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A cascadable stereo matching processor with pixel-wise fusion for extended depth sensing

Zhuoyu Chen1, Pingcheng Dong2, Zhiyong Lai1, Wenyue Zhang1, Xianglong Wang1, Lei Chen1 and Fengwei An1,

+ Author Affiliations

 Corresponding author: Fengwei An, anfw@sustech.edu.cn

DOI: 10.1088/1674-4926/25120024CSTR: 32376.14.1674-4926.25120024

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Abstract: Achieving long-range, high-accuracy depth perception under stringent power constraints remains a critical challenge for stereo vision in edge applications. This work presents a cascadable stereo matching processor that overcomes the inherent trade-off between sensing range and computational efficiency. The core innovation is a scalable semi-global matching (SSGM) algorithm which dynamically optimizes the disparity search range for different baselines, ensuring constant on-chip memory usage and a significant reduction in data movement. The architecture further integrates a raw-domain rectification front-end, which performs direct geometric transformation on Bayer-patterned image streams. This approach eliminates the need for external memory access by bypassing conventional ISP pipelines, thereby maximizing throughput and reducing system memory consumption. Parallel processing paths for multiple baselines converge in a pixel-wise fusion module, which synthesizes a unified depth map by selecting the most reliable disparity estimate for each output pixel. The cascadable stereo matching processor achieves speedups of up to 178x and 97x over CPU and EdgeGPU platforms, respectively, in multi-baseline stereo disparity fusion. Implemented in 40-nm CMOS technology, the processor operates at 160 MHz, achieving a processing speed of 80 frames per second with an energy efficiency of 7.9 pJ/pixel and occupying a core area of 6.04 mm2.

Key words: hardware architecturestereo visionreal-time systemmulti-baseline stereodisparity fusion



