NAND 快閃記憶體 (NAND flash memory) 被廣泛的運用在安全數
位卡 (SD card) 以及嵌入式多媒體控制器晶片 (eMMC chip) 等固態硬
碟 (SSD) 儲存裝置中，在這些裝置裡頭，JPEG 圖片是最珍貴的資料
之一。在本篇論文中，我們研究考量 NAND 快閃記憶體的特性來達到
JPEG 圖像的長期保存與修復之設計。其目標是加強存在快閃記憶體中的
JPEG 可靠度以及修復由於長時間保存而資料損毀的 JPEG 檔案，並且
JPEG 圖像經過所提出的機制處理後，仍保持兼容現有的 JPEG 開圖軟
體。我們執行了真實系統的實驗將 JPEG 檔案儲存於 16 奈米、三層單元
(3-bit-per-cell) 的快閃記憶體晶片中，並使 JPEG 檔案經歷了等同於在
25°C 下 10 年的保存時間。我們首先提出兩個所觀察到的錯誤蔓延的現象
– 位元錯誤蔓延以及 DC 值錯誤蔓延，接著針對所觀察到的現象，提出了
三個技術來試著降低錯誤蔓延所造成圖片品質的影響，藉以達成第一個目
標：加強在快閃記憶體中的 JPEG 可靠度。在修復方面，我們提出霍夫
曼輔助錯誤修正並利用循環冗餘校驗來幫助位元翻轉程序修復位元錯誤。
實驗結果顯示所提出的機制可以修復損毀的 JPEG 檔案並且可以達程最
高 25.4 dB 的峰值信噪比 (PSNR) 的提昇，所需付出相對於原始檔案大
小的額外儲存成本為 10.5%。相關研究成果也已於 2019 年 5 月在美國聖
塔克拉拉舉辦的國際巨量儲存系統技術研討會 (International Conference
on Massive Storage Systems and Technology, MSST 2019) 演講發表。

NAND flash memory is widely used in solid-state storage including
SD cards and eMMC chips, in which JPEG pictures are one of the most valuable data. In this thesis, I study NAND flash memory-aware, longterm JPEG data protection and recovery. My goal is to increase the robustness of JPEG files stored in flash-based storage and rescue JPEG files that are corrupted due to long-term retention. JPEG files with my proposed protection techniques are compatible with existing JPEG viewers. I conduct real-system experiments by storing JPEG files on 16 nm, 3-bit-per-cell flash chips and let the JPEG files undergo a retention process equivalent to ten years at 25°C. I first show two observed
error propagation phenomena – bit error propagation and DC error
propagation, and propose three techniques to help mitigating the effect of error propagation and thus to increase the robustness of JPEG files. As for correction, I propose Huffman-assisted error correction which utilize CRC (cyclic redundancy check) to help bit-flipping procedure. Experimental results show that the proposed techniques can rescue corrupted JPEG files to achieve a PSNR improvement of up to 25.4 dB with storage overhead 10.5% compared to original data size. The design and experimental results of this thesis have been accepted as an oral presentation at International Conference on Massive Storage Systems and Technology (MSST) held May 20-24, 2019 at Santa Clara
University, Santa Clara, USA.

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