# 图像滤波

## App

 图像区域分析器 Browse and filter connected components in image

## 函数

 `imfilter` 多维图像的 N 维滤波 `roifilt2` Filter region of interest (ROI) in grayscale image `nlfilter` General sliding-neighborhood operations `imgaussfilt` 图像的二维高斯滤波 `imgaussfilt3` 三维图像的三维高斯滤波 `wiener2` 二维自适应去噪滤波 `medfilt2` 二维中位数滤波 `medfilt3` 三维中位数滤波 `modefilt` 2-D and 3-D mode filtering (自 R2020a 起) `ordfilt2` 二维顺序统计量滤波 `stdfilt` Local standard deviation of image `rangefilt` Local range of image `entropyfilt` Local entropy of grayscale image `imboxfilt` 2-D box filtering of images `imboxfilt3` 3-D box filtering of 3-D images `fibermetric` Enhance elongated or tubular structures in image using Frangi vesselness filter `maxhessiannorm` Maximum of Frobenius norm of Hessian of matrix `padarray` 填充数组
 `imbilatfilt` Bilateral filtering of images with Gaussian kernels `imdiffuseest` Estimate parameters for anisotropic diffusion filtering `imdiffusefilt` Anisotropic diffusion filtering of images `imguidedfilter` Guided filtering of images `imnlmfilt` Non-local means filtering of image `burstinterpolant` Create high-resolution image from set of low-resolution burst mode images
 `gabor` Create Gabor filter or Gabor filter bank `imgaborfilt` 将加博滤波器或滤波器组应用于二维图像
 `bwareafilt` 按大小从二值图像中提取对象 `bwpropfilt` Extract objects from binary image using properties
 `integralImage` Calculate 2-D integral image `integralImage3` Calculate 3-D integral image `integralBoxFilter` 2-D box filtering of integral images `integralBoxFilter3` 3-D box filtering of 3-D integral images
 `fspecial` 创建预定义的二维滤波器 `fspecial3` Create predefined 3-D filter `convmtx2` 2-D convolution matrix `freqz2` 2-D frequency response `fsamp2` 2-D FIR filter using frequency sampling `ftrans2` 2-D FIR filter using frequency transformation `fwind1` 2-D FIR filter using 1-D window method `fwind2` 2-D FIR filter using 2-D window method `freqspace` 频率响应的频率间距

## 主题

### 去噪滤波

• 去除噪声
使用平均值滤波、中位数滤波和基于图像局部方差的自适应滤波等方法来去除图像噪声。
• 将高斯平滑滤波器应用于图像
通过使用不同强度的各向同性和各向异性高斯平滑滤波器模糊图像来降低图像噪声。
• Reduce Noise in Image Gradients
Reduce noise associated with computing image gradients so that features can be more accurately detected.

### 积分图像域滤波

• Integral Image
Integral images are a quick way to represent images for filtering. In an integral image, the value of each pixel is the summation of the pixels above and to the left of it.
• Apply Multiple Filters to Integral Image
Smooth an image by different amounts by applying box filters of varying sizes to the integral image.