Fix file ending

Author: jspricke

modules/aruco/tutorials/aruco_board_detection/aruco_board_detection.markdown

@@ -156,7 +156,7 @@ In this case the margin is 10.
 
 The output image will be something like this:
 
-![](images/board.jpg)
+![](images/board.png)
 
 A full working example of board creation is included in the `create_board.cpp` inside the `modules/aruco/samples/`.
 

modules/aruco/tutorials/aruco_board_detection/images/board.jpg renamed to modules/aruco/tutorials/aruco_board_detection/images/board.png

@@ -88,7 +88,7 @@ In this case the margin is 10.
 
 The output image will be something like this:
 
-![](images/charucoboard.jpg)
+![](images/charucoboard.png)
 
 A full working example is included in the `create_board_charuco.cpp` inside the `modules/aruco/samples/`.
 

modules/aruco/tutorials/charuco_detection/charuco_detection.markdown

@@ -30,7 +30,7 @@ values of the two squares with the picker tool.
 
 In this image I've cropped a little piece of the A and B squares and I've put them side-by-side.
 It should be quite evident they have the same luminance.
-![Adelson checkerboard proof](images/checkershadow_illusion4med_proof.jpg)
+![Adelson checkerboard proof](images/checkershadow_illusion4med_proof.png)
 
 It's worth to know that this illusion works because the checkerboard image, as you may see it
 on your laptop, casts on your retina with dimensions that cause the retina local adaptation to take
@@ -184,4 +184,4 @@ opportunity of writing this tutorial, and for reviewing it.
 
 **Edward Adelson** - for allowing me to freely use his checkerboard image.
 
-**Antonio Cuni**  - for reviewing this tutorial and for writing the Python code.
+**Antonio Cuni**  - for reviewing this tutorial and for writing the Python code.