The PNG format has two flavors: PNG-8 and PNG-24.
PNG-8 is a slightly nicer form of GIF, without the patent implications and with a few additional goodies. It allows you to create a palette of 256 colors out of the millions in the 24-bit color “space”, one or more of which may be designated as fully transparent, and use them to describe a picture.
PNG-24 is actually a misnomer – it’s more like PNG-32. PNG-24 has 24 bits of color (8 per primary) for each pixel, plus another 8 bits for an alpha (transparency) mask. Each pixel may be one of millions of different colors, at 256 different levels of opacity. This allows the PNG-24 format to have soft shadows that don’t obscure what’s beneath them, or to create hazy semi-opaque effects such as those in your example site.
The old Millions vs. Thousands battle was over quite a few years ago, the creakiest old equipment that you will see in use today has at minimum the ability to display 24-bit color, the only variations you will see now are with overall pixel dimensions and additional hoohah to do rapid animations on the fly.
In Freeway, there is a thousands/millions preference in the Document Setup, but that has to do with how “nice” of a preview image Freeway will store within the Freeway document itself (for your convenience, never published except under duress). Millions in this particular case makes for a larger file/better looking/potentially slower experience for YOU, it has no bearing at all on the visitor to your site.
What you may have heard regarding PNG-24 and lesser (cough, IE) browsers is the fact that IE < 8 doesn’t deal well with transparency in PNG images. Freeway has a built-in mechanism for dealing with this, and it properly puts all the burden of fixing things on the bad browser, by requiring JavaScript and an HTC filter to put things right. At the very worst case, the image will display, but any transparent areas will render as a pale gray, and any semi-transparent areas will simply render as opaque.
Walter
On Jan 27, 2009, at 8:54 AM, wingnut wrote:
By setting PNG to millions will that affect who can view the page? I know most people have millions of colours these days but I still tend to use thousands just in case!
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