1. A computer system with a processor for detecting similar images, comprising: a generate code component that generates a code for an image, the code having elements whose values are derived from features of the image, the elements having varying levels of significance such that similar images have similar codes with the most significant elements having the same values, the code being generated by creating a feature vector of a certain dimension that represents the image, reduces the dimension of the feature vector, and creates a code from the reduced feature vector with the reduced dimension; an image table that groups images based on having the same values for the most significant elements; and a detection component that uses the generate code component to generate a code for a target image, that identifies the group of images with the same values for the most significant elements as the generated code, and that identifies, from the images within the identified group, images whose codes vary less than a threshold amount from the code of the target image.