A CoreImage developer specializes in utilizing Apple's Core Image framework to manipulate and analyze images for iOS applications. They apply filters, effects, and transformations to images, and create custom filters using the Core Image Kernel language. They handle tasks such as face detection, red-eye reduction, and color adjustments. They also work with other APIs for better image processing, like handling image metadata or integrating with Core ML for advanced image analysis. CoreImage developers need proficiency in Swift or Objective-C, and a solid understanding of image processing techniques to enhance the visual aspects of iOS applications.