Method for detecting digital zoom times of digital photo

A digital zoom and detection method technology, applied in image data processing, instruments, calculations, etc., can solve the problems of poor detection accuracy and complex implementation, and achieve the effect of simple and high detection accuracy

Inactive Publication Date: 2010-11-10
SHANGHAI UNIVERSITY OF ELECTRIC POWER
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Problems solved by technology

[0012] The above-mentioned existing technologies may only be able to detect high-quality uncompressed images during implementation, but most of the current digital photos are stored in the form of JPEG compression; or it is necessary to obtain the PRNU characteristic signal of the original digital camera, which is relatively complicated to implement and has high detection accuracy. poor

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  • Method for detecting digital zoom times of digital photo
  • Method for detecting digital zoom times of digital photo
  • Method for detecting digital zoom times of digital photo

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Embodiment Construction

[0027] A preferred embodiment of the present invention is described in detail as follows in conjunction with accompanying drawing:

[0028] Such as figure 2 As shown, this embodiment provides a method for detecting the digital zoom factor of a digital photo. For digital photos that may be obtained through digital zooming, first convert them into YCbCr space, then perform Laplace filtering on the brightness components in them, take the absolute value of the filtering results and average them in the horizontal direction to get a vector, in which The end of the vector is filled with zeros so that its length is an integer power of two to obtain the vector V, and then the discrete Fourier transform is performed on V to calculate the amplitude spectrum P=log 10 (1+|DFT(V)|), draw a normalized frequency-amplitude spectrogram, and determine the digital zoom factor of the photo by detecting the frequency corresponding to the peak in the frequency-amplitude spectrogram.

[0029] Conc...

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Abstract

The invention relates to a method for detecting the digital zoom times of a digital photo, which comprises the following steps of: converting the digital photo to be detected into a YCbCr space; filtering the luminance component in the digital photo by means of laplace; taking an absolute value of a filtering result to obtain a mean value according to the horizontal direction so as to obtain a vector quantity; filling zero to the tail of the vector quantity, so that the length of the vector quantity is the integral number power value of 2 to obtain a vector quantity V; converting the V by means of discrete Fourier to compute an amplitude spectrum P=log10 (1+ / DFT(v) / ); drawing a normalized frequency-amplitude spectrogram; and defining the digital zoom times of the photo by detecting the frequency which correspond to a peak value in the frequency-amplitude spectrogram. The method is completely not influenced by the compressing and storing quality factor of the JPEG of a digital camera, is completely independent of the EXIF information of the photo and the PRNU characteristic signal of an original digital camera, and realizes simpler and higher detection precision.

Description

technical field [0001] The invention relates to a method for digital zooming multiples of photos, in particular to a method for detecting digital zooming multiples of digital photos by using signal processing and computer technology. Background technique [0002] Digital zoom (Digital Zoom), also known as digital zoom, is when the lens of the digital camera is fixed and in a fixed focal length state, through the processor in the digital camera, a part of the pixels on the CCD image sensor are selected according to the selected The zoom factor uses interpolation operation to zoom in to the whole screen, such as figure 1 shown. Optical zoom (Optical Zoom) is to change the focal length of the lens and the viewing angle of the lens by moving the zoom lens group of the lens part back and forth, so as to realize the enlargement and reduction of the image. Different from optical zoom, digital zoom gives people a zoom effect by changing the vertical direction of the photosensitive...

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Application Information

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IPC IPC(8): G06T7/00
Inventor 魏为民
Owner SHANGHAI UNIVERSITY OF ELECTRIC POWER
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