*A.2. The Experiments of the Values in Table 2*

Figure A1 illustrates the examples using different settings for the constant value *C*. It is noteworthy that *C* in Table 2 aims to correct the difference from the " *ρ* ≈ *ρ*" in Equation (4). According to the assumption in Section 2.2.1, this difference is small but sensitive to rock property. The goal of *C* is to optimize the visual comfort mentioned in Section 3.1. Therefore, *C* is affected by two settings, range and scale.

The range of the pixel value is between 0 and 256. (i) In Table 2, the range of *C* is set from 0 to 50. Thus, the maximum adjustment is less than 20% of the pixel value. Figure A1b shows a synthetic example using Table 2, and the white pixels in Figure A1a highlight the rocks. Figure A1a,b depict that Table 2 is a visually comfortable setting. Figure A1c,d respectively increase the range of *C* by three times and five times, and the embedded rock samples are very unreal to the background. Figure A1e reduces the range of *C* to about half of Figure A1b. The inserted rock is too bright compared to the background. Therefore, the range setting of *C* in Table 2 is in a reasonable range. (ii) *C* in Table 2 is divided into 11 scales according to the corresponding conditions (*imgmean*). A higher img\_mean corresponds to a higher *C*. Figure A1f doubles the scale-setting to 21 scales, but there is no significant change compared to Figure A1b. Therefore, the classification method in Table 2 is also reasonable.

**Figure A1.** The visualized results of the experiments for the constant *C* in Table 2. (**a**) refers to the synthetic annotation, while (**b**–**f**) corresponds to the synthetic images through different settings of *C*. (**b**) applies the same setting as Table 2. (**c**) keeps the grade setting but increases the range of the *C*, the maximum *C* is set to 250. (**d**) refers to the results of only increasing maximum *C* to 150. (**e**) refers to the results of decreasing maximum *C* to 20. (**f**) keeps the maximum *C* as the same as (**b**), while the grade setting applies 21 grades.

**Figure A2.** Some examples from the synthetic dataset. "Synthetic image" and "annotation" refer to the synthetic images and corresponding annotations, respectively. Annotations use white and black pixels to represent the rock and background pixels.
