What phrase describes a negative mental image one has of themselves compared to others?

The phrase that describes a negative mental image one has of themselves compared to others is "negative self-concept." This term encompasses how individuals perceive their own worth and abilities in relation to others, often leading to feelings of inadequacy or undesirability. When someone possesses a negative self-concept, they may focus on their perceived flaws and shortcomings, which can significantly affect their self-esteem, relationships, and overall mental health. It captures the essence of self-image and how it is colored by comparisons with others, making it the most accurate choice in this context.