Method and apparatus for visible light communication with image processing

1. An apparatus for performing visible light communication, comprising:

an image input unit configured to input image data representing an image photographed of a light source of visible light carrying transmission data, the transmission data including a preamble and a data bit train;

a calculation unit configured to calculate from the image data, a luminance value at a designated position in a region of interest of the image data;

a change-threshold calculation unit configured to (i) calculate a maximum luminance and a minimum luminance from the luminance value and (ii) calculate a threshold value for detecting a blinking frequency of the light source corresponding to an on-off frequency of pulse signals of the transmission data;

a preamble detection unit configured to detect the preamble from the image data based on the threshold value of the luminance value;

a bit train detection unit configured to detect the data bit train, from the image data, based on the threshold value and the preamble; and

a reception unit configured to reproduce the transmission data based on the data bit train.

2. The apparatus of claim 1 , wherein the image input unit is configured to receive image data for each frame, one after another and the calculation unit is configured to calculate the luminance value from the image data for each frame.

3. The apparatus of claim 1 , wherein the preamble detection unit is configured to detect the preamble if the on-time and off-time of the pulse signals satisfy prescribed conditions.

4. The apparatus of claim 1 , further comprising an extraction unit configured to extract the region of interest having a luminous dot at which the luminance value of the image data greatly changes,

wherein the image input unit is configured to receive the image data associated with the region of interest.

5. The apparatus of claim 4 , further comprising a luminous-dot position calculation unit configured to calculate a position of the luminous dot for the image data associated with the region of interest,

wherein the calculation unit is configured to calculate the luminance value at the position of the luminous dot.

6. The apparatus of claim 1 , further comprising a correction unit configured to correct bit displacement in a data bit train detected by the bit train detection unit, on the basis of a change in a frame rate of the image data.

7. The apparatus of claim 1 , wherein the image input unit includes a camera incorporating an image sensor.

8. The apparatus of claim 1 , wherein the reception unit is configured to convert the data bit train detected by the bit train detection unit to character train data.

9. A method of receiving data from visible light in visible light communication, the method comprising:

inputting image data representing an image photographed of a light source of visible light carrying transmission data, the transmission data including a preamble and a data bit train;

calculating, from the image data, a luminance value at a designated position in a region of interest of the image data;

calculating (i) a maximum luminance and a minimum luminance from the luminance value and (ii) a threshold value for detecting a blinking frequency of the light source corresponding to an on-off frequency of pulse signals of the transmission data;

detecting the preamble from the image data based on the threshold value of the luminance value;

detecting the data bit train, from the image data, based on the threshold value and the preamble; and

reproducing the transmission data based on the data bit train.