Disclosed are methods, systems, and apparatus for load-balancing image-processing jobs based on the number of pixels in the images and/or the nature of the processing that is requested on those pixels. For example, a set of machines may run software to provide various types of image processing services, such as format conversion, recompression, resizing, cropping, among others. These are referred to as image servers. In accordance with the teachings hereof, the load on each image server can be calculated based on the number of pixels in the images that are waiting to be processed in the image server's processing queue, adjusted by the type of processing that is requested on each image. The adjustment typically reflects and adjusts for the relative time needed to perform various types of processing. Load scores can be further adjusted based on the processing capabilities of each image server, in some embodiments.