View ASTC files in your browser
The texture compression of phones, tablets and Apple's chips. Open an .astc file right here and keep it as PNG. Nothing leaves your device.
Or drop it anywhere on this page
What you'll see
Your file opens at actual size, or shrunk to fit your screen.
- Actual size, or shrunk to fit
- Drag to pan • Pinch or scroll to zoom
- Fullscreen
- Export • Save as PNG or JPEG
About ASTC
Arm and AMD made ASTC, Adaptive Scalable Texture Compression, and the Khronos Group adopted it in 2012. The graphics chips of recent Android phones, iPhones, iPads, Macs with Apple's chips and the Nintendo Switch decode it, and Unity and Unreal ship games' textures to them in it.
An .astc file is the one Arm's astcenc writes: 16 bytes naming the block size and the picture's size, then the blocks. Every block takes 16 bytes whatever its size, so 4 × 4 blocks keep 8 bits a pixel and 12 × 12 under 1, and each block picks its own colors, partitions and weights.
No browser shows ASTC. Filepeek decodes it itself, every 2D block size from 4 × 4 to 12 × 12, with its own decoder that follows Khronos's spec, and Export saves it as PNG or JPEG. ASTC inside KTX and KTX2 opens the same way.
Adaptive Scalable Texture Compression
.astc
Format
- MIME type
- image/astc
- Made by
- Arm and AMD
- Released
- 2012
Inside the file
- Header
- 16 bytes, then the blocks
- Blocks
- 4 × 4 to 12 × 12, 16 bytes each
- Bits a pixel
- 8 down to 0.89
- Written by
- Arm's astcenc
Opens in every browser
Filepeek decodes ASTC in Chrome, Edge, Firefox and Safari. No browser shows an .astc file by itself.
- YouChromeOpens through Filepeek
- YouEdgeOpens through Filepeek
- YouFirefoxOpens through Filepeek
- YouSafariOpens through Filepeek
Apps that open ASTC
- WindowsArm's astcenc turns it back into PNG • PVRTexTool views it
- Macastcenc and PVRTexTool, as on Windows
- iPhone and iPadNo app opens the file • Games keep their textures in it
- AndroidNo app opens the file • Games load it themselves
Questions
Why won't my image apps open .astc files?
An .astc file holds blocks the way a graphics chip reads them, not a picture, so only texture tools read it. Filepeek turns it into pixels you can save as PNG.
What do the block sizes mean?
Every block takes 16 bytes, so a bigger block spreads them over more pixels: 4 × 4 keeps fine detail at 8 bits a pixel, while 8 × 8 takes 2 and 12 × 12 under 1, with blurrier detail. The bar names the size a file uses.
Why are some blocks bright magenta?
Magenta is the error color ASTC's spec gives blocks a decoder can't read: damaged ones, or HDR ones, which Filepeek shows that way.
How do I convert ASTC to PNG?
Open it, then choose Export and Save as PNG or JPEG.