DeepBlueSky Blog

If you've ever used Adobe Fireworks then you'll know it's image optimiser lists "PNG32" as an image type. But what is this and why does Photoshop not provide it as an option?

Screenshot of Fireworks' image export panel

The PNG image format has three types:

PNG8
PNG24
PNG32

If you usually use Photoshop then at this point you may well be thinking "What's this PNG32 thing?". Well basically PNG32 is PNG24 but with support for full alpha transparency. This means you can have varying degrees of transparency for each pixel, whereas GIFs can only have transparency turned on or off for each pixel. Therefore, when placed on complex or ill-matching backgrounds, transparent PNGs will have nice smooth edges.

Yes I know what you're thinking, "But Photoshop can produce alpha transparent PNG images!". I know! It just doesn't present it to you correctly and that's what had me confused.

Image montage showing Adobe Fireworks image optimiser and Photoshop's Save for Web dialog side by side

Being a keen advocate of Adobe Fireworks I have always realised that PNG32 was the only PNG file type to support true colour alpha images. However, if you regualrly use Photoshop then you'll know that "Save for Web" only offers PNG8 or PNG24 file types in the drop down.

As I'm sure most of you know all you do is tick the "transparency" box in "Save for Web" and you get a alpha transparent PNG. But really what this is doing is creating a PNG32 graphic - Photoshop just decides to hide this from you. Strange...

Posted years ago

Tagged as: Fireworks, Photoshop, PNG

6 Comments on this post

said “Thanks” years ago

Always wondered about this.
a said “uh……” years ago

no, its the difference between index transparency and alpha transparency
Roberto said “Adobe Fireworks” years ago

Adobe Fireworks is far better and focused than Photoshop if you only need to produce web graphics.

I am still amazed that most web designers don't use it as first choice for web development.

It's a mystery...
Dom said “fireworks” years ago

Well I'd have to disagree about fireworks being better for web design. It may be easier to spit out slices but as far as layout, design, ease of use etc its leagues ahead. Thats why its more of an industry standard, its just better quality.
Feeb said “Fireworks is better but I use both” years ago

For producing web layouts, mockups and vector imagery, Fireworks is much better than Photoshop. Bear in mind that's what it was made for.

It's so much quicker, and a million times quicker to edit things and produce accurate, pixel-perfect layouts.

However, if you want very complex raster imagery, then obviously you use PS for that.
Trisha said “Thanks” last year

Good explanation.

I did find today, though, the Fireworks saved the image with a smaller file size than the same image in Photoshop. Strange.