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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.

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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 a transparency but they probably said that so people don't submit PNG8.

https://graphicdesign.stackexchange.com/questions/6151/png32-vs-png24-vs-png8

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.

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    PNG-8 supports full alpha channel. 1-color transparency is only Photoshop's limitation. – Kornel Mar 3 '13 at 23:53
  • make that an answer – horatio Mar 5 '13 at 16:41
  • To ImageMagick and Photoshop, PNG-8 means an 8-bit indexed-color PNG that is either opaque or has 1-color transparency. The limitation to 1-color transparency was only imposed so the user could easily specify an image could be handled by Internet Explorer. – Glenn Randers-Pehrson Jan 17 '16 at 0:40

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