diff --git a/cronjob/chart/image_file/image_data.c b/cronjob/chart/image_file/image_data.c
index 2306ab4..6bf9b8e 100644
--- a/cronjob/chart/image_file/image_data.c
+++ b/cronjob/chart/image_file/image_data.c
@@ -24,11 +24,32 @@ static PGresult *pg_check_exec(PGconn *, char *);
 static char *get_type_table_by_id(PGconn *, int );
 
 
+/* Skaliert die X-Koordinaten der Punkte im angegebenem Bereich
+ * ausführliche Beschreibung im header-file */
+int scale_y_coords(pix_list_ptr ptr, int c_height, int max_label, int min_label){
+  int range            = (max_label - min_label + 1) * 10;				/* Anzahl von 0,1-Schritten */
+  double pix_per_scale = ((double)c_height) / ((double)range); 				/* Pixel pro 0,1 */
+  pix_list_ptr temp    = ptr;
+  int zero_line        = floor( ((double)max_label) * pix_per_scale);			/* Nullinie */
+  
+  DEBUGOUT1("\nBerechne y-Koordinaten:\n");
 
+  for (; temp; temp = temp->next){
+    temp->y_pix_coord = floor( ( ((double)temp->value_sum) / ((double)temp->value_count) ) * pix_per_scale);
+    DEBUGOUT3("  neue y-Koordinate: %d bei x: %d\n",temp->y_pix_coord, temp->x_pix_coord);
+  }
+
+  DEBUGOUT2(" Nullinie bei: %d\n", zero_line);
+
+  return zero_line;
+}
+
+/* Maximaler wert */
 pix_list_ptr get_max(){
   return min;
 }
 
+/* Minimaler Wert */
 pix_list_ptr get_min(){
   return max;
 }
@@ -73,8 +94,15 @@ pix_list_ptr get_pix_list(int c_width){
     pix_coord = floor( ((double)time_temp) * seconds_per_pix) ;
     temp_ptr = add_pix_value(temp_ptr, pix_coord, atoi( PQgetvalue(res, i, val_field) ) );
 
-    if (list_ptr == NULL)
+    if (list_ptr == NULL){
       list_ptr = temp_ptr;
+      
+      /* Globale Variablen neu initialisieren um 
+       * mehtete Bilder in einem Thread bauen zu
+       * können */
+      min = temp_ptr;
+      max = temp_ptr;
+    }
 
     /* Min / Max ermitteln */
     if (min != NULL){
@@ -112,6 +140,7 @@ static pix_list_ptr add_pix_value(pix_list_ptr ptr, int coord, int value){
     ptr  		= malloc(sizeof(pix_list_t));
     ptr->next 		= NULL;
     ptr->x_pix_coord 	= 0;
+    ptr->y_pix_coord 	= 0;
     ptr->value_count    = 0;
     ptr->value_sum	= 0;
     DEBUGOUT1("  Erstes Element generiert...\n");
@@ -126,6 +155,7 @@ static pix_list_ptr add_pix_value(pix_list_ptr ptr, int coord, int value){
     ptr->next 		= malloc(sizeof(pix_list_t));
     ptr 		= ptr->next;
     ptr->x_pix_coord	= coord;
+    ptr->y_pix_coord	= coord;
     ptr->value_sum 	= value;
     ptr->value_count 	= 1;
     ptr->next           = NULL;
diff --git a/cronjob/chart/image_file/image_data.h b/cronjob/chart/image_file/image_data.h
index b6c5ede..a493f48 100644
--- a/cronjob/chart/image_file/image_data.h
+++ b/cronjob/chart/image_file/image_data.h
@@ -5,6 +5,7 @@ typedef struct pix_list *pix_list_ptr;
 typedef struct pix_list {
   pix_list_ptr 	next;
   int 		x_pix_coord;
+  int 		y_pix_coord;
   int 		value_count;
   int 		value_sum;
 } pix_list_t;
@@ -19,3 +20,12 @@ pix_list_ptr get_pix_list(int );
 pix_list_ptr get_min();
 
 pix_list_ptr get_max();
+
+/* Skaliert die X-Koordinaten der Punkte im angegebenem Bereich
+ * 1. Argument: die Pix-Liste die skaliert werden soll
+ * 2. Argument: die anzahl der Pixel in y-Richtung
+ * 3. Argument: max. Wert
+ * 4. Argument: min. Wert
+ * Rueckgabe: Position der 0-Linie von oben aus
+ */
+int scale_y_coords(pix_list_ptr , int , int , int );
diff --git a/cronjob/chart/image_file/image_draw.c b/cronjob/chart/image_file/image_draw.c
index 81f658f..04b413a 100644
--- a/cronjob/chart/image_file/image_draw.c
+++ b/cronjob/chart/image_file/image_draw.c
@@ -9,13 +9,13 @@ typedef int color;
 
 
 static gdImagePtr create_image();
-static void draw_image();
+static gdImagePtr draw_image(gdImagePtr);
 static void write_image_png(gdImagePtr, FILE *);
 
 
 int draw_to_file(FILE *fd){
   gdImagePtr img = create_image();
-  draw_image();
+  draw_image(img);
   write_image_png(img, fd);
 }
 
@@ -33,9 +33,9 @@ static gdImagePtr create_image(){
   return new_img;
 }
 
-static void draw_image(){
+static gdImagePtr draw_image(gdImagePtr img){
   pix_list_ptr pix_list = get_pix_list(300);
-
+  scale_y_coords(pix_list, 100, 40, -10);  
 }
 
 static void write_image_png(gdImagePtr img, FILE *fd){
@@ -43,3 +43,5 @@ static void write_image_png(gdImagePtr img, FILE *fd){
   gdImageSaveAlpha(img, 1);
   gdImagePng(img, fd);
 }
+
+