skimage could be problematic

Hi,
You said that "A few images are in a weird format ". I found that skimage could be problematic to read images.
Skimage will treat some rgb images like grey scale images (idk why, but it happens). However, simply change to cv2, it works normally and correctly read rgb images.

Start by locating the image-reading entry point used during Open Images to COCO conversion and reproduce the reported behavior with RGB images. Compare the current skimage-based reading with cv2 using a representative image, then verify that RGB images are read correctly and the conversion still produces valid output.

Written by the indexing model from the issue text.