Deteksi Pemalsuan Citra dengan Teknik Copy-Move Menggunakan Metode Ordinal Measure dari Koefisien Discrete Cosine Transform

Abstract

Abstrak-Artikel ini membahas tentang metode baru untuk deteksi citra palsu yang dihasilkan dari teknik copy-move. Teknik copy-move merupakan salah satu teknik pemalsuan citra dengan cara mengambil objek tertentu dari citra asli dan menambahkannya pada citra tersebut dengan tujuan untuk menambah jumlah atau merubah objek yang sama pada citra asli. Penelitian ini bertujuan untuk mendeteksi citra palsu yang dihasilkan oleh teknik copy-move dan citra palsu copy-move yang telah dimodifikasi dengan operasi rotasi dan ekualisasi histogram. Fitur deteksi yang digunakan adalah Ordinal Measure dari koefisien Discrete Cosine Transform (OM-DCT). Pendeteksian dimulai dengan membagi citra ke dalam blok berukuran BxB (B = 16x16, 32x32 dan 64x64) dan DCT 2 dimensi dilakukan pada setiap blok tersebut. Jarak fitur citra asli dengan palsu dihitung dengan persamaan jarak Ecluidian dan setiap fitur yang memiliki jarak lebih kecil atau sama dengan nilai threshold (T) menurut pengamatan akan ditandai sebagai bagian yang dipalsukan. Hasil pendeteksian menunjukkan bahwa ada blok-blok yang terdeteksi pada objek citra yang di-copy-move baik pada citra palsu copy-move yang tidak dimodifikasi ataupun yang telah dimodifikasi dengan operasi rotasi dan ekualisasi histogram. Jumlah blok yang ditemukan pada objek copy-move bervariasi sesuai ukuran blok pendeteksian yang digunakan. Kata kunci : Discrete Cosine Transform (DCT), ordinal measure dari koefisien DCT, copy-move, rotasi, ekualisasi histogram.Abstract-This article discusses a new method for the detection of forgery images generated by copy-move technique. Copy-move technique is one of image forgery techniques which taking a particular object from its original image and add it on that image for the purpose of increasing the number of or changing the same object in the original image. This study aims to detect the forged image generated by the copy-move techniques and copy-move forged image that has been modified by the rotation operation and histogram equalization. Detection feature used is Ordinal Measure of Discrete Cosine Transform coefficient (OM-DCT). Detection starts with division of the image into a block size of BXB (B = 16x16, 32x32 and 64x64) and two-dimensional DCT was performed to each of blocks. The feature distance from the original to the fake image, was calculated by the Euclidian distance and each feature has a distance of less than or equal to the threshold value (T) according to the observations will be marked as a forged part. The results show that there are blocks detected on the copy-move image, whether on the unmodified copy-move forge image or those which modified by the rotation operation and histogram equalization. The number of blocks that are found in the copy-move object varies according to the size of the detection block used.

Solo City Batik Design Security System (SiKemTi Solo) During the Pandemic Covid-19

“…The watermarking method with DCT as done (Saifuddin, Yogyakarta, Mido, & Yogyakarta, 2020) is used for steganography, as well as research conducted (Ardiansyah, Susilo, & Erlansari, 2017) used to insert information into the image to secure the image. The results obtained are no difference between the original image and the watermarked image as in the research conducted (Hardianto et al, 2017), (Zulfan & Muharar, 2016), (Agustina & Asmara, 2017) and (Ghonge, 2018) . For a home industry usually has many batik designs produced, but this design can be duplicated because there is no system that can help to secure the design as an identifier from the initial design owner as in the research conducted (Saputra, Fauziah, & Hayati, 2020) and (Zulfan & Muharar, 2016) and (Zhou, Bai, & Wang, 2015).…”

“…The results obtained are no difference between the original image and the watermarked image as in the research conducted (Hardianto et al, 2017), (Zulfan & Muharar, 2016), (Agustina & Asmara, 2017) and (Ghonge, 2018) . For a home industry usually has many batik designs produced, but this design can be duplicated because there is no system that can help to secure the design as an identifier from the initial design owner as in the research conducted (Saputra, Fauziah, & Hayati, 2020) and (Zulfan & Muharar, 2016) and (Zhou, Bai, & Wang, 2015). The existence of a compression system using watermarking allows a product design to be secured as was done in research , (Suheryadi, 2017) and (Ardiansyah et al, 2017) to be able to find out the owner of the initial design of the product so that Home industry craftsmen will feel the results of their work and can also continue to improve their creative works.…”

“…For this reason, it is important to develop a method that can be used for a system that can identify the original owner of a batik design at the Solo batik home industry so that the design works of the craftsmen can be identified by inserting or compressing their names in existing designs that will be uploaded to be marketed online. Like paper money, it will be seen which paper money is real and which is counterfeit as in the study (Zulfan & Muharar, 2016).…”

“…The results obtained are the watermarked images have a small decrease in quality with the average PSNR and MSE values around 34.08 and 14.62. Research conducted by (Zulfan & Muharar, 2016) in his research detects image falsification with the copy move technique, the detection feature used is the Ordinal Measure of the Discrete Cosine Transform (OM-DCT) coefficient. Detection begins by dividing the image into blocks of BxB size (B = 16x16, 32x32 and 64x64) and 2-dimensional DCT is performed on each of these blocks.…”

“…Research conducted by (Zulfan & Muharar, 2016) and (Rosadi et al, 2018) performed watermark insertion using the DCT method on digital images. This method was chosen because this method is more robust against image manipulation, especially compression.…”