- Research Article
- 10.37661/1816-0301-2025-22-4-36-54
Neural Networks Based on a Learnable Two-Dimensional Separable Transform for Image Classification: Theory and Hardware Implementation on FPGA
- Jan 02, 2026
- Informatics
- Egor A Krivalcevich + 1 more +1
Objectives. Development of methods for design compact and efficient neural networks for image recognition tasks, as well as their hardware implementation based on FPGA. Methods. The paper proposes the concept of a learnable two-dimensional separable transformation (LST) for designing feedforward neural networks for image recognition tasks. A feature of the LST is the sequential processing of image rows by a fully connected layer, after which the resulting representation is processed by columns using second fully connected layer. In the proposed architecture of a feedforward neural network, the LST is considered as a feature extractor. The hardware implementation of LST-based neural network is based on the concept of in-place computing (shared memory for storing source and intermediate data), as well as using a single set of computing cores to calculate all layers of the neural network. Results. A family of compact neural network architectures LST-1 is proposed, differing in the image embedding size. Experiments on the classification of MNIST handwritten digits have shown the high efficiency of these models: the LST-1-28 network achieves 98.37 % accuracy with 9.5 K parameters, and the more compact LST-1-8 shows 96.53 % accuracy with 1.1 K parameters. Testing of the LST-1-28 hardware implementation confirms the architecture's resistance to parameter quantization errors. Conclusion. The proposed concept of a learnable two-dimensional separable transformation provides the design of compact and efficient neural network architectures characterized by: a small number of learnable parameters, high recognition accuracy, and the regular structure of the algorithm, which makes it possible to obtain their effective implementations based on FPGAs.
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