Digikam image re-compression - is it reliable?

[Nadav Har'El]

On Wed, Jun 20, 2012, Amos Shapira wrote about "Re: Digikam image re-compression - is it reliable?":
> They are in JPG, not RAW. exif is copied over.
> Minimal compression setting (whatever that means on the camera's user
> interface).

It is possible that the "minimal compression" option exists not because
it is recommended, but because the marketing people demanded it, and
you're actually supposed to use the better compressed options named
something like "fine" or "normal" or something.

Just as an example of what you might be wasting, I took a 12 megapixel
(3000x4000) family photo, and saw the following sizes:

	8.9 MB - lossless compression (PNG)
	4.2 MB - JPEG at 100% setting
	3.5 MB - JPEG at 99% setting
	2.4 MB - JPEG at 95% setting
	1.8 MB - JPEG at 90% setting
	1.4 MB - JPEG at 85% setting
	1.1 MB - JPEG at 80% setting
	0.8 MB - JPEG at 75% setting

So as you can see, you can indeed significantly reduce your file size by
not insisting on "minimal compression" (if that means lossless
compression, or JPEG at 100% or 99% setting) you can achieve a much
better compression. I'd go with 95% or even 90% and don't think you'll
ever notice a difference (though I don't presume to be an expert on the
subject). I wouldn't go down to 75% unless you're really short on space-
remember that in 10 years, you'd be laughing at these sizes which you
once thought were large ;-)

Nadav.

-- 
Nadav Har'El                        |                 Wednesday, Jun 20 2012, 
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