Research On Image Enhancement Based On Wavelet Transform

In a real application,the image acquisition,compression,encoding,storage,communication and display process may be affected by the surrounding environment,human factors and their own hardware equipment,which often leads to problems such as low overall brightness,low contrast,partial color distortion,blurring and the introduction of noise in the image we acquire,these problems make the information conveyed by the image unable to be recognized and read normally by humans or machines,and it is difficult to obtain valuable information from it.Therefore,it is very necessary to develop an enhanced algorithm that can obtain useful information in images to facilitate people’s lives.Image enhancement means that the human eye can’t distinguish,the low-brightness image becomes clearly visible,and the part that people need is highlighted.At the same time to meet people’s pursuit of high-quality images,and to reduce the burden for subsequent work.In this paper,daily low-illuminance images and underwater low-illuminance images are the main research objects.The specific research contents are as follows:The grayscale distribution of images with low illumination characteristics is discussed,and two new enhancement functions are proposed.Using the translation invariance of dyadic wavelets,an enhancement algorithm that can be applied to low illumination images is proposed.The high and low frequency parts generated after the low-illuminance image is decomposed by the dyadic wavelet transform are processed by two new enhancement functions,and then the processed image is subjected to the dyadic wavelet inverse transformation to obtain the target image.From the results of simulation experiments,it can be proved that the low-light images processed by the proposed algorithm are better than other algorithms in both subjective and objective aspects.The characteristics of underwater images are discussed,and using the translation invariance of dyadic wavelets,an enhancement algorithm that can be applied to underwater images is proposed.The low-frequency part generated by the decomposition of the underwater image by the dyadic wavelet transform,within a certain range,select the appropriate enhancement algorithm for processing,and the processed low-frequency image is weighted and fused;The generated high-frequency part is processed by a new enhancement function.In order to ensure that the noise in the high-frequency part is not missed,median filtering is used to reduce noise,and the processed high and low frequency parts are subjected to dyadic wavelet inverse transformation to obtain the image.There is a problem of color distortion and low brightness.Color correction is carried out on this,and the target image can be obtained.Simulation experiments have proved that the underwater images processed by this algorithm are better than other algorithms in both subjective and objective aspects.