[1]
Wang Y, Chao W L, Garg D, et al. Pseudo-LiDAR from visual depth estimation: Bridging the gap in 3D object detection for autonomous driving. 2019 IEEE/CVF Conference on Computer Vision and Pattern Recognition (CVPR), 2019: 8437
[2]
Menze M, Geiger A. Object scene flow for autonomous vehicles. 2015 IEEE Conference on Computer Vision and Pattern Recognition (CVPR), 2015: 3061
[3]
Wang H, Sridhar S, Huang J W, et al. Normalized object coordinate space for category-level 6D object pose and size estimation. 2019 IEEE/CVF Conference on Computer Vision and Pattern Recognition (CVPR), 2019: 2637
[4]
Sheikh T S, Afanasyev I M. Stereo vision-based optimal path planning with stochastic maps for mobile robot navigation. Intelligent Autonomous Systems 15. Cham: Springer International Publishing, 2019: 575
[5]
Rasla A, Beyeler M. The relative importance of depth cues and semantic edges for indoor mobility using simulated prosthetic vision in immersive virtual reality. Proceedings of the 28th ACM Symposium on Virtual Reality Software and Technology, 2022: 1
[6]
Tippetts B, Lee D J, Lillywhite K, et al. Review of stereo vision algorithms and their suitability for resource-limited systems. J Real Time Image Process, 2016, 11(1): 5 doi: 10.1007/s11554-012-0313-2
[7]
Hirschmüller H. Accurate and efficient stereo processing by semi-global matching and mutual information. 2005 IEEE Computer Society Conference on Computer Vision and Pattern Recognition (CVPR'05), 2005: 807
[8]
Xu G W, Wang X Q, Ding X H, et al. Iterative geometry encoding volume for stereo matching. 2023 IEEE/CVF Conference on Computer Vision and Pattern Recognition (CVPR), 2023: 21919
[9]
Shamsafar F, Woerz S, Rahim R, et al. MobileStereoNet: Towards lightweight deep networks for stereo matching. 2022 IEEE/CVF Winter Conference on Applications of Computer Vision (WACV), 2022: 677
[10]
Zhang Y, Chen G, He T, et al. ViraEye: An energy-efficient stereo vision accelerator with binary neural network in 55 nm CMOS. Proceedings of the 28th Asia and South Pacific Design Automation Conference, 2023: 178
[11]
Min F, Xu H B, Wang Y, et al. Dadu-eye: A 5.3 TOPS/W, 30 fps/1080p high accuracy stereo vision accelerator. IEEE Trans Circuits Syst I, 2021, 68(10): 4207 doi: 10.1109/tcsi.2021.3101296
[12]
Choi S, Lee J, Lee K, et al. A 9.02mW CNN-stereo-based real-time 3D hand-gesture recognition processor for smart mobile devices. 2018 IEEE International Solid-State Circuits Conference (ISSCC), 2018: 220
[13]
Wang H Y, Zhou W, Zhang X Y, et al. A 39pJ/label 1920×1080 165.7 FPS Block PatchMatch based stereo matching processor on FPGA. 2022 IEEE Custom Integrated Circuits Conference (CICC), 2022: 1
[14]
Jiang Y C, Yu Y, Li H, et al. A configurable local-expansion-move accelerator for accurate stereo matching. IEEE Trans Circuits Syst II, 2024, 71(7): 3518 doi: 10.1109/tcsii.2024.3364491
[15]
Gallup D, Frahm J M, Mordohai P, et al. Variable baseline/resolution stereo. 2008 IEEE Conference on Computer Vision and Pattern Recognition, 2008: 1
[16]
Dong P C, Chen Z Y, Li Z A, et al. A 4.29nJ/pixel stereo depth coprocessor with pixel level pipeline and region optimized semi-global matching for IoT application. IEEE Trans Circuits Syst I Regul Pap, 2022, 69(1): 334 doi: 10.1109/TCSI.2021.3100071
[17]
Ling Y H, He T, Zhang Y, et al. Lite-stereo: A resource-efficient hardware accelerator for real-time high-quality stereo estimation using binary neural network. IEEE Trans Comput Aided Des Integr Circuits Syst, 2022, 41(12): 5357 doi: 10.1109/TCAD.2022.3163629
[18]
Li Z Y, Wang J C, Sylvester D, et al. A 1920 × 1080 25-frames/s 2.4-TOPS/W low-power 6-D vision processor for unified optical flow and stereo depth with semi-global matching. IEEE J Solid State Circuits, 2019, 54(4): 1048 doi: 10.1109/JSSC.2018.2885559
[19]
Li J, Zhang C L, Yang W X, et al. FPGA-based low-bit and lightweight fast light field depth estimation. IEEE Trans Very Large Scale Integr (VLSI) Syst, 2025, 33(1): 88 doi: 10.1109/TVLSI.2024.3496751
[20]
Junger C, Fütterer R, Rosenberger M, et al. FPGA-based multi-view stereo system with flexible measurement setup. Meas Sens, 2022, 24: 100425 doi: 10.1016/j.measen.2022.100425
[21]
Sato T, Yokoya N. Efficient hundreds-baseline stereo by counting interest points for moving omni-directional multi-camera system. J Vis Commun Image Represent, 2010, 21(5/6): 416 doi: 10.1016/j.jvcir.2010.02.006
[22]
Lu Z M, Wang J, Li Z W, et al. A resource-efficient pipelined architecture for real-time semi-global stereo matching. IEEE Trans Circuits Syst Video Technol, 2022, 32(2): 660 doi: 10.1109/TCSVT.2021.3061704
[23]
Dong P C, Chen Z Y, Li K, et al. A 1920 × 1080 129fps 4.3pJ/pixel stereo-matching processor for pico aerial vehicles. ESSCIRC 2023- IEEE 49th European Solid State Circuits Conference (ESSCIRC), 2023: 345
[24]
Dosovitskiy A, Ros G, Codevilla F, et al. CARLA: An open urban driving simulator. Proceedings of the 1st Annual Conference on Robot Learning, 2017: 1
[25]
Dong P C, Chen Z Y, Li Z A, et al. Configurable image rectification and disparity refinement for stereo vision. IEEE Trans Circuits Syst II, 2022, 69(10): 3973
[26]
Hübert H, Stabernack B, Zilly F. Architecture of a low latency image rectification engine for stereoscopic 3-D HDTV processing. IEEE Trans Circuits Syst Video Technol, 2013, 23(5): 813 doi: 10.1109/TCSVT.2012.2223795
[27]
Akin A, Baz I, Gaemperle L M, et al. Compressed look-up-table based real-time rectification hardware. 2013 IFIP/IEEE 21st International Conference on Very Large Scale Integration (VLSI-SoC), 2013: 272
[28]
Zhang W Y, Dong P C, Chen L, et al. Min-pooling cost aggregation for semi-global matching of stereo vision processor. IEEE Trans Circuits Syst II, 2025, 72(1): 258 doi: 10.1109/tcsii.2024.3463200
[29]
Geiger A, Lenz P, Urtasun R. Are we ready for autonomous driving? The KITTI vision benchmark suite. 2012 IEEE Conference on Computer Vision and Pattern Recognition, 2012: 3354
Fig. 1.  (Color online) The challenges in stereo matching for extended depth sensing. (a) Motivation of the this work. (b) Lack of Multi-Baseline Stereo Rectification and Pixel-wise Disparity Fusion for Stereo Mathcing. (c) Exponential Depth-Sensing Error and Resource Inefficiency in Non-Scalable Binocular Stereo Systems. (d) Mainstream MVS algorithm's high memory consumption and hardware implementation inefficiency.

