImagePng: unable to open %s for writing", fn);
+ 			RETURN_FALSE;
+ 		}
+ 		gdImagePng (im,fp);
+ 		fflush(fp);
+ 		fclose(fp);
+ 	}
+ 	else {
+ 		int   b;
+ 		FILE *tmp;
+ 		char  buf[4096];
+ 
+ 		tmp = tmpfile();
+ 		if (tmp == NULL) {
+ 			php3_error(E_WARNING, "Unable to open temporary file");
+ 			RETURN_FALSE;
+ 		}
+ 
+ 		output = php3_header();
+ 
+ 		if (output) {
+ 			gdImagePng (im, tmp);
  			fseek(tmp, 0, SEEK_SET);
  #if APACHE && defined(CHARSET_EBCDIC)
  			/* This is a binary file already: avoid EBCDIC->ASCII conversion */
diff -rNc php-3.0.12/functions/php3_gd.h php-3.0.12-png/functions/php3_gd.h
*** php-3.0.12/functions/php3_gd.h	Mon Jul 12 19:34:15 1999
--- php-3.0.12-png/functions/php3_gd.h	Wed Aug  4 13:03:54 1999
***************
*** 72,77 ****
--- 72,78 ----
  extern void php3_imagecopyresized(INTERNAL_FUNCTION_PARAMETERS);
  extern void php3_imagecreate(INTERNAL_FUNCTION_PARAMETERS);
  extern void php3_imagecreatefromgif (INTERNAL_FUNCTION_PARAMETERS);
+ extern void php3_imagecreatefrompng (INTERNAL_FUNCTION_PARAMETERS);
  extern void php3_imagedestroy(INTERNAL_FUNCTION_PARAMETERS);
  extern void php3_imagefill(INTERNAL_FUNCTION_PARAMETERS);
  extern void php3_imagefilledpolygon(INTERNAL_FUNCTION_PARAMETERS);
***************
*** 80,85 ****
--- 81,87 ----
  extern void php3_imagefontwidth(INTERNAL_FUNCTION_PARAMETERS);
  extern void php3_imagefontheight(INTERNAL_FUNCTION_PARAMETERS);
  extern void php3_imagegif (INTERNAL_FUNCTION_PARAMETERS);
+ extern void php3_imagepng (INTERNAL_FUNCTION_PARAMETERS);
  extern void php3_imageinterlace(INTERNAL_FUNCTION_PARAMETERS);
  extern void php3_imageline(INTERNAL_FUNCTION_PARAMETERS);
  extern void php3_imageloadfont(INTERNAL_FUNCTION_PARAMETERS);