Twitter Inc‘s image-cropping AI contains a problematic bias toward cropping out Black people from the photos, the company said in new research on Wednesday, adding that “how to crop a picture is a decision best made by people.” The study by three of its machine learning researchers was organized after user criticism about image previews in posts excluding Black people’s faces. It found an 8 per cent difference from demographic parity in favor of women and a 4 per cent favor toward white peoples. The paper cited several possible reasons, including issues with image backgrounds and eye color.

“Machine learning-based cropping is basically wrong because it removes user agency and restricts user’s expression of their own identity and values, instead of impressing a normative look about which part of the image is considered the most interesting,” the researchers wrote. To fix the issue, Twitter recently started showing standard aspect ratio photos in full without any crop on its mobile apps and is trying to expand that effort.

The researchers also checked out if crops favored women’s bodies overheads, reflecting what is known as the “male gaze,” but found that does not appear to be the case. The findings are another example of the different impacts of artificial intelligence systems including demographic biases identified in facial recognition and text analysis, the paper said. Work by researchers at Microsoft Corp and the Massachusetts Institute of Technology in 2018 and a U.S. government study found that facial analysis systems misidentify people of color more often than white people.