We're creating icons for a mobile app, and the developers have asked for very specific files. One needs to be 48px x 48px and has to be a 24-bit PNG with alpha and no transparency. I'm using Fireworks CS3 and I wondered if exporting the PNG as a PNG-24 would handle these requirements as only PNG-8 offers an Index/Alpha or no transparency.
PNG8 is 8-bit and supports a single color index flagged as the transparent color.
PNG24 3 8-bit channels (RGB) color wihtout alpha, and PNG32 is RGB + alpha channel (you need 32 bits to store 4 8-bit channels). The alpha channel is
So IIRC, you want PNG32, and you want to set up an alpha channel for the document, and then set matte color to none or transparent in the export.
I'd set up a simple test item with a solid fill and a circular alpha channel, do your export, and ask the developers to confirm that your result complies with their specification.