Correct way to use png/jpg in OpenGL ES

What is the correct way to save images in png format, if I want to use it in my Android OpenGL 开发者_StackOverflow中文版ES application as texture?

Somehow some textures work, and some texture get incorrect vertex mapping. The code is the same, the image is different.

---

That looks like you're loading the texture data the wrong way, a PNG can be 24-bit per pixel (RGB), or 32-bit per pixel (RGBA). If you don't consider this in the texture loading code, some textures will look like that.