We organize all the raw data from our research into a single Excel file titled ‘Source Data’. This file includes raw data of Figs. 1–4, Supplementary Fig. 1, Supplementary Fig. 2, Supplementary Fig. 5, Supplementary Figs. 7–13 and Supplementary Fig. 15–19.

The dataset contains raw visual images, visualized tactile images along the X- and Z-axes and an Excel file that organize every sample and their correspondence in order. The tactile images are interpolated on the raw haptic signal to align with the visual images. Both the visual and tactile images have identical resolution of 620 X 410. The dataset consists of 687 records. Each record includes one visual image, two tactile images along the X and Z axes, and one defect segmentation image. Tactile image filenames ending with x and z denote X and Z components respectively.The samples in the dataset exhibit a wide range of colors and textures. Moreover, the dataset demonstrates the advantage of cross-modal data fusion. As a flexible material, leather may have defects on its surface and underside, which can be observed in the visual and tactile images, respectively. Combining visual and tactile images provides better information on the distribution of defects