# 图像滤波

## App

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

## 函数

 `fspecial` 创建预定义的二维滤波器 `fspecial3` Create predefined 3-D filter `convmtx2` 2-D convolution matrix
 `imfilter` 多维图像的 N 维滤波 `roifilt2` Filter region of interest (ROI) in image `nlfilter` General sliding-neighborhood operations `imgaussfilt` 图像的二维高斯滤波 `imgaussfilt3` 3-D Gaussian filtering of 3-D images `wiener2` 二维自适应去噪滤波 `medfilt2` 二维中位数滤波 `medfilt3` 3-D median filtering `modefilt` 2-D and 3-D mode filtering `ordfilt2` 2-D order-statistic filtering `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 Gabor 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
 `freqspace` 频率响应的频率间距 `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

## 主题

### 去噪滤波

• 去除噪声
噪声是指在图像采集或传输过程中出现的像素值的随机误差。去除噪声可以提高图像质量。
• 将高斯平滑滤波器应用于图像
此示例说明如何使用不同强度的高斯平滑滤波器来对图像进行模糊处理。该示例包括各向同性和各向异性高斯滤波。
• Reduce Noise in Image Gradients
This example shows how to reduce noise associated with computing image gradients.

### 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
This example shows how to smooth an image by different amounts by applying box filters of varying sizes to the integral image.