Fig. 2.  Dataflow of the proposed cascadable stereo matching algorithm.

Fig. 3.  (Color online) Overall architecture of cascadable stereo processor.

Fig. 4.  (Color online) Raw-domain stereo rectification architecture with configurable buffer.

Fig. 5.  (Color online) Pixel-wise disparity fusion architecture.

Fig. 6.  (Color online) The ablation studies of regional optimization. (a) D1-all error rate under different grouping factors. (b) End-point error under different grouping factors. (c) Accuracy-memory trade-off analysis.

Fig. 7.  (Color online) (a)Accuracy comparison of cascaded trinocular vs. binocular systems at different distances. (b) Multi-baseline fusion throughput comparison

Fig. 8.  (Color online) The test setup.

Fig. 9.  (Color online) The die photo.

Fig. 10.  (Color online) Results of the proposed system in real-world scenes, displaying input images, disparity maps, and 3D reconstructions.

Fig. 11.  (Color online) Raw-domain stereo rectification memory consumption.

Table 1.   Comparison with other dedicated rectification hardware implementations.

WorkThis workTCASII 2022[25]TCSVT 2013[26]VLSI 2013[27]
Mapping MethodOn the flyOn the flyOn the flyPre-computed
EMA*1NoNoYesNo
Data formatRAWGrayscaleRGBRGB
FPGA PlatformXilinx VU9PAltera Stratix IVAltera Stratix IIIXilinx Virtex-5
LUT358634596987784
Memory*2912Kb1243Kb1970Kb3045Kb
Frequency128MHz105MHz62MHz112MHz
*1: External Memory Access *2 Scaled to 1920×1080 resolution with 8 bit grayscale data and 10% distortion.
DownLoad: CSV

Table 2.   Comparison with state-of-art stereo matching processors.

