1. Automating the Polarizing Filter
Help taking great pictures easier

2. Motivation Everything else in the camera is already automated,
Why not make life even simpler?

3. What is a polarizing filter?
only transfers light in a specific plane
reduces or eliminates glare and reflections
improves both contrast and color saturation
glare cannot be reduced after taking the picture

4. examples

5. Objective
We want the camera to select automatically between pictures of different polarization angles every time we push the button, so even the novice photographer will take expert photos

6. The Algorithm Picture alignment. Initial guess. Gaussian smoothing.
Differentiation.
Modified hysteresis.
Scoring.

7. alignment
Take a few pictures of the same object with different rotations of the filter
Align them using pixel shifting™

8. Initial guess
Using the images’ entropy as an ad-hoc basis of comparison, choose two extremes (min and max)

9. Gaussian smoothing
Use the smoothing technique to diminish small local differences between images

10. Differentiation
By subtracting the two images of the initial guess (after they have been smoothed) regions of big difference between images are emphasized.

11. Hysteresis
Use a hysteresis algorithm to determine regions of inter-image change

12. Scoring
To select the optimal image according to the user’s specification, score the image’s characteristics

13. What else?
We still need to determine the two hysteresis thresholds, which can be done automatically with a bit more research

14. no questions?