Method and device for removing salt and pepper noise

Abstract

The invention discloses a method for removing salt and pepper noise. The method comprises the following steps: carrying median filtering on an input noise image; differentiating a median filtering result and the input noise image and determining noise candidate points based on the differentiating result; carrying out edge detection on the median filtering result to obtain edge minutiae; eliminating the edge minutiae with differential absolute values less than a first threshold value in the noise candidate points, thus obtaining a real noise point; and carrying out local median filtering on the real noise point, thus forming a de-noised image subjected to salt and pepper noise removal. Correspondingly, the invention also provides a device for removing the salt and pepper noise. The device comprises a noise candidate point acquiring module, an edge minutia acquiring module, a real noise point acquiring module and a local median filtering module.

Description

technical field [0001] The invention relates to image processing technology, in particular to a method and device for removing salt and pepper noise. Background technique [0002] In recent years, digital photoelectric imaging equipment has been widely used in digital photography, security monitoring, resource census and other fields. Most digital optoelectronic imaging devices are based on Charge Coupled Device (CCD) or Complementary Metal Oxide Semiconductor (CMOS) image sensors. In the imaging process based on CCD or CMOS image sensor, the quality of the image will inevitably be affected by the influence of optical noise, noise of components such as resistors and capacitors, sensor noise, circuit noise, thermal noise and readout noise, such as Generate salt and pepper noise. The so-called salt-and-pepper noise usually appears as individual bright or dark isolated noise points on the acquired image. The impact of various forms of noise makes the post-processing such as ...

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Problems solved by technology

[0006] However, the edge-preserving adaptive image filtering method disclosed in the Chinese invention patent No. 200610043000.5 directly uses local extrema as noise points. This operation may misjudge edge details as noise; The number of noise points in the window, and when there is no noise point, expand the window until the noise point is included, and then perform median filtering, even when the noise point is not found in the 5×5 filtering window, replace it with the mean value of 4 adjacent pixels after filtering , this kind of processing not only increases the operation redundancy, but also reduces the gray value precision of some pixels

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