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# edgeMode

The edge mode to use when texture reads stray off the edge of an image.

```
var edgeMode: MPSImageEdgeMode { get set }
```

## Discussion

Most [`MPSKernel`](/documentation/MetalPerformanceShaders/MPSKernel) objects can read off the edge of the source image. This can happen because of a negative offset property, because the  value of `offset + clipRect.size` is larger than the source image or because the filter looks at neighboring pixels, such as a convolution filter.

The default value is [`MPSImageEdgeMode.zero`](/documentation/MetalPerformanceShaders/MPSImageEdgeMode/zero).

> Note:
> For an ``doc://com.apple.metalperformanceshaders/documentation/MetalPerformanceShaders/MPSCNNPoolingAverage`` object, specifying a ``doc://com.apple.metalperformanceshaders/documentation/MetalPerformanceShaders/MPSImageEdgeMode/clamp`` edge mode is interpreted as a “shrink-to-edge” operation, which shrinks the effective filtering window to remain within the source image borders.

---

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