---
title: kCGImageSourceThumbnailMaxPixelSize
framework: imageio
role: symbol
role_heading: Global Variable
path: imageio/kcgimagesourcethumbnailmaxpixelsize
---

# kCGImageSourceThumbnailMaxPixelSize

The maximum width and height of a thumbnail image, specified in pixels.

## Declaration

```swift
let kCGImageSourceThumbnailMaxPixelSize: CFString
```

## Discussion

Discussion If this key is not specified, the width and height of a thumbnail is not limited and thumbnails may be as big as the image itself. If present, this key must be a CFNumber value. This key can be provided in the options dictionary that you pass to the function CGImageSourceCreateThumbnailAtIndex(_:_:_:).

## See Also

### Specifying the Read Options

- [kCGImageSourceTypeIdentifierHint](imageio/kcgimagesourcetypeidentifierhint.md)
- [kCGImageSourceShouldAllowFloat](imageio/kcgimagesourceshouldallowfloat.md)
- [kCGImageSourceShouldCache](imageio/kcgimagesourceshouldcache.md)
- [kCGImageSourceShouldCacheImmediately](imageio/kcgimagesourceshouldcacheimmediately.md)
- [kCGImageSourceCreateThumbnailFromImageIfAbsent](imageio/kcgimagesourcecreatethumbnailfromimageifabsent.md)
- [kCGImageSourceCreateThumbnailFromImageAlways](imageio/kcgimagesourcecreatethumbnailfromimagealways.md)
- [kCGImageSourceCreateThumbnailWithTransform](imageio/kcgimagesourcecreatethumbnailwithtransform.md)
- [kCGImageSourceSubsampleFactor](imageio/kcgimagesourcesubsamplefactor.md)