[Digikam-users] Digikam internal precision?

[Peter Shute]

Excellent idea. What would be a good type of picture to try it on?  Perhaps one with areas with pixels close in value, to see if they end up with the same value.

________________________________
From: Bartek Pietrasiak [mailto:pietras.sp at gmail.com]
Sent: Friday, 22 January 2010 9:34 AM
To: digiKam - Home Manage your photographs as a professional with the power of open source
Subject: Re: [Digikam-users] Digikam internal precision?



Ok. If you have from the start more informations, you don't want to waste them in the calculations working in 8 bits.
But the point is *also* that you want to lose as less information is possible when you edit any image, since usually we do more than just one operation on our photos.

If for example we do some blurring on a 8 bit image, we get always 256 shades of gray. In some next operation, for example levels adjust, we could reduce it to 200 shades of gray.
But if we convert the same image to 16 bits and then we apply the same blurring, we get 65536 shades of gray, isn't it? If we do some other operations next, we still have a lot of shades to work with, and this could help preserve detail in dark or light areas, no? Even 30000 shades, less than the initial dynamics, are a LOT of informations.

So this could be useful if we do more operations on the images, don't you think?

bye
gerlos


It is funny, that we are talking about that. The advantage of the 16 bits over 8 bits from a 8 bit file when a few operations are performed seems to be logical. I shoot in raw and the raw developers usually work with 16 bits, but I don't care. I've never tried to make some raw developer to work on 8 bits because I've read many times that this is the advantage of raw and I haven't checked this by myself. The white balance is the main reason why I use raw now.
Now, I mean funny, because I've just realized that I also have this feeling and non of us have never checked whether the difference can be spotted on a final picture at all, not on its histogram, which can be easily done ;) So simply, can one of you/us, who made a few operation on some jpgeg, make a test and tell us whether the difference can by spotted and show the example?
When I get some jpges from some friends, family etc.  the only thing which I do is usually is to crop, curves or simply contrast and sharpen, sometimes perspective and/or distortion correction.  I have a feeling that the difference can't be spotted when only those few operations are performed. High time to check this ;)
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