Multifocus image fusion scheme based on feature contrast in the lifting stationary wavelet domain

Huafeng Li,Yi Chai,Shanbi Wei

doi:10.1186/1687-6180-2012-39

Huafeng Li, Yi Chai + Show 1 more

Open Access

https://doi.org/10.1186/1687-6180-2012-39

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Abstract

Abstract For fusion of multifocus images, a novel image fusion method based on multiscale products in lifting stationary wavelet (LSWT) domain is proposed in this article. In order to avoid the influence of noise and select the coefficients of the fused image properly, different subband coefficients employ different selection principles. For choosing the low frequency subband coefficients, a new modified energy of Laplacian (EOL) is proposed and used as the focus measure to select the coefficients from the clear parts of the low frequency subband images; when choosing the high frequency subband coefficients, a novel feature contrast measurement of the multiscale products is proposed, which is proved to be more suitable for fusion of multifocus images than the traditional contrast measurement, and used to select coefficients from the sharpness parts of the high frequency subbands. Experimental results demonstrate that the proposed fusion approach outperforms the traditional discrete wavelet transform (DWT)-based, LSWT-based and LSWT-traditional-contrast-(LSWT-Tra-Con)-based image fusion methods, even though the source images are corrupted by a Gaussian noise, in terms of both visual quality and objective evaluation.

Highlights

In applications of digital cameras, when a lens focuses on a subject at a certain distance, all subjects at that distance are sharply focused
The proposed image fusion algorithm is compared with discrete wavelet transform (DWT)-simplebased method (Method 1), lifting stationary wavelet transform (LSWT)-simple-based method (Method 2), and nonsubsampled contourlet transform (NSCT)-simple-based method (Method 3), in all of which the low frequency subband coefficients and the high frequency subband coefficients are merged by the ‘averaging’ scheme and the ‘Coefabs-max’ scheme, respectively
In Method 7, the NSCT is used as the multiscale transforms (MST) method, and our proposed ‘improved EOL (IEOL)-max’ and ‘multiscale products (MSP)-con-max’ are, respectively, employed to fuse the low and high frequency subbands coefficients (We name it as ‘NSCT-MSP-Con’)

Summary

Introduction

In applications of digital cameras, when a lens focuses on a subject at a certain distance, all subjects at that distance are sharply focused. To make up for the aforementioned deficiencies of the traditional MST-based image fusion methods, we present a new multifocus image fusion scheme which incorporates the merits of interscale dependencies into the image fusion field In this method, after decomposing the original images using the LSWT, we use a new modified energy of Laplacian, which can reflect features of the edges of the low frequency subimage in LSWT domain, as the focus measure to select the coefficients of the fused image; when choosing the high frequency subband coefficients, a novel local neighborhood feature contrast of the multiscale products, which can effectively represent the salient features and sharp boundaries of image, is developed and used as the measurement to select coefficients from the clear parts of source images.

Lifting stationary wavelet transform

Methods

Conclusion