diff --git a/sw/airborne/modules/computer_vision/cv_blob_locator.c b/sw/airborne/modules/computer_vision/cv_blob_locator.c
index 4b1ad49d45..03e65456d8 100644
--- a/sw/airborne/modules/computer_vision/cv_blob_locator.c
+++ b/sw/airborne/modules/computer_vision/cv_blob_locator.c
@@ -53,11 +53,11 @@ volatile bool_t marker_enabled = FALSE;
 volatile bool_t window_enabled = FALSE;
 
 // Computer vision thread
-bool_t cv_marker_func(struct image_t *img);
-bool_t cv_marker_func(struct image_t *img) {
+struct image_t* cv_marker_func(struct image_t *img);
+struct image_t* cv_marker_func(struct image_t *img) {
 
   if (!marker_enabled)
-    return FALSE;
+    return NULL;
 
   struct marker_deviation_t m = marker(img, marker_size);
 
@@ -66,18 +66,18 @@ bool_t cv_marker_func(struct image_t *img) {
   temp += m.y;
   blob_locator = temp;
 
-  return FALSE;
+  return NULL;
 }
 
 #define Img(X,Y)(((uint8_t*)img->buf)[(Y)*img->w*2+(X)*2])
 
 
 // Computer vision thread
-bool_t cv_window_func(struct image_t *img);
-bool_t cv_window_func(struct image_t *img) {
+struct image_t* cv_window_func(struct image_t *img);
+struct image_t* cv_window_func(struct image_t *img) {
 
   if (!window_enabled)
-    return FALSE;
+    return NULL;
 
 
   uint16_t coordinate[2] = {0,0};
@@ -114,15 +114,15 @@ bool_t cv_window_func(struct image_t *img) {
 
   }
 
-  return FALSE;
+  return NULL;
 }
 
 
-bool_t cv_blob_locator_func(struct image_t *img);
-bool_t cv_blob_locator_func(struct image_t *img) {
+struct image_t* cv_blob_locator_func(struct image_t *img);
+struct image_t* cv_blob_locator_func(struct image_t *img) {
 
   if (!blob_enabled)
-    return 0;
+    return NULL;
 
 
   // Color Filter
@@ -209,7 +209,7 @@ bool_t cv_blob_locator_func(struct image_t *img) {
 
   image_free(&dst);
 
-  return 0; // No new image is available for follow up modules
+  return NULL; // No new image is available for follow up modules
 }
 
 #include "modules/computer_vision/cv_georeference.h"
diff --git a/sw/airborne/modules/computer_vision/detect_window.c b/sw/airborne/modules/computer_vision/detect_window.c
index 0101849d63..fb76dc83ce 100644
--- a/sw/airborne/modules/computer_vision/detect_window.c
+++ b/sw/airborne/modules/computer_vision/detect_window.c
@@ -31,12 +31,12 @@
 #include "detect_window.h"
 #include <stdio.h>
 
-extern void detect_window_init(void)
+void detect_window_init(void)
 {
   cv_add(detect_window);
 }
 
-extern bool_t detect_window(struct image_t *img)
+struct image_t* detect_window(struct image_t *img)
 {
 
   uint16_t coordinate[2];
@@ -53,7 +53,7 @@ extern bool_t detect_window(struct image_t *img)
   printf("Response = %d\n", response);
 
   image_free(&gray);
-  return 0; // No new image was created
+  return NULL; // No new image was created
 }
 
 
diff --git a/sw/airborne/modules/computer_vision/detect_window.h b/sw/airborne/modules/computer_vision/detect_window.h
index 47f6d03d14..5cfea9f661 100644
--- a/sw/airborne/modules/computer_vision/detect_window.h
+++ b/sw/airborne/modules/computer_vision/detect_window.h
@@ -35,7 +35,7 @@
 #include "inttypes.h"
 
 extern void detect_window_init(void);
-extern bool_t detect_window(struct image_t *img);
+extern struct image_t* detect_window(struct image_t *img);
 
 uint16_t detect_window_sizes(uint8_t *in, uint32_t image_width, uint32_t image_height, uint16_t *coordinate,
                              uint32_t *integral_image, uint8_t MODE);
diff --git a/sw/airborne/modules/computer_vision/qrcode/qr_code.c b/sw/airborne/modules/computer_vision/qrcode/qr_code.c
index 41917da9c3..9b19702291 100644
--- a/sw/airborne/modules/computer_vision/qrcode/qr_code.c
+++ b/sw/airborne/modules/computer_vision/qrcode/qr_code.c
@@ -99,5 +99,5 @@ struct image_t* qrscan(struct image_t *img)
   zbar_image_destroy(image);
   //zbar_image_scanner_destroy(scanner);
 
-  return 0; // QRCode is not returning a new image.
+  return NULL; // QRCode is not returning a new image.
 }
diff --git a/sw/airborne/modules/computer_vision/viewvideo.c b/sw/airborne/modules/computer_vision/viewvideo.c
index bf518e622c..4f5283f66e 100644
--- a/sw/airborne/modules/computer_vision/viewvideo.c
+++ b/sw/airborne/modules/computer_vision/viewvideo.c
@@ -189,7 +189,7 @@ struct image_t* viewvideo_function(struct image_t *img)
   // Free all buffers
   image_free(&img_jpeg);
   image_free(&img_small);
-  return 0; // No new images were created
+  return NULL; // No new images were created
 }
 
 /**