Method and apparatus for processing thermal image
Disclosed herein is a method and apparatus for processing a thermal image. The method includes: performing histogram stretching on thermal image data of the thermal image; and adjusting a histogram stretching scale for thermal image data of a next frame using histogram data of the thermal image data on which the histogram stretching is performed. As a result, it is possible to mitigate that an image becomes less recognizable as thermal image data is deteriorated or saturated.
1. A method for processing a thermal image, the method comprising:
performing histogram stretching on thermal image data of a current frame to obtain stretched thermal image data; and
adjusting a histogram stretching scale for thermal image data of a next frame based on a comparison between histogram data of the stretched thermal image data of the current frame and a plurality of threshold values,
wherein the plurality of threshold values comprise at least one from among a deterioration threshold value and a saturation threshold value,
wherein the adjusting the histogram stretching scale comprises at least one from among increasing the histogram stretching scale based on determining that the stretched thermal image data is deteriorated, and decreasing the histogram stretching scale based on determining that it the stretched thermal image data is saturated.
2. The method of claim 1 , wherein the adjusting the histogram stretching scale comprises:
determining whether the stretched thermal image data is deteriorated or saturated using the histogram data of the stretched thermal image data; and
adjusting the histogram stretching scale in response to determining that the thermal image data is deteriorated or saturated.
3. The method of claim 2 , wherein the determining whether the stretched thermal image data is deteriorated or saturated comprises:
comparing a minimum value of the histogram data of the stretched thermal image data with at least one threshold value.
4. The method for claim 3 , wherein the determining whether the stretched thermal image data is deteriorated or saturated comprises:
determining that the stretched thermal image data is deteriorated if the minimum value is below the deterioration threshold value; and
determining that the stretched thermal image data is saturated if the minimum value is above the saturation threshold value.
5. The method of claim 4 , wherein the adjusting the histogram stretching scale comprises:
increasing the histogram stretching scale by increasing the deterioration threshold value in response to determining that the stretched thermal image data is deteriorated; and
decreasing the histogram stretching scale by decreasing the saturation threshold value in response to determining that the stretched thermal image data is saturated.
6. The method of claim 1 , wherein the adjusting the histogram stretching scale is performed at every predetermined number of frames or at a predetermined interval.
7. The method of claim 6 , wherein the predetermined number of frames or the predetermined interval is set to be adjusted based on a temperature change of an area of the current frame.
8. The method of claim 1 , wherein the adjusting the histogram stretching scale comprises adjusting the histogram stretching scale with a predetermined scale.
9. The method of claim 1 , wherein the adjusting the histogram stretching scale is performed differently according to a temperature change of an area of the current frame.
10. An apparatus for processing a thermal image, the apparatus comprising:
at least one processor configured to:
perform histogram stretching on thermal image data of a current frame to obtain stretched thermal image data; and
adjust a histogram stretching scale for thermal image data of a next frame based on a comparison between histogram data of the stretched thermal image data of the current frame and a plurality of threshold values,
wherein the plurality of threshold values comprise at least one from among a deterioration threshold value and a saturation threshold value, and
wherein the at least one processor is further configured to increase the histogram stretching scale in response to determining that the stretched thermal image data is deteriorated, and decrease the histogram stretching scale in response to determining that the stretched thermal image data is saturated.
11. The apparatus of claim 10 , wherein the at least one processor is further configured to determine whether the stretched thermal image data is deteriorated or saturated using the histogram data of the thermal image data, and adjusts the histogram stretching scale in response to determining that the thermal image data is deteriorated or saturated.
12. The apparatus of claim 11 , wherein the at least one processor is further configured to determine whether the stretched thermal image data is deteriorated or saturated by comparing a minimum value of the histogram data of the stretched thermal image data with at least one threshold value.
13. The apparatus of claim 12 , wherein the at least one processor is further configured to determine that the stretched thermal image data is deteriorated if the minimum value is below the deterioration threshold value, determines that the stretched thermal image data is saturated if the minimum value is above the saturation threshold value.
14. The apparatus of claim 13 , wherein the at least one processor is further configured to increase the histogram stretching scale by increasing the deterioration threshold value in response to determining that the stretched thermal image data is deteriorated, and decrease the histogram stretching scale by decreasing the saturation threshold value in response to determining that the stretched thermal image data is saturated.
15. The apparatus of claim 10 , wherein the at least one processor is further configured to determine whether the stretched thermal image data is deteriorated or saturated at every predetermined number of frames or at a predetermined interval.
16. The apparatus of claim 15 , wherein the predetermined number of frames or the predetermined interval is set to be adjusted based on a temperature change of an area of the current frame.
17. The apparatus of claim 10 , wherein the at least one processor is further configured to adjust the histogram stretching scale with a predetermined scale.
18. An apparatus for processing a thermal image, the apparatus comprising:
a receiver configured to receive thermal image data of a current frame;
at least one processor configured to perform histogram stretching on the thermal image data of the current frame to obtain stretched thermal image data; and
a transmitter configured to output an image on which the histogram stretching has been performed,
wherein the at least one processor is further configured to adjust a histogram stretching scale for thermal image data of a next frame based on a comparison between histogram data of the stretched thermal image data of the current frame and a plurality of threshold values,
wherein the plurality of threshold values comprise at least one from among a deterioration threshold value and a saturation threshold value, and
wherein the at least one processor is further configured to increase the histogram stretching scale in response to determining that the stretched thermal image data is deteriorated, and decreases the histogram stretching scale in response to determining that the stretched thermal image data is saturated.