# guided-filter

**Repository Path**: msnh/guided-filter

## Basic Information

- **Project Name**: guided-filter
- **Description**: Fast and complete guided filter implementation for OpenCV
- **Primary Language**: C++
- **License**: MIT
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 1
- **Created**: 2020-04-21
- **Last Updated**: 2023-09-26

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# Guided filter for OpenCV

Guided filter is an edge-preserving smoothing filter like the bilateral filter. It is straightforward to implement and has linear complexity independent of the kernel size. For more details about this filter see [[Kaiming10]](http://research.microsoft.com/en-us/um/people/kahe/eccv10/).


## Usage

The interface consists of one simple function `guidedFilter` and a class `GuidedFilter`. If you have multiple images to filter with the same guidance image then use `GuidedFilter` class to avoid extra computations on initialization stage. The code supports single-channel and 3-channel (color) guidance images and `CV_8U`, `CV_8S`, `CV_16U`, `CV_16S`, `CV_32S`, `CV_32F` and `CV_64F` data types.


## Examples

These examples are adapted from the [original MATLAB implementation](http://research.microsoft.com/en-us/um/people/kahe/eccv10/guided-filter-code-v1.rar).

### Smoothing

```c++
cv::Mat I = cv::imread("./img_smoothing/cat.bmp", CV_LOAD_IMAGE_GRAYSCALE);
cv::Mat p = I;

int r = 4; // try r=2, 4, or 8
double eps = 0.2 * 0.2; // try eps=0.1^2, 0.2^2, 0.4^2

eps *= 255 * 255;   // Because the intensity range of our images is [0, 255]

cv::Mat q = guidedFilter(I, p, r, eps);
```

[![Cat](http://atilimcetin.com/guided-filter/img_smoothing/cat-small.png)](http://atilimcetin.com/guided-filter/img_smoothing/cat.png)

[![r=2, eps=0.1^2](http://atilimcetin.com/guided-filter/img_smoothing/cat-2-0.1-small.png)](http://atilimcetin.com/guided-filter/img_smoothing/cat-2-0.1.png)
[![r=2, eps=0.2^2](http://atilimcetin.com/guided-filter/img_smoothing/cat-2-0.2-small.png)](http://atilimcetin.com/guided-filter/img_smoothing/cat-2-0.2.png)
[![r=2, eps=0.4^2](http://atilimcetin.com/guided-filter/img_smoothing/cat-2-0.4-small.png)](http://atilimcetin.com/guided-filter/img_smoothing/cat-2-0.4.png)

[![r=4, eps=0.1^2](http://atilimcetin.com/guided-filter/img_smoothing/cat-4-0.1-small.png)](http://atilimcetin.com/guided-filter/img_smoothing/cat-4-0.1.png)
[![r=4, eps=0.2^2](http://atilimcetin.com/guided-filter/img_smoothing/cat-4-0.2-small.png)](http://atilimcetin.com/guided-filter/img_smoothing/cat-4-0.2.png)
[![r=4, eps=0.4^2](http://atilimcetin.com/guided-filter/img_smoothing/cat-4-0.4-small.png)](http://atilimcetin.com/guided-filter/img_smoothing/cat-4-0.4.png)

[![r=8, eps=0.1^2](http://atilimcetin.com/guided-filter/img_smoothing/cat-8-0.1-small.png)](http://atilimcetin.com/guided-filter/img_smoothing/cat-8-0.1.png)
[![r=8, eps=0.2^2](http://atilimcetin.com/guided-filter/img_smoothing/cat-8-0.2-small.png)](http://atilimcetin.com/guided-filter/img_smoothing/cat-8-0.2.png)
[![r=8, eps=0.4^2](http://atilimcetin.com/guided-filter/img_smoothing/cat-8-0.4-small.png)](http://atilimcetin.com/guided-filter/img_smoothing/cat-8-0.4.png)


### Flash/no-flash denoising

```c++
cv::Mat I = cv::imread("./img_flash/cave-flash.bmp", CV_LOAD_IMAGE_COLOR);
cv::Mat p = cv::imread("./img_flash/cave-noflash.bmp", CV_LOAD_IMAGE_COLOR);

int r = 8;
double eps = 0.02 * 0.02;

eps *= 255 * 255;   // Because the intensity range of our images is [0, 255]

cv::Mat q = guidedFilter(I, p, r, eps);
```

[![Cave Flash](http://atilimcetin.com/guided-filter/img_flash/cave-flash-small.png)](http://atilimcetin.com/guided-filter/img_flash/cave-flash.png)
[![Cave No Flash](http://atilimcetin.com/guided-filter/img_flash/cave-noflash-small.png)](http://atilimcetin.com/guided-filter/img_flash/cave-noflash.png)
[![Cave Denoised](http://atilimcetin.com/guided-filter/img_flash/cave-denoised-small.png)](http://atilimcetin.com/guided-filter/img_flash/cave-denoised.png)


### Feathering

```c++
cv::Mat I = cv::imread("./img_feathering/toy.bmp", CV_LOAD_IMAGE_COLOR);
cv::Mat p = cv::imread("./img_feathering/toy-mask.bmp", CV_LOAD_IMAGE_GRAYSCALE);

int r = 60;
double eps = 1e-6;

eps *= 255 * 255;   // Because the intensity range of our images is [0, 255]

cv::Mat q = guidedFilter(I, p, r, eps);
```

[![Mask](http://atilimcetin.com/guided-filter/img_feathering/toy-mask-small.png)](http://atilimcetin.com/guided-filter/img_feathering/toy-mask.png)
[![Guidance](http://atilimcetin.com/guided-filter/img_feathering/toy-small.png)](http://atilimcetin.com/guided-filter/img_feathering/toy.png)
[![Feathering](http://atilimcetin.com/guided-filter/img_feathering/toy-feather-small.png)](http://atilimcetin.com/guided-filter/img_feathering/toy-feather.png)


### Enhancement

```c++
cv::Mat I = cv::imread("./img_enhancement/tulips.bmp", CV_LOAD_IMAGE_COLOR);
I.convertTo(I, CV_32F, 1.0 / 255.0);

cv::Mat p = I;

int r = 16;
double eps = 0.1 * 0.1;

cv::Mat q = guidedFilter(I, p, r, eps);

cv::Mat I_enhanced = (I - q) * 5 + q;
```

[![Tulip](http://atilimcetin.com/guided-filter/img_enhancement/tulips-small.png)](http://atilimcetin.com/guided-filter/img_enhancement/tulips.png)
[![Smoothed](http://atilimcetin.com/guided-filter/img_enhancement/tulips-smoothed-small.png)](http://atilimcetin.com/guided-filter/img_enhancement/tulips-smoothed.png)
[![Enhanced](http://atilimcetin.com/guided-filter/img_enhancement/tulips-enhanced-small.png)](http://atilimcetin.com/guided-filter/img_enhancement/tulips-enhanced.png)


## License

MIT license.