I tried the **texturetool** in Xcode to compress a bunch of .png textures for use in a SceneKit scene. Tried several options as per [Apple docs](https://developer.apple.com/library/content/documentation/3DDrawing/Conceptual/OpenGLES_ProgrammingGuide/TextureTool/TextureTool.html#//apple_ref/doc/uid/TP40008793-CH108-SW1).

```
  texturetool -e PVRTC --channel-weighting-linear --bits-per-pixel-4 -o ImageL4.pvrtc Image.png

```

The resulting image was 3 to 4 times the size of the original png. I expected it to be significantly smaller. These are square textures, power of 2 etc. Ended up making it smaller and doing a lossy optimization pass. 

What is the right approach to texture compression (for iOS10)?

Updated with compression test results. With this image it was approx. 2x the size. Not surprisingly, the results were the same with textureTool. The PVRTexTool (from Imagination Technologies) offered a wider variety of formats to choose from.

[![PVRTests](https://i.stack.imgur.com/mt62a.png)](https://i.stack.imgur.com/mt62a.png)