In the field of digital image processing, image fusion technology has gradually become the key. This technology allows us to extract important information from multiple images and merge them into a single, more informative image. Through image fusion, the final image not only reduces the amount of data, but also improves understandability and accuracy. With the development of more and more space detectors and multi-sensors, image fusion technology is becoming more and more important in various applications.
The purpose of image fusion is not only to reduce the amount of data, but also to construct more appropriate images that can be perceived by humans and machines.
In the field of computer vision, sensor image fusion is the process of integrating relevant information from two or more images into one image. The images produced in this way are often more informative than any single source image, especially in remote sensing applications, where the integration of information helps us obtain a more accurate description of the scene.
As the demand for multi-sensor data fusion increases in various application cases, the challenges faced by image processing become increasingly prominent. In many cases, we want to obtain a single image with both high spatial resolution and hyperspectral information, which is particularly important in remote sensing. However, existing instruments are often unable to provide this type of information at the same time due to design or observation limitations, so image fusion technology has become one of the solutions.
Image fusion methods can be roughly divided into two categories: spatial domain fusion and transform domain fusion. Among them, pixel method, Brovey method, principal component analysis (PCA) and IHS-based method belong to the spatial domain technology. High-pass filtering technology is also an important spatial domain fusion method. Although spatial domain methods are easy to understand, they often produce spatial distortion when fusing images, which adversely affects subsequent processing (such as classification problems).
Multiple analytical analysis by frequency domain method has become an effective tool in remote sensing image analysis, among which discrete wavelet transform technology has received special attention.
In the process of image fusion, the input images need to be registered first, because misalignment is the main source of error in image fusion. Known image fusion methods also include high-pass filtering technology, fusion based on IHS transform, fusion based on wavelet transform, etc.
Multi-focus image fusion is used to gather useful information from input images at different focal depths to create an output image that ideally contains all input image information. In visual sensor networks, sensors are often cameras that capture images and video sequences. Due to the limited focal length of the camera's optical lens, only objects within the focal length will be clearly visible, while the rest will be blurred. In order to effectively capture images with different focal length depths in the scene, multi-focus image fusion is particularly important.
Image fusion has many application fields in remote sensing, one of the more important is multi-resolution image fusion (referred to as pan-sharpening). Satellite images are mainly divided into two categories: panchromatic images and multispectral images. Panchromatic images are usually presented in black and white and provide the highest resolution, while multispectral images are captured in different spectral ranges and have reduced resolution. The goal of image fusion is to combine these two types of images to generate a high-resolution multispectral image.
Image fusion is becoming increasingly popular in medical diagnosis and treatment. This technology is often used to register and superimpose multiple patient images to provide more diagnostic information. These fused images can come from multiple images from the same imaging device, or they can combine image data from different technologies, such as MRI, CT, PET, and SPECT. This allows radiologists to more accurately diagnose and treat disease, especially cancer.
With the advancement of science and technology, the development of image fusion technology continues to promote progress in various fields. When we combine multiple images, can we fully unearth the valuable information hidden behind the images?