Method and system of bitmap joint photographic experts group (JPEG) compression detection

Abstract

The invention discloses a method and a system of bitmap joint photographic experts group (JPEG) compression detection. The method of the bitmap JPEG compression detection includes the steps of diving bitmap data to be detected into blocks, calculating the corresponding discrete cosine transformation (DCT) coefficient matrix, converting the corresponding DCT coefficient matrix into corresponding integer matrix, obtaining a factor column diagram which shows respective occurrence times of various positive factors in the whole integer matrix, analyzing the monotony of the factor column diagram, obtaining a metric, judging whether the metric is larger than a preset threshold value nor not, determining that the bitmap to be detected goes through JPEG compression when the metric is larger than the preset threshold value, and determining that the bitmap to be detected does not go through the JPEG compression when the metric is not larger than the preset threshold value. According to the proposed factor column diagram, the method and the device of the bitmap JPEG compression detection can accurately judge whether the bitmap goes through the JPEG compression or not. Computation complexity is low and distinguish ability is good.

Description

technical field [0001] The invention relates to the field of image forensics, in particular to a bitmap JPEG compression detection method and system. Background technique [0002] JPEG is a lossy compression technology widely used in image capture equipment, which can effectively remove redundant information of images (such as visual redundancy, frequency redundancy, etc.), has a high file compression rate and detail fidelity, and A trade-off mechanism between the two is provided by selecting different compression quality factors (quality factor 100 corresponds to the highest detail fidelity, quality factor 1 corresponds to the lowest detail fidelity, and the commonly used quality factor is 50-100). [0003] With the development of image editing technology, the content of JPEG images may be maliciously tampered with for illegal purposes, and re-saved in the form of bitmap (Bitmap) after tampering. If these falsified bitmaps cannot be correctly identified, they may cause ser...

AI Technical Summary

Problems solved by technology

The disadvantage of this method is that the blockiness measure is easily affected by the texture of the bitmap itself

The disadvantage of this method is that a large number of DCT coefficients need to be collected to form a stable first digit histogram for accurate judgment, so when the bitmap size is small and cannot provide sufficient statistical data, the performance is not good

However, the disadvantage of this method is that the ability to judge the bitmap compressed by the high quality factor JPEG is not good.

[0010] It can be seen that the existing technology needs to analyze and count a large number of image blocks, the complexity is high, and the detection accuracy of small-sized image blocks is low; and because of the high-quality factor JPEG compression only leaves a slight Quantization effect, the existing technical solutions are easy to misjudge the bitmap compressed by the high quality factor JPEG as an uncompressed bitmap

For example, the JPEG images output by existing digital cameras usually only undergo slight JPEG compression, so the existing technology has limited discrimination ability when performing bitmap JPEG compression detection, which leads to poor recognition of bitmap sources.

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