Work This work TCASII
2025[28]
TCASII
2024[14]
ASP-DAC
2023[10]
TCSVT
2022[22]
CICC
2022[13]
JSSC
2019[18]
Method SSGM+GIF Min-pooling CNN+LE BNN+SGM SGM Patch Match NG-SGM
Tech/FPGA 40 nm 28 nm Xilinx xczu15eg 28 nm Xilinx ZCU102 Xilinx ZCU102 28 nm
Resolution 1920×1080 1920×1080 1242×375 1024×768 1280×960 1920×1080 1920×1080
EMA*1 wo*3 wo w*3 wo*3 w*3 wo*3 wo*3
Freq(MHz) 160 200 300 142 148.5 350 180
Area/LUTs 6.04 mm2 3.3 mm2 165.9K 12.4 mm2 N.A N.A 9.3 mm2
Norm.Area(mm2)*4 6.04 6.74 N.A 25.3 N.A N.A 19.0
On-chip memory 4.34 Mb 2.18 Mb 9.78 Mb 5.778 Mb 8.06 Mb 10.26 Mb 1.61 Mb
Search range 256 256 192 64 128 128 128
Throughput 80fps@0.9V 50.15fps 15.4fps 181fps@1.2V 71.6fps 165.7fps 30fps@0.75V
Normalized energy*2 7.9pJ N.A N.A 12pJ N.A 72.8pJ 69pJ
Cascadable Yes No No No No No No
Performance
(Error rate)
7.12%(KT15)
5.64%(KT12)
N.A 5.45%
(KT15)
- 7.44%
(KT15)
6.31%
(KT15)
11.7%
(KT12)
*1: External Memory Access *2: Normalized energy=power/(search range×resolution×fps) *3: wo=without; w=with *4 Normalized Area is calculated as $ \text{Are}{\mathrm{a}}_{\text{meas}}\times (40\;\mathrm{nm}/\text{Tec}{\mathrm{h}}_{\text{node}}{)}^{2} $.
DownLoad: CSV
[1]
Wang Y, Chao W L, Garg D, et al. Pseudo-LiDAR from visual depth estimation: Bridging the gap in 3D object detection for autonomous driving. 2019 IEEE/CVF Conference on Computer Vision and Pattern Recognition (CVPR), 2019: 8437
[2]
Menze M, Geiger A. Object scene flow for autonomous vehicles. 2015 IEEE Conference on Computer Vision and Pattern Recognition (CVPR), 2015: 3061
[3]
Wang H, Sridhar S, Huang J W, et al. Normalized object coordinate space for category-level 6D object pose and size estimation. 2019 IEEE/CVF Conference on Computer Vision and Pattern Recognition (CVPR), 2019: 2637
[4]
Sheikh T S, Afanasyev I M. Stereo vision-based optimal path planning with stochastic maps for mobile robot navigation. Intelligent Autonomous Systems 15. Cham: Springer International Publishing, 2019: 575
[5]
Rasla A, Beyeler M. The relative importance of depth cues and semantic edges for indoor mobility using simulated prosthetic vision in immersive virtual reality. Proceedings of the 28th ACM Symposium on Virtual Reality Software and Technology, 2022: 1
[6]
Tippetts B, Lee D J, Lillywhite K, et al. Review of stereo vision algorithms and their suitability for resource-limited systems. J Real Time Image Process, 2016, 11(1): 5 doi: 10.1007/s11554-012-0313-2
[7]
Hirschmüller H. Accurate and efficient stereo processing by semi-global matching and mutual information. 2005 IEEE Computer Society Conference on Computer Vision and Pattern Recognition (CVPR'05), 2005: 807
[8]
Xu G W, Wang X Q, Ding X H, et al. Iterative geometry encoding volume for stereo matching. 2023 IEEE/CVF Conference on Computer Vision and Pattern Recognition (CVPR), 2023: 21919
[9]
Shamsafar F, Woerz S, Rahim R, et al. MobileStereoNet: Towards lightweight deep networks for stereo matching. 2022 IEEE/CVF Winter Conference on Applications of Computer Vision (WACV), 2022: 677
[10]
Zhang Y, Chen G, He T, et al. ViraEye: An energy-efficient stereo vision accelerator with binary neural network in 55 nm CMOS. Proceedings of the 28th Asia and South Pacific Design Automation Conference, 2023: 178
[11]
Min F, Xu H B, Wang Y, et al. Dadu-eye: A 5.3 TOPS/W, 30 fps/1080p high accuracy stereo vision accelerator. IEEE Trans Circuits Syst I, 2021, 68(10): 4207 doi: 10.1109/tcsi.2021.3101296
[12]
Choi S, Lee J, Lee K, et al. A 9.02mW CNN-stereo-based real-time 3D hand-gesture recognition processor for smart mobile devices. 2018 IEEE International Solid-State Circuits Conference (ISSCC), 2018: 220
[13]
Wang H Y, Zhou W, Zhang X Y, et al. A 39pJ/label 1920×1080 165.7 FPS Block PatchMatch based stereo matching processor on FPGA. 2022 IEEE Custom Integrated Circuits Conference (CICC), 2022: 1
[14]
Jiang Y C, Yu Y, Li H, et al. A configurable local-expansion-move accelerator for accurate stereo matching. IEEE Trans Circuits Syst II, 2024, 71(7): 3518 doi: 10.1109/tcsii.2024.3364491
[15]
Gallup D, Frahm J M, Mordohai P, et al. Variable baseline/resolution stereo. 2008 IEEE Conference on Computer Vision and Pattern Recognition, 2008: 1
[16]
Dong P C, Chen Z Y, Li Z A, et al. A 4.29nJ/pixel stereo depth coprocessor with pixel level pipeline and region optimized semi-global matching for IoT application. IEEE Trans Circuits Syst I Regul Pap, 2022, 69(1): 334 doi: 10.1109/TCSI.2021.3100071
[17]
Ling Y H, He T, Zhang Y, et al. Lite-stereo: A resource-efficient hardware accelerator for real-time high-quality stereo estimation using binary neural network. IEEE Trans Comput Aided Des Integr Circuits Syst, 2022, 41(12): 5357 doi: 10.1109/TCAD.2022.3163629
[18]
Li Z Y, Wang J C, Sylvester D, et al. A 1920 × 1080 25-frames/s 2.4-TOPS/W low-power 6-D vision processor for unified optical flow and stereo depth with semi-global matching. IEEE J Solid State Circuits, 2019, 54(4): 1048 doi: 10.1109/JSSC.2018.2885559
[19]
Li J, Zhang C L, Yang W X, et al. FPGA-based low-bit and lightweight fast light field depth estimation. IEEE Trans Very Large Scale Integr (VLSI) Syst, 2025, 33(1): 88 doi: 10.1109/TVLSI.2024.3496751
[20]
Junger C, Fütterer R, Rosenberger M, et al. FPGA-based multi-view stereo system with flexible measurement setup. Meas Sens, 2022, 24: 100425 doi: 10.1016/j.measen.2022.100425
[21]
Sato T, Yokoya N. Efficient hundreds-baseline stereo by counting interest points for moving omni-directional multi-camera system. J Vis Commun Image Represent, 2010, 21(5/6): 416 doi: 10.1016/j.jvcir.2010.02.006
[22]
Lu Z M, Wang J, Li Z W, et al. A resource-efficient pipelined architecture for real-time semi-global stereo matching. IEEE Trans Circuits Syst Video Technol, 2022, 32(2): 660 doi: 10.1109/TCSVT.2021.3061704
[23]
Dong P C, Chen Z Y, Li K, et al. A 1920 × 1080 129fps 4.3pJ/pixel stereo-matching processor for pico aerial vehicles. ESSCIRC 2023- IEEE 49th European Solid State Circuits Conference (ESSCIRC), 2023: 345
[24]
Dosovitskiy A, Ros G, Codevilla F, et al. CARLA: An open urban driving simulator. Proceedings of the 1st Annual Conference on Robot Learning, 2017: 1
[25]
Dong P C, Chen Z Y, Li Z A, et al. Configurable image rectification and disparity refinement for stereo vision. IEEE Trans Circuits Syst II, 2022, 69(10): 3973
[26]
Hübert H, Stabernack B, Zilly F. Architecture of a low latency image rectification engine for stereoscopic 3-D HDTV processing. IEEE Trans Circuits Syst Video Technol, 2013, 23(5): 813 doi: 10.1109/TCSVT.2012.2223795
[27]
Akin A, Baz I, Gaemperle L M, et al. Compressed look-up-table based real-time rectification hardware. 2013 IFIP/IEEE 21st International Conference on Very Large Scale Integration (VLSI-SoC), 2013: 272
[28]
Zhang W Y, Dong P C, Chen L, et al. Min-pooling cost aggregation for semi-global matching of stereo vision processor. IEEE Trans Circuits Syst II, 2025, 72(1): 258 doi: 10.1109/tcsii.2024.3463200
[29]
Geiger A, Lenz P, Urtasun R. Are we ready for autonomous driving? The KITTI vision benchmark suite. 2012 IEEE Conference on Computer Vision and Pattern Recognition, 2012: 3354
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    Received: 13 December 2025 Revised: 18 February 2026 Online: Accepted Manuscript: 24 March 2026

