27 research outputs found
Survey on wavelet based image fusion techniques
Image fusion is the process of combining multiple images into a single image without distortion or loss of information. The techniques related to image fusion are broadly classified as spatial and transform domain methods. In which, the transform domain based wavelet fusion techniques are widely used in different domains like medical, space and military for the fusion of multimodality or multi-focus images. In this paper, an overview of different wavelet transform based methods and its applications for image fusion are discussed and analysed
End-to-End Learning for Simultaneously Generating Decision Map and Multi-Focus Image Fusion Result
The general aim of multi-focus image fusion is to gather focused regions of
different images to generate a unique all-in-focus fused image. Deep learning
based methods become the mainstream of image fusion by virtue of its powerful
feature representation ability. However, most of the existing deep learning
structures failed to balance fusion quality and end-to-end implementation
convenience. End-to-end decoder design often leads to unrealistic result
because of its non-linear mapping mechanism. On the other hand, generating an
intermediate decision map achieves better quality for the fused image, but
relies on the rectification with empirical post-processing parameter choices.
In this work, to handle the requirements of both output image quality and
comprehensive simplicity of structure implementation, we propose a cascade
network to simultaneously generate decision map and fused result with an
end-to-end training procedure. It avoids the dependence on empirical
post-processing methods in the inference stage. To improve the fusion quality,
we introduce a gradient aware loss function to preserve gradient information in
output fused image. In addition, we design a decision calibration strategy to
decrease the time consumption in the application of multiple images fusion.
Extensive experiments are conducted to compare with 19 different
state-of-the-art multi-focus image fusion structures with 6 assessment metrics.
The results prove that our designed structure can generally ameliorate the
output fused image quality, while implementation efficiency increases over 30\%
for multiple images fusion.Comment: repor
An Improved Infrared/Visible Fusion for Astronomical Images
An undecimated dual tree complex wavelet transform (UDTCWT) based fusion scheme for astronomical visible/IR images is developed. The UDTCWT reduces noise effects and improves object classification due to its inherited shift invariance property. Local standard deviation and distance transforms are used to extract useful information (especially small objects). Simulation results compared with the state-of-the-art fusion techniques illustrate the superiority of proposed scheme in terms of accuracy for most of the cases
Generation and Recombination for Multifocus Image Fusion with Free Number of Inputs
Multifocus image fusion is an effective way to overcome the limitation of
optical lenses. Many existing methods obtain fused results by generating
decision maps. However, such methods often assume that the focused areas of the
two source images are complementary, making it impossible to achieve
simultaneous fusion of multiple images. Additionally, the existing methods
ignore the impact of hard pixels on fusion performance, limiting the visual
quality improvement of fusion image. To address these issues, a combining
generation and recombination model, termed as GRFusion, is proposed. In
GRFusion, focus property detection of each source image can be implemented
independently, enabling simultaneous fusion of multiple source images and
avoiding information loss caused by alternating fusion. This makes GRFusion
free from the number of inputs. To distinguish the hard pixels from the source
images, we achieve the determination of hard pixels by considering the
inconsistency among the detection results of focus areas in source images.
Furthermore, a multi-directional gradient embedding method for generating full
focus images is proposed. Subsequently, a hard-pixel-guided recombination
mechanism for constructing fused result is devised, effectively integrating the
complementary advantages of feature reconstruction-based method and focused
pixel recombination-based method. Extensive experimental results demonstrate
the effectiveness and the superiority of the proposed method.The source code
will be released on https://github.com/xxx/xxx
Signal processing algorithms for enhanced image fusion performance and assessment
The dissertation presents several signal processing algorithms for image fusion in noisy multimodal
conditions. It introduces a novel image fusion method which performs well for image
sets heavily corrupted by noise. As opposed to current image fusion schemes, the method has
no requirements for a priori knowledge of the noise component. The image is decomposed with
Chebyshev polynomials (CP) being used as basis functions to perform fusion at feature level. The
properties of CP, namely fast convergence and smooth approximation, renders it ideal for heuristic
and indiscriminate denoising fusion tasks. Quantitative evaluation using objective fusion assessment
methods show favourable performance of the proposed scheme compared to previous efforts
on image fusion, notably in heavily corrupted images.
The approach is further improved by incorporating the advantages of CP with a state-of-the-art
fusion technique named independent component analysis (ICA), for joint-fusion processing
based on region saliency. Whilst CP fusion is robust under severe noise conditions, it is prone to
eliminating high frequency information of the images involved, thereby limiting image sharpness.
Fusion using ICA, on the other hand, performs well in transferring edges and other salient features
of the input images into the composite output. The combination of both methods, coupled with
several mathematical morphological operations in an algorithm fusion framework, is considered a
viable solution. Again, according to the quantitative metrics the results of our proposed approach
are very encouraging as far as joint fusion and denoising are concerned.
Another focus of this dissertation is on a novel metric for image fusion evaluation that is based
on texture. The conservation of background textural details is considered important in many fusion
applications as they help define the image depth and structure, which may prove crucial in
many surveillance and remote sensing applications. Our work aims to evaluate the performance of image fusion algorithms based on their ability to retain textural details from the fusion process.
This is done by utilising the gray-level co-occurrence matrix (GLCM) model to extract second-order
statistical features for the derivation of an image textural measure, which is then used to
replace the edge-based calculations in an objective-based fusion metric. Performance evaluation
on established fusion methods verifies that the proposed metric is viable, especially for multimodal
scenarios