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图像滤波

卷积和相关性、预定义和自定义滤波器、非线性滤波、边缘保持滤波器

滤波是一种用于修正或增强图像的技术。例如,您可以对图像进行滤波以强调某些特征或删除其他特征。用滤波实现的图像处理运算包括平滑、锐化和边缘增强。

App

Image Region AnalyzerBrowse and filter connected components in an image

函数

全部展开

imfilterN-D filtering of multidimensional images
fspecial创建预定义的二维滤波器
fspecial3Create predefined 3-D filter
roifilt2Filter region of interest (ROI) in image
nlfilterGeneral sliding-neighborhood operations
imgaussfilt2-D Gaussian filtering of images
imgaussfilt33-D Gaussian filtering of 3-D images
wiener2二维自适应去噪滤波
medfilt22-D median filtering
medfilt33-D median filtering
ordfilt22-D order-statistic filtering
stdfiltLocal standard deviation of image
rangefiltLocal range of image
entropyfiltLocal entropy of grayscale image
imboxfilt2-D box filtering of images
imboxfilt33-D box filtering of 3-D images
fibermetricEnhance elongated or tubular structures in image
maxhessiannormMaximum of Frobenius norm of Hessian of matrix
convmtx22-D convolution matrix
padarrayPad array
imbilatfiltBilateral filtering of images with Gaussian kernels
imdiffuseestEstimate parameters for anisotropic diffusion filtering
imdiffusefiltAnisotropic diffusion filtering of images
imguidedfilterGuided filtering of images
imnlmfiltNon-local means filtering of image
burstinterpolantCreate high-resolution image from set of low-resolution burst mode images
gaborCreate 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
bwpropfiltExtract objects from binary image using properties
integralImageCalculate 2-D integral image
integralImage3Calculate 3-D integral image
integralBoxFilter2-D box filtering of integral images
integralBoxFilter33-D box filtering of 3-D integral images
freqspace频率响应的频率间距
freqz22-D frequency response
fsamp22-D FIR filter using frequency sampling
ftrans22-D FIR filter using frequency transformation
fwind12-D FIR filter using 1-D window method
fwind22-D FIR filter using 2-D window method

主题

空间域中的图像滤波入门

什么是空间域中的图像滤波?

在经过空间滤波的图像中,每个输出像素的值是相邻输入像素的加权和。权重由称为卷积核或滤波器的矩阵提供。

Filter Grayscale and Truecolor (RGB) Images using imfilter Function

This example shows how to filter an image with a 5-by-5 averaging filter containing equal weights.

Filter Images Using Predefined Filter

This example shows how to create a type of special filter called an unsharp masking filter, which makes edges and detail in an image appear sharper.

imfilter Boundary Padding Options

When a portion of the convolution or correlation kernel extends past the edge of an image, you can extrapolate image values by zero-padding the image or by replicating boundary pixels.

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.

边缘保持滤波

What is Guided Image Filtering?

Guided image filtering performs edge-preserving smoothing on an image. It uses the content of a second image, called a guidance image, to influence the filtering.

Perform Flash/No-flash Denoising with Guided Filter

This example shows how to reduce noise from an image while using a guidance image to preserve the sharpness of edges.

Segment Thermographic Image after Edge-Preserving Filtering

This example shows how to segment a hot object from the background in a thermographic image.

按图像属性滤波

Calculate Properties of Image Regions Using Image Region Analyzer

This example shows how to calculate the properties of regions in binary images by using the Image Region Analyzer app.

Filter Images on Properties Using Image Region Analyzer App

This example shows how to create a new binary image, such as a mask image, by filtering an existing binary image based on properties of regions in the image.

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.

频域滤波

Design Linear Filters in the Frequency Domain

You can design filters that modify the frequency content of images. Filtering in the frequency domain is often faster than filtering in the spatial domain.