Endoscope system, processor device, and method for operating endoscope system

1. An endoscope system comprising a processor configured to: acquire first image and a second image, the first image being obtained by imaging an observation target by using first illumination light, the second image being obtained by imaging the observation target by using second illumination light that is different from the first illumination light at a different timing from the first image; detect a halation region from at least one of the first image or the second image; perform calculation by using the first image and the second image and that generates a calculated image; generate a display image in which a tone reflects the calculated image; and change the tone of the halation region in the display image, wherein, when generating the display image, the processor is further configured to add a weight to the calculated image and assign the calculated image to a chroma channel, and wherein the processor is further configured to adjust the threshold by using the weight of the calculated image.

2. The endoscope system according to claim 1 ,

wherein the processor is further configured to correct at least a pixel value of the calculated image to change the tone of the display image.

3. The endoscope system according to claim 2 ,

wherein the processor is further configured to change at least one of a saturation, a hue, or a brightness.

4. The endoscope system according to claim 3 ,

wherein the processor is further configured to suppress the saturation of the halation region in the display image.

5. The endoscope system according to claim 4 ,

wherein the processor is further configured to make the halation region in the display image have an achromatic color.

6. The endoscope system according to claim 4 ,

wherein the processor is further configured to suppress a degree of the pixel value of the calculated image to a threshold.

7. The endoscope system according to claim 1 ,

wherein the processor is further configured to change at least one of a saturation, a hue, or a brightness.

8. The endoscope system according to claim 7 ,

wherein the processor is further configured to suppress the saturation of the halation region in the display image.

9. The endoscope system according to claim 8 ,

wherein the processor is further configured to make the halation region in the display image have an achromatic color.

10. The endoscope system according to claim 8 ,

wherein the processor is further configured to suppress a degree of the pixel value of the calculated image to a threshold.

11. The endoscope system according to claim 1 , wherein the processor is further configured to:

assign any one of the first image and the second image to a luminance channel and assigns the calculated image to the chroma channel to generate the display image,

detect the halation region from the one of the first image and the second image assigned to the luminance channel, and

change at least a tone of the halation region in the display image, the halation region being detected from the one of the first image and the second image assigned to the luminance channel.

12. The endoscope system according to claim 1 ,

wherein the processor is further configured to change the tone of the halation region in the first image and the tone of the halation region in the second image.

13. The endoscope system according to claim 1 ,

wherein the processor is further configured to generate, as the calculated image, a difference image between the first image and the second image.

14. The endoscope system according to claim 1 ,

wherein the processor is further configured to detect the halation region by using a histogram representing an appearance frequency of the pixel value.

15. The endoscope system according to claim 14 ,

wherein the processor is further configured to detect the halation region in a specific pixel-value range in a direction from a maximum pixel value to a smaller pixel value.

16. The endoscope system according to claim 15 ,

wherein the processor is further configured to detect a peak of a valley of the histogram in the specific pixel-value range and detects, as the halation region, a set of pixels having pixel values larger than or equal to a pixel value at the peak of the valley and smaller than or equal to the maximum pixel value.

17. The endoscope system according to claim 1 , wherein the processor is further configured to:

smooth the calculated image to be used by the display-image generating unit to generate the display image.

18. A method for operating an endoscope system according to claim 1 , the method comprising: acquiring a first image and a second image, the first image being obtained by imaging an observation target by using first illumination light, the second image being obtained by imaging the observation target by using second illumination light that is different from the first illumination light at a different timing from the first image; detecting a halation region from at least one of the first image or the second image; calculating by using the first image and the second image to generate a calculated image; generating a display image in which a tone reflects the calculated image; and changing the tone of the halation region in the display image, wherein changing the tone of the halation region in the display image comprising changing the tone of the halation region in the first image and the tone of the halation region in the second image.