Re: FN-FORUM: png compression

date posted 27th July 2005 16:42

> I had thought that pngs would compress quite small, but my 4k jpg (8%
> compression) is a 41k png when fully compressed.
>
> so apparantly pngs arn't much use for photos, or am I missing something?

PNG is either palletted (PNG-8) or full-colour (PNG-24), roughly mimiking
GIF and JPG respectively. PNG-24 however uses lossless compression as
well as an alpha channel for variable transparency, which is why the file
sizes are quite a bit larger. JPG uses lossy compression, so you lose some
detail and gain some noise.

So for websites JPG is probably best for most photos, but if you need
semi-transparent pixels or lossless compression PNG-24 is what you need.

Anthony
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