Information communication method for obtaining information using bright line image

1. An apparatus, comprising:

a processor; and

a recording medium having a program, the program causing the processor to execute operations including:

a normal mode and a visible light communication mode, wherein the normal mode and the visible light communication mode are switchable,

in the normal mode, obtaining first image data by image capture with a first exposure time by sequentially starting exposure for a plurality of exposure lines in an image sensor each at a different time and each of the plurality of exposure lines partially overlaps in exposure time an adjacent exposure line,

in the visible light communication mode,

(i) setting a second exposure time of the image sensor so that, in an image obtained by capturing a subject by the image sensor, a plurality of bright lines corresponding to the plurality of exposure lines included in the image sensor appear according to a change in luminance of the subject,

(ii) obtaining a bright line image including the plurality of bright lines, by capturing the subject changing in luminance by the image sensor with the set second exposure time by sequentially starting exposure for the plurality of exposure lines in the image sensor each at the different time and each of the plurality of exposure lines partially overlaps in exposure time the adjacent exposure line, and

(iii) obtaining information by demodulating data specified by a pattern of the plurality of bright lines included in the obtained bright line image,

wherein, a gap time between a exposure starting time of each of the plurality of exposure lines and a exposure starting time of the adjacent exposure line is longer than a transition time of the change in luminance of the subject, the transition time indicating a time for change in luminance of the subject from a high brightness to a low brightness.

2. The apparatus according to claim 1 ,

wherein the second exposure time is shorter than the first exposure time and shorter than 1/2000 second.

3. A method, comprising:

a normal mode and a visible light communication mode, wherein the normal mode and the visible light communication mode are switchable,

in the normal mode, obtaining first image data by image capture with a first exposure time by sequentially starting exposure for a plurality of exposure lines in an image sensor each at a different time and each of the plurality of exposure lines partially overlaps in exposure time an adjacent exposure line,

in the visible light communication mode,

(i) setting a second exposure time of the image sensor so that, in an image obtained by capturing a subject by the image sensor, a plurality of bright lines corresponding to the plurality of exposure lines included in the image sensor appear according to a change in luminance of the subject,

(ii) obtaining a bright line image including the plurality of bright lines, by capturing the subject changing in luminance by the image sensor with the set second exposure time by sequentially starting exposure for the plurality of exposure lines in the image sensor each at the different time and each of the plurality of exposure lines partially overlaps in exposure time the adjacent exposure line, and

(iii) obtaining information by demodulating data specified by a pattern of the plurality of bright lines included in the obtained bright line image,

wherein, a gap time between a exposure starting time of each of the plurality of exposure lines and a exposure starting time of the adjacent exposure line is longer than a transition time of the change in luminance of the subject, the transition time indicating a time for change in luminance of the subject from a high brightness to a low brightness.

4. A non-transitory computer-readable recording medium having a program stored therein that when executed by a processor causes the processor to execute operations including:

a normal mode and a visible light communication mode, wherein the normal mode and the visible light communication mode are switchable,

in the normal mode, obtaining first image data by image capture with a first exposure time by sequentially starting exposure for a plurality of exposure lines in an image sensor each at a different time and each of the plurality of exposure lines partially overlaps in exposure time an adjacent exposure line,

in the visible light communication mode,

(i) setting a second exposure time of the image sensor so that, in an image obtained by capturing a subject by the image sensor, a plurality of bright lines corresponding to the plurality of exposure lines included in the image sensor appear according to a change in luminance of the subject,

(ii) obtaining a bright line image including the plurality of bright lines, by capturing the subject changing in luminance by the image sensor with the set second exposure time by sequentially starting exposure for the plurality of exposure lines in the image sensor each at the different time and each of the plurality of exposure lines partially overlaps in exposure time the adjacent exposure line, and

(iii) obtaining information by demodulating data specified by a pattern of the plurality of bright lines included in the obtained bright line image,

wherein, a gap time between a exposure starting time of each of the plurality of exposure lines and a exposure starting time of the adjacent exposure line is longer than a transition time of the change in luminance of the subject, the transition time indicating a time for change in luminance of the subject from a high brightness to a low brightness.