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      Zhuoyu Chen, Pingcheng Dong, Zhiyong Lai, Wenyue Zhang, Xianglong Wang, Lei Chen, Fengwei An. A cascadable stereo matching processor with pixel-wise fusion for extended depth sensing[J]. Journal of Semiconductors, 2026, In Press. doi: 10.1088/1674-4926/25120024 ****Z Y Chen, P C Dong, Z Y Lai, W Y Zhang, X L Wang, L Chen, and F W An, A cascadable stereo matching processor with pixel-wise fusion for extended depth sensing[J]. J. Semicond., 2026, accepted doi: 10.1088/1674-4926/25120024
      Citation:
      Zhuoyu Chen, Pingcheng Dong, Zhiyong Lai, Wenyue Zhang, Xianglong Wang, Lei Chen, Fengwei An. A cascadable stereo matching processor with pixel-wise fusion for extended depth sensing[J]. Journal of Semiconductors, 2026, In Press. doi: 10.1088/1674-4926/25120024 ****
      Z Y Chen, P C Dong, Z Y Lai, W Y Zhang, X L Wang, L Chen, and F W An, A cascadable stereo matching processor with pixel-wise fusion for extended depth sensing[J]. J. Semicond., 2026, accepted doi: 10.1088/1674-4926/25120024

