[Digikam-users] re JPEG lossiness, PNG

[Andrew Goodbody]

On 21/01/12 15:25, Peter Mc Donough wrote:
>> OK, not listed, but it may work anyway. Did you try it? If it did not
>> work did you provide sample files to Dave Coffin for him to implement
>> the support?
>
> No, I didn't. When I bought the camera, at that time I used jpeg - it
> was a special offer and has suited my idea of a DSLR since - there were
> at least three newer Olympus DSLR camera model generations.
> Later I gave RAW a try and browsing the web I couldn't find any demand
> for a RAW profile of my "new" camera, so asking for one especially for
> me seems to be a waste of the "resource" Dave Coffin.

It would not be especially for you. It would be for you and for all the 
other people out there who also looked for support and did not find it 
and then also did nothing. So your failure to send samples to Dave 
Coffin is actually depriving other people. Just because you could find 
no published demand for support does not mean the demand does not exist, 
merely that those that want it have not published about it.
Why not let Dave Coffin be the judge of what is a waste of his time?

> In fact, Digikam could read the original raw file and I didn't notice
> any problems. On the other hand, I don't know enough about RAW files for
> deciding what, if anything, was missing or faulty.
>
> What I read in the web was an unhappiness about propriatary RAW formats.
> There may be a good reason for propriatary formats - the obvious one I
> see and don't like is that a user may stick to one brand because his
> valuable photos are of in a certain RAW type.

Sounds like a bogus reason to me. I would question if anyone thought 
that way. Raw formats change even in the same brand from one generation 
of camera to another. The solution is to have software support for both 
old and new format. Lots of bigger reasons for sticking to one brand eg 
investment in lenses and other accessories.

> What brough me to Adobe DNG were several discussions, among them:
>
> http://mansurovs.com/dng-vs-raw

Interesting article. I had not noticed the reduction in the size of DNG 
files in comparison to raw files from the camera. I wonder why that is. 
One possibility is that a PC has the computing resources to be able to 
do a better compression than the camera processor. So that would not be 
a feature of DNG per se, merely the recompression of the data with more 
resources available to do it. I wonder how the file size of those 
cameras that produce DNG natively compares.
Unfortunately the article is not clear about issues such as the reduced 
size does not apply if you opt to embed the original raw file, quite the 
reverse in fact. Also manufacturer developing programs can write to 
their own raw file format so you do not necessarily have sidecar files. 
Also it is likely that open source will, in time, gain the ability to 
write to other raw formats (I think it can already write to some but not 
all). Some of the advantages and disadvantages depend on the particular 
software in use and do not really apply in practice.

> The version I have, DNGConverter 6.5, runs under standard Wine in
> Opensuse 11.4 64bit and of course in virtualized Windows XP.

digikam, darktable, rawtherapee, dcraw, ufraw etc all run natively in 
Linux. BTW digikam can do the conversion from camera raw to DNG.

> I am very pro open standards and when I buy my next camera I will check
> before whether its RAW format is supported under Linux.
>
> Peter

I also am very pro open standards and would prefer all cameras to 
produce raw files in a truly open standard format. Unfortunately even 
DNG is not truly open. While Adobe have published the specification 
there is no open process for developing it. DNG is owned and controlled 
by Adobe.

Andrew