To obtain all-in-focus image, it is important to extract the focus area from local focus images. This paper proposed a multi focus image fusion method to obtain an all-in-focus image. First, the focus areas are extracted using frequency domain transfo...
To obtain all-in-focus image, it is important to extract the focus area from local focus images. This paper proposed a multi focus image fusion method to obtain an all-in-focus image. First, the focus areas are extracted using frequency domain transformation. By using a band-pass filter, noise can be removed and enhanced the detailed parts of the image that local focus area. The edge detection of the focus area was then performed through a Laplacian filter using the secondary differential of the image. The Laplacian filtered image extracts conjunctival goblet cell features shown in the local focus image. The focus area was detected through thresholding because it reacts strongly to the thin lines or isolation points in the Laplacian filtered image. A final focus area was also determined as a morphological operation to expand the focus area. The final focus area produced weights with the guided filter, which preserves the edges, to obtain fused images with no prominent boundaries in image connection. A window-size-updating method is adopted in the guided filter to reduce the number of parameters.
This paper presents a novel algorithm that can operate on a large number of input images (10 or more) and obtain an all-in-focus image. Experimental results demonstrate that this algorithm is robust to noise and capable of preserving local focus information through focal area extraction. It is also relatively simple because processing is carried out through methods such as frequency domain transformation and morphological computation. All-in-focus images can be obtained by using camera taken images as well as microscopic images. It is expected that the proposed method for all-in-focus images will be contributed to the quantitative analysis of the research for conjunctival goblet cells.