應用於X光影像之衝擊濾波器硬體實現

Abstract

X-ray影像可能因為訊號的傳輸，或是鏡頭設計不良，導致影像的受到破壞。本論文提出了一個二級的衝擊濾波器的設計，演算法是以偏微分方程的基礎下來實現，目的為還原被模糊且含有雜訊的x-ray影像。而衝擊濾波器是一種知名的形態學處理的方法，被用於去除雜訊、邊緣強化和影像分群的應用上。根據實驗結果的效能，衝擊濾波器在x-ray影像的處理是非常優異的。在還原有雜訊x-ray影像的處理上，PSNR值都至少為38dB。而在強化模糊x-ray影像的處理上，影像的邊緣的銳利度也明顯上升。此外本論文還提出一個VLSI硬體架構，目的為加速高畫質影像(944p)的處理，而且最後也實現在可程式化邏輯陣列上。因為衝擊濾波器的運算處理複雜度不高，因此硬體消耗是低的。為了加速處理速度規格達到即時處理標準，本論文還使用了五個衝擊濾波器串聯的硬體架構，來實現高畫質x-ray影像的處理。最後整個硬體規格面積，在設計編輯器上為133k個邏輯閘，在可程式化邏輯陣列上為2904邏輯元件，速度上則是操作在100MHz，每秒處理43.1張944p影像。

X-ray image might be corrupted by noise or blurring because of the signal transmission or the bad x-ray lens. This paper presents a two-stage shock filter based on Partial Differential Equations (PDE) to restore noisy blurred x-ray image. Shock filters are popular morphological methods. They are used for noise removal, edge enhancement and image segmentation. Our experimental results show that the performances of the shock filter are excellent in x-ray image. The peak signal-to-noise ratio (PSNR) values are 38dB at least in restoring the noisy x-ray image. The sharpness of the image’s edges increase in enhancing the blurred x-ray image. Furthermore, this paper proposes a VLSI architecture for accelerating the high-definition (HD) x-ray image (944p) process. This paper implements the architecture in FPGA. The hardware cost is low because the computation of the shock filter is low complex. To achieve the real-time processing specification, this paper uses a 5-series shock filter architecture to implement computation of HD x-ray image. This paper demonstrates a 944p, 43.1-fps solution on 100MHz with 133k gate counts in Design Compiler, and with 2904 logic elements in FPGA.