1. An image processing device comprising: a processor comprising hardware, the processor being configured to implement: a first image acquisition section that acquires a first image, the first image being a color image that includes a plurality of channels, and includes an object image including information within a wavelength band of white light; a second image acquisition section that acquires a second image, the second image being an image that includes an object image including information within a specific wavelength band, and differs from the plurality of channels included in the first image; a candidate attention area detection section that detects a candidate attention area based on a feature quantity of each pixel within the second image, the candidate attention area being a candidate for an attention area; a reliability calculation section that calculates reliability that indicates a likelihood that the candidate attention area detected by the candidate attention area detection section is the attention area; and a display mode setting section that performs a display mode setting process that sets a display mode of an output image corresponding to the reliability calculated by the reliability calculation section; the display mode setting section including a processing section that performs a processing process on the first image based on the reliability calculated by the reliability calculation section and the first image; the display mode setting section setting an area within the first image that corresponds to the attention area for which it has been determined that the reliability is high to be a corresponding attention area, and performing the processing process on the corresponding attention area; and the processing section performing a blending process on the first image and the second image based on the reliability as the processing process to set the display mode of the output image; wherein: the processing section includes an area selection section that selects the candidate attention area detected by the candidate attention area detection section as the attention area based on the reliability, and selects a corresponding attention area within the first image that corresponds to the selected attention area; and the processing section performs the blending process on the first image and the second image within the corresponding attention area; and wherein: the processing section includes an attention information setting section that sets attention information that indicates a degree of attention corresponding to the candidate attention area detected by the candidate attention area detection section, and a blending ratio setting section that sets a blending ratio of a pixel value of each pixel included in the candidate attention area within the second image and a pixel value of each pixel included in the corresponding attention area within the first image, corresponding to the degree of attention indicated by the attention information, and the processing section performs the blending process that blends the pixel value of each pixel included in the candidate attention area within the second image with the pixel value of each pixel included in the corresponding attention area within the first image according to the blending ratio set by the blending ratio setting section.