Digikam image re-compression - is it reliable?

[Amos Shapira]

(Sorry was meant to reply to the list as well)

Thanks Nadav. I'll try the %90 and %95 option.
Trouble is that I need to hand the disk-on-key over to the courier in a
couple of hours so might just stick to un-recompressed if it still fits.


> On 20 June 2012 16:37, Nadav Har'El <nyh at math.technion.ac.il> wrote:
>
>> 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,
>> nyh at math.technion.ac.il
>> |-----------------------------------------
>> Phone +972-523-790466, ICQ 13349191 |A fine is a tax for doing wrong. A
>> tax is
>> http://nadav.harel.org.il           |a fine for doing well.
>>
>
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