Mobile device, and image processing method for mobile device

1. An image processing method, suitable for a mobile device comprising a camera unit and a display unit, the image processing method comprising:

separating a foreground portion and a background portion of a first image sensed by the camera unit;

calculating a dimension of the foreground portion;

generating an adjustment level that is positively correlated with the dimension of the foreground portion;

applying an image effect at the adjustment level to the foreground portion or the background portion of the first image to generate a second image; and

displaying the second image by the display unit;

wherein the dimension of the foreground portion is one of a distance between two eyes, a size of a triangular area formed between two eyes and a nose, a second area of the foreground portion, and a percentage between the second area of the foreground portion and a first area of the first image.

2. The image processing method as claimed in claim 1 , wherein the image effect is a bokeh effect, the adjustment level is a bokeh level, the dimension of the foreground portion is positively correlated with the bokeh level so as to adjust a blur difference between the foreground portion and the background portion.

3. The image processing method as claimed in claim 2 , wherein the bokeh effect is applied to the background portion.

4. The image processing method as claimed in claim 2 , wherein the bokeh effect is applied to the foreground portion.

5. The image processing method as claimed in claim 2 , wherein the bokeh effect is applied to the foreground portion when the dimension of the foreground portion is lower than a threshold, and the bokeh effect is applied to the background portion when the dimension of the background portion is larger than the threshold.

6. The image processing method as claimed in claim 1 , wherein the operation of calculating the dimension of the foreground portion comprises:

identifying a face in the foreground portion;

locating two eyes on the face; and

calculating the distance between the two eyes, wherein the distance is regarded as the dimension of the foreground portion.

7. The image processing method as claimed in claim 1 , wherein the operation of calculating the dimension of the foreground portion comprises:

obtaining the first area of the first image;

measuring the second area of the foreground portion; and

calculating the percentage of the second area relative to the first area, wherein the percentage is regarded as the dimension of the foreground portion.

8. The image processing method as claimed in claim 1 , wherein the adjustment level is linearly or exponentially correlated with the dimension of the foreground portion.

9. The image processing method as claimed in claim 1 , wherein the image effect is a brightness effect, the adjustment level is a brightness level, the dimension of the foreground portion is positively correlated with the brightness level so as to adjust a brightness difference between the foreground portion and the background portion.

10. The image processing method as claimed in claim 1 , wherein the image effect is a saturation effect, the adjustment level is a saturation level, the dimension of the foreground portion is positively correlated with the saturation level so as to adjust a saturation difference between the foreground portion and the background portion.

11. A mobile device comprising:

a camera unit configured to sense a first image;

a display unit;

a processing unit coupled to the camera unit and the display unit, the processing unit configured to:

separate a foreground portion and a background portion of the first image;

calculate a dimension of the foreground portion;

generate an adjustment level that is positively correlated with the dimension of the foreground portion;

apply an image effect at the adjustment level to the foreground portion or the background portion of the first image to generate a second image; and

transmit the second image to the display unit to display the second image,

wherein the dimension of the foreground portion is one of a distance between two eyes, a size of a triangular area formed between two eyes and a nose, a second area of the foreground portion, and a percentage between the second area of the foreground portion and a first area of the first image.

12. The mobile device as claimed in claim 11 , wherein

the image effect is a bokeh effect, the adjustment level is a bokeh level, the dimension of the foreground portion is positively correlated with the bokeh level so as to adjust a blur difference between the foreground portion and the background portion.

13. The mobile device as claimed in claim 12 , wherein the bokeh effect is applied to the background portion.

14. The mobile device as claimed in claim 12 , wherein the bokeh effect is applied to the foreground portion.

15. The mobile device as claimed in claim 12 , wherein the bokeh effect is applied to the foreground portion when the dimension of the foreground portion is lower than a threshold, and the bokeh effect is applied to the background portion when the dimension of the background portion is larger than the threshold.

16. The mobile device as claimed in claim 11 , wherein the processing unit is further configured to:

identify a face in the foreground portion;

locate two eyes on the face; and

calculate the distance between the two eyes, wherein the distance is regarded as the dimension of the foreground portion.

17. The mobile device as claimed in claim 11 , wherein the processing unit is further configured to:

obtain the first area of the first image;

measure the second area of the foreground portion; and

calculate the percentage of the second area relative to the first area, wherein the percentage is regarded as the dimension of the foreground portion.

18. The mobile device as claimed in claim 11 , wherein the adjustment level is linearly or exponentially correlated with the dimension of foreground portion.

19. The mobile device as claimed in claim 11 , wherein the image effect is a brightness effect, the adjustment level is a brightness level, the dimension of the foreground portion is positively correlated with the brightness level so as to adjust a brightness difference between the foreground portion and the background portion.

20. The mobile device as claimed in claim 11 , wherein the image effect is a saturation effect, the adjustment level is a saturation level, the dimension of the foreground portion is positively correlated with the saturation level so as to adjust a saturation difference between the foreground portion and the background portion.