PNGU is a library for Wii and GameCube that 'wraps' the famous libpng and facilitate png handling and conversions to the native Wii/GC formats. The PNG format has some properties which make it interesting: A background color, a list of transparent colors, alpha channel, it doesn't modify the colors (as jpeg does when compression), open format. The source code of the library is included in the download package.
Features
- It's based in libpng 1.2.29
- Handles images of 8 and 16 bits per channel.
- Handles images in RGB, RGBA, grayscale and grayscale + alpha formats.
- Reads image dimensions, pixel format, background color and transparent colors list.
- Converts images to YCbYCr, linear RGB565, linear RGBA8, 4x4 RGB565, 4x4 RGB5A3 and 4x4 RGBA8 formats.
- Saves YCbYCr images in png RGB8 format.
- Handles images stored in memory or in devoptab devices (SD, Gecko SD, etc...).
- It's ready to be used in multithreaded applications.
Limitations
- Image width and height should be a multiple of 4 (when converting to 4x4 textures)
- Doesn't handle images of 1, 2 or 4 bits per channel.
- Doesn't handle paletized images.
- Endianness problems when using it on a little endian machine (x86 for example) no problems on the Wii/GC.
by Frontier.