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Re: [OM] Using FL-50R, wedding sample pictures, Eneloop batts, etc...

Subject: Re: [OM] Using FL-50R, wedding sample pictures, Eneloop batts, etc...
From: Moose <olymoose@xxxxxxxxx>
Date: Fri, 10 Jul 2009 14:16:07 -0700
Ken Norton wrote:
>> Sounds highly unlikely to me.  Do you have a reliable source for your 
>> statement that ACR uses DCRAW?
>>     
>
> This has been circulating around on the Internet and I think it has to do 
> with one on-line review that the reviewer made a poor assumption about it. It 
> doesn't even make sense, as Adobe owns converter technologies that predate 
> DCRAW by quite some time and also bought out probably the finest raw 
> converter made to make sure Lightroom wasn't stillborn.
>   

I'm pretty sure that at least early on, ACR did indeed use a part of 
dcraw. Possibly not the case more recently.

There's some confusion about the use of dcraw in other products. As I 
understand it, dcraw has three basic parts.

1. Magic decoder rings to extract the RAW data from the camera files and 
put it in a standard format. Remember, many RAW files are losslessly 
compressed and makers are free to use whatever coding and compression 
scheme they choose.

2. Demosaicing algorithms to interpolate Bayer mosaic color data into 
individual RGB data channels for each sensor site.

3. Algorithms to manipulate the RGB data for gamma, color space, 
highlight recovery, etc.

Since Dave posts the source and gives free license to use it, developers 
are free to pick and choose what parts of his code to use, alter or replace.

Some folks have simply put GUI faces on the otherwise command line only 
dcraw. Others, like RawTherapee, use only the decoder rings, and roll 
their own from there. It's a solution that makes a lot of sense, and, I 
believe, how dcraw was, maybe still is(?) used by ACR for some cameras. 
Especially useful for those, like me, that use RAW files not supported 
by the camera makers or ACR, like the CHDK versions from Canons.

The major makers used to provide Software Development Kits, libraries of 
compiled routines and the calls