نتایج جستجو برای: تصویر jpeg

تعداد نتایج: 21751  

Journal: : 2022

JPEG, görüntü sıkıştırma için en yaygın kullanılan yöntemlerin başında gelmektedir. JPEG işleminde kuantalama adımında tablosu önemli bir rol oynamaktadır. Kuantalama görüntünün kalitesini ve miktarını ölçüde belirler. Bu nedenle tablosunun oluşturulması optimizasyon problemi olarak görülmektedir. makalede daha etkili tabloları oluşturulabilmesi oran-bozulma yaklaşımı, insan görsel sistemi yakl...

آشکارسازی فشرده‌سازی مجدد، نقش مهمی در جرم‌کاوی تصاویر JPEG و تشخیص جعل دارد. در این مقاله، روش جدیدی برای تشخیص جعل بر اساس آشکارسازی فشرده‌سازی مجدد تصاویر دیجیتال با استفاده از ترکیب ویژگی‌های مبتنی بر اثر کوانتیزاسیون بر ضرایب DCT ارائه می‌شود. در روش پیشنهادی از ترکیب ویژگی‌های مبتنی بر توزیع ارقام اول ضرایب DCT و همچنین ویژگی‌های مبتنی بر پریود کوانتیزاسیون در ضرایب DCT هر سه کانال رنگی ت...

Journal: :IEEE transactions on image processing : a publication of the IEEE Signal Processing Society 1999
Jaehan In Shahram Shirani Faouzi Kossentini

Among the many different modes of operations allowed in the current JPEG standard, the sequential and progressive modes are the most widely used. While the sequential JPEG mode yields essentially the same level of compression performance for most encoder implementations, the performance of progressive JPEG depends highly upon the designed encoder structure. This is due to the flexibility the st...

2011
Yujin Zhang Shenghong Li Shilin Wang

Copy-paste forgery is a very common type of forgery in JPEG images. The tampered patch has always suffered from JPEG compression twice with inconsistent block segmentation. This phenomenon in JPEG image forgeries is called the shifted double JPEG (SD-JPEG) compression. Detection of SD-JPEG compressed blocks can make crucial contribution to detect and locate the tampered region. However, the exi...

2015
Thomas Richter Tim Bruylants Peter Schelkens Touradj Ebrahimi

The JPEG standard has known an enormous market adoption. Daily, billions of pictures are created, stored and exchanged in this format. The JPEG committee acknowledges this success and spends continued efforts in maintaining and expanding the standard specifications. JPEG XT is a standardization effort targeting the extension of the JPEG features by enabling support for high dynamic range imagin...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تحصیلات تکمیلی علوم پایه زنجان - دانشکده ریاضی 1392

چکیده در مبحث کدگذاری منبع، هدف اصلی متناظر کردن کدکلمه هایی به شکل دودویی برای ذخیره ی اطلاعات است که تعداد بیت های لازم برای هر کدکلمه کمترین تعداد باشد. این امر، سبب کاهش هزینه در ذخیره ی اطلاعات می شود. روش ها و الگوریتم های متفاوتی برای کدگذاری منبع ارائه شده اند که در این میان کدهای هافمن، کدهای بهینه هستند. در این پایان نامه، کدهای هافمن را مورد مطالعه قرار خواهیم داد. روش کدگذاری و کد...

2012
Fabian Zach Christian Riess Elli Angelopoulou

We present a method for automating the detection of the socalled JPEG ghosts. JPEG ghosts can be used for discriminating singleand double JPEG compression, which is a common cue for image manipulation detection. The JPEG ghost scheme is particularly well-suited for non-technical experts, but the manual search for such ghosts can be both tedious and error-prone. In this paper, we propose a metho...

2000
David A. Clunie

Proprietary compression schemes have a cost and risk associated with their support, end of life and interoperability. Standards reduce this cost and risk. The new JPEG-LS process (ISO/IEC 14495-1), and the lossless mode of the proposed JPEG 2000 scheme (ISO/IEC CD15444-1), new standard schemes that may be incorporated into DICOM, are evaluated here. Three thousand, six hundred and seventy-nine ...

2014
Sharmila Rani K. Sri Harsha

The JPEG[1] (Joint Photographic Experts Group) introduced a still image graphics format in 1987, known as JPEG. The process flow in the baseline mode, converts color images to 8x8 block based DCT mostly applied for gray images, then we applied quantization for the DCT in zigzag ordering, and obtained entropy coding using Huffman tables in the encoding process is obtained and vice versa for deco...

Abstract: JPEG is the most applicable image format in digital communication. In recent years, various steganography methods have been proposed for it. This paper aims to study and classify JPEG steganography schemes and introduce different methods to improve their security based on cover. Accordingly, the effective factors in security that are related to the cover such as double compression, sp...

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