---
title: "astc(blockSize:quality:)"
framework: realitykit
role: symbol
role_heading: Type Method
path: "realitykit/textureresource/compression/astc(blocksize:quality:)"
---

# astc(blockSize:quality:)

Compresses the imported image with ASTC.

## Declaration

```swift
static func astc(blockSize: TextureResource.Compression.ASTCBlockSize, quality: TextureResource.Compression.ASTCQuality = .fast) -> TextureResource.Compression
```

## Discussion

Discussion If the device doesn’t support ASTC pixel formats, RealityKit applies compression as part of the .reality file export. note: Remove an unused alpha channel from the source image to get better compression quality.

## See Also

### Specifying the compression settings

- [default](realitykit/textureresource/compression/default.md)
- [none](realitykit/textureresource/compression/none.md)
- [TextureResource.Compression.ASTCBlockSize](realitykit/textureresource/compression/astcblocksize.md)
- [TextureResource.Compression.ASTCQuality](realitykit/textureresource/compression/astcquality.md)