How do I save a PNG file with an alpha channel in Photoshop CS5?

[Guest]

I have a PNG file created in Photoshop and I need to save it with an alpha channel for web purposes. I tried 'Save for Web & Devices' and selecting the Transparent box. Then, after saving, when I select 'get info' for the file it says there is no alpha channel. I'm stumped I can't seem to create an alpha channel from within Photoshop while I'm editing. Help!

[Willi Adelberger · Accepted solution]

PNG does not support alpha channels, only alpha transparency when you save it as PNG24. If you need to have Alpha channels in Photoshop you have to save as PSD.

[Guest]

Thanks very much! All sorted

[nad33m]

If you save as a 24bit png with transparent checked photoshop will save the png with transparent background (ie alpha transparency).  The png will appear transparent in a web browser.

[Philip25697023ry6h]

For anyone stumbling across this high-pagerank answer when trying (in vain) to get Photoshop to correctly save alpha channels in PNG files, there is a great open-source plugin that allows for reading and writing of PNG alpha as either transparency OR alpha channels.