發(fā)布時間：2018-08-04 19:11

【摘要】：網(wǎng)絡(luò)技術(shù)的高速發(fā)展與醫(yī)療數(shù)字影像傳輸及通信(DICOM)標(biāo)準(zhǔn)的建立,在促進(jìn)數(shù)字醫(yī)療影像信息的交流的同時,也帶來了醫(yī)學(xué)數(shù)據(jù)在傳輸中可能出現(xiàn)的丟失或被篡改等信息安全問題。因此,對醫(yī)學(xué)數(shù)據(jù)的真實性及完整性進(jìn)行認(rèn)證是十分重要的。數(shù)字水印技術(shù)作為一種可將隱私信息直接嵌入載體信息中的新興信息安全技術(shù),被廣泛應(yīng)用于數(shù)字信息保護(hù)和認(rèn)證等領(lǐng)域。為能夠?qū)︶t(yī)學(xué)圖像的完整性進(jìn)行認(rèn)證,且不引入任何失真,設(shè)計出一種能無損恢復(fù)原始圖像,并能對圖像進(jìn)行完整性認(rèn)證的無損水印算法具有重要的意義。 本文主要成果性工作包括： (1)提出一種將壓擴(kuò)技術(shù)、差值擴(kuò)展技術(shù)與糾錯碼技術(shù)結(jié)合的水印算法。該算法利用了圖像中相鄰圖像間的灰度值相關(guān)性,通過對相鄰像素的差值擴(kuò)展來嵌入信息。并使用壓擴(kuò)技術(shù)實現(xiàn)對圖像失真的控制,及提高差值擴(kuò)展過程中得到的二值位置圖壓縮率,從而達(dá)到增大水印嵌入容量的目的。同時使用糾錯碼的糾錯特性提高圖像整體的自修復(fù)能力。 (2)在基于區(qū)域的醫(yī)學(xué)圖像無損水印算法上進(jìn)行改進(jìn),增添篡改恢復(fù)功能。該算法先確定感興趣區(qū)域,并將其作為認(rèn)證區(qū)域,獲取認(rèn)證信息作為水印信息的一份子；在感興趣區(qū)域外(非感興趣區(qū)域)自動選取嵌入?yún)^(qū)域；通過對相鄰像素進(jìn)行差值擴(kuò)展,實現(xiàn)非感興趣區(qū)域內(nèi)水印的嵌入；提取水印后,通過認(rèn)證信息的比較實現(xiàn)篡改定位檢測,通過糾錯碼技術(shù)實現(xiàn)篡改恢復(fù)的功能。最終,嵌入水印后圖像失真水平可通過輸入閾值進(jìn)行調(diào)節(jié)。與前一種算法相比無需嵌入壓縮后的標(biāo)識二值圖像,水印容量不再受二值圖像壓縮率影響,并在一定程度上能實現(xiàn)水印容量的提高,且該方法能將嵌入水印引起的失真限制在感興趣區(qū)域外,嵌入水印后的圖像也能直接用于醫(yī)學(xué)診斷或其他醫(yī)學(xué)應(yīng)用,方便了嵌入水印后醫(yī)學(xué)圖像的實際使用。
[Abstract]:The rapid development of network technology and the establishment of (DICOM) standard for medical digital image transmission and communication not only promote the exchange of digital medical image information, but also bring about information security problems such as the loss or tampering of medical data in transmission. Therefore, it is very important to authenticate the authenticity and integrity of medical data. As a new information security technology which can embed privacy information directly into carrier information, digital watermarking technology has been widely used in digital information protection and authentication. In order to authenticate the integrity of medical image without any distortion, it is of great significance to design a lossless watermarking algorithm that can restore the original image without loss and can authenticate the integrity of the image. The main achievements of this paper are as follows: (1) A watermarking algorithm combining compression spread, difference spread and error correction code is proposed. The algorithm makes use of the gray correlation between adjacent images and embeds information by extending the difference between adjacent pixels. The compression spread technique is used to control the image distortion and to increase the compression ratio of the binary position map in the process of the difference expansion, so as to increase the embedding capacity of the watermark. At the same time, the error-correcting characteristics of error-correcting codes are used to improve the overall self-repairing ability of the image. (2) to improve the lossless watermarking algorithm of medical image based on region, and to add the tampering recovery function. The algorithm first determines the region of interest and takes it as the authentication region to obtain the authentication information as a part of the watermark information; automatically selects the embedded region outside the region of interest (not the region of interest); and extends the difference between adjacent pixels. After extracting the watermark, the tamper location detection is realized by comparing the authentication information, and the tampering recovery function is realized by error correction code technology. Finally, the image distortion level after embedding watermark can be adjusted by input threshold. Compared with the former algorithm, the watermark capacity is no longer affected by the compression ratio of the binary image, and the watermark capacity can be improved to a certain extent. The method can limit the distortion caused by the embedded watermark to the region of interest, and the embedded image can also be directly used in medical diagnosis or other medical applications, thus facilitating the practical use of the medical image after embedding the watermark.
【學(xué)位授予單位】：東北大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2012
【分類號】：R318

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本文編號：2164866