The PNG Guide is an eBook based on Greg Roelofs' book, originally published by O'Reilly.

blaxxun Contact

blaxxun's Contact browser (the unified, version 4.0 name for the older CC3D and CCpro browsers) is available only for the Windows 9x/NT platform and is optimized primarily for performance, like WorldView. Unlike WorldView, however, CC3D also comes in an OpenGL version, and both that and the Direct3D version can support full alpha blending of PNG textures, at least in some modes. The Direct3D modes that support only screendoor transparency also support only 8-bit, palette-based rendering, however.

Because the selection of PC video cards with good, hardware-assisted OpenGL support was still fairly sparse in 1998, only the Direct3D version of Contact 4.002 was tested. It did not support transparency in RGBA-palette PNGs at all, regardless of the material transparency, and gray palette-based PNG textures with transparency failed to inherit the underlying material color. On the other hand, palette and grayscale textures with binary (or single-shade) transparency additionally inherited the underlying material transparency. Implementation problems were also probably to blame for the incorrect rendering of overlapping transparent textures.

Unlike older versions of the browser, which failed to render large textures at all, Contact 4.0 appeared to resample them to smaller sizes if the hardware had insufficient texture memory. In High Quality software-rendering mode, the newer release appeared not to have any size limitations--indeed, its rendering of large, opaque textures was distinctly better than that of Cosmo Player, which is otherwise considered to have a very high quality renderer. On the other hand, transparent textures reverted to stippled transparency in this mode. Contact 4.0 is available for download from

Last Update: 2010-Nov-26