# Edge Aware Filter

Edge-aware filtering can remove texture while preserving edges. Some image editing applications use a “surface blur” tool to do this. However, surface blur is a poor substitute for a true edge-aware filter. By using the true edge-aware filter in Astra Image, you can remove texture, and, with the addition of a guide image, you can do other processing too, like flash / no-flash denoising.

<div align="left"><figure><img src="/files/Jel5kZnZU4RxCiiZInLd" alt="The Edge Aware Filter tool."><figcaption><p>The Edge Aware Filter tool.</p></figcaption></figure></div>

**Guide Image**

One of the key features of an edge-aware filter is that you can use a guide image. For example, please imagine that you took two pictures in a dark environment, one with the camera flash on, and one with the camera flash off. The image with the flash off has more details and looks more natural, but it is noisy because of lack of light. If you use the flash image as a guide image in an edge aware filter, you can very effectively denoise the no-flash image while keeping all the details and natural colors. You can also use a guide image to refine a segmentation mask.

**Use original image**\
If you don’t have a guide image, or if you don’t want to use one, select this option.

**Use another image**\
If you have a guide image that you want to use, select this option then click the Browse… button to load it. It must be the same size as the original image.

**Settings**

This group has the settings for the filter.

**Spatial sigma and Color sigma**\
These parameters are very interdependent. They control the overall filtering amount and strength.

**Iterations**\
The number of iterations that the filter will perform. Two or three iterations are usually enough.


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