      A cascadable stereo matching processor with pixel-wise fusion for extended depth sensing

      DOI: 10.1088/1674-4926/25120024
      CSTR: 32376.14.1674-4926.25120024
      More Information
      • Zhuoyu Chen received the bachelor’s degree from the Southern University of Science and Technology, China, in 2022, where he is currently pursuing the Ph.D. degree with the School of Microelectronics. His research primarily focuses on stereo vision processor, high-performance custom AI accelerators, and hardware-software co-design
      • Pingcheng Dong (Graduate Student Member, IEEE) received the BEng degree from the Southern University of Science and Technology in 2022. He is currently pursuing the Ph.D. degree with The Hong Kong University of Science and Technology. His research interests include stereo matching accelerator, model compression, AI chip, and hardware-software co-design
      • Zhiyong Lai received the bachelor’s degree from the University of Science and Technology of China, in 2024. He is currently pursuing the master’s degree with the School of Microelectronics, Southern University of Science and Technology. His research primarily focuses on image processing algorithms, custom AI accelerators, and hardware-software co-design
      • Wenyue Zhang received the bachelor’s degree from the Southern University of Science and Technology in 2022. She is currently pursuing the dual Ph.D. degree with the Southern University of Science and Technology and Pengcheng Laboratory. Her current research interests include computer vision and the design of AI accelerators
      • Xianglong Wang received the bachelor’s degree from the Southern University of Science and Technology, China, in 2020, where he is currently pursuing the Ph.D. degree with the School of Microelectronics. His research interests include design of energy-efficient hardware algorithms for image processing
      • Lei Chen received the B.S. and M.S. degrees from Qingdao University of Science and Technology in 2006 and 2009, respectively, and the Ph.D. degree from Hiroshima University, Higashihiroshima, Japan, in 2012.,Since October 2012, she has been doing her post-doctoral research with the HiSIM Research Center, Hiroshima University. From 2018 to 2020, she was with Sharp Company Ltd. Then, she was with the Peng Cheng Laboratory, Shenzhen, China, from 2020 to 2021. She is currently a Research Associate Professor with the Southern University of Science and Technology, Shenzhen. Her research interests include circuit design and hardware algorithm design for image processing and video compression
      • Fengwei An:An Fengwei (Member, IEEE) received the bachelor’s and master’s degrees from Qingdao University of Science and Technology, China, in 2006 and 2010, respectively, and the Ph.D. degree from Hiroshima University, Japan, in 2013., He is currently an Associate Professor with Shenzhen-Hong Kong Institute of Microelectronics, Southern University of Science and Technology (SUSTech). He has held significant positions, including an Associate Professor with Hiroshima University and a Chief Engineer with Panasonic Semiconductor Company Ltd., Japan. Since March 2019, he has been with SUSTech. His work has been published in top journals and conferences. He holds nine Chinese invention patents and three Japanese patents. His research interests include high-performance video image processing chips and AI/digital signal processing chips., Dr. Fengwei is a member of ACM. He was a recipient of the 2023 Outstanding Teaching Award from SUSTech, the APCCAS 2022 Best Paper Nomination Award, the PrimeAsia 2022 Bronze Leaf Award, and the Second Prize of the 2020 Wu Wenjun Artificial Intelligence Science and Technology Award
      • Corresponding author: anfw@sustech.edu.cn
      • Received Date: 2025-12-13
      • Revised Date: 2026-02-18
      • Available Online: 2026-03-24

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