Prompt-Based Exemplar Super-Compression and Regeneration for
  Class-Incremental Learning
Ruxiao Duan Yaoyao Liu Jieneng Chen Adam Kortylewski Alan Yuille
Replay-based methods in class-incremental learning (CIL) have attained
remarkable success, as replaying the exemplars of old classes can significantly
mitigate catastrophic forgetting. Despite their effectiveness, the inherent
memory restrictions of CIL result in saving a limited number of exemplars with
poor diversity, leading to data imbalance and overfitting issues. In this
paper, we introduce a novel exemplar super-compression and regeneration method,
ESCORT, which substantially increases the quantity and enhances the diversity
of exemplars. Rather than storing past images, we compress images into visual
and textual prompts, e.g., edge maps and class tags, and save the prompts
instead, reducing the memory usage of each exemplar to 1/24 of the original
size. In subsequent learning phases, diverse high-resolution exemplars are
generated from the prompts by a pre-trained diffusion model, e.g., ControlNet.
To minimize the domain gap between generated exemplars and real images, we
propose partial compression and diffusion-based data augmentation, allowing us
to utilize an off-the-shelf diffusion model without fine-tuning it on the
target dataset. Therefore, the same diffusion model can be downloaded whenever
it is needed, incurring no memory consumption. Comprehensive experiments
demonstrate that our method significantly improves model performance across
multiple CIL benchmarks, e.g., 5.0 percentage points higher than the previous
state-of-the-art on 10-phase Caltech-256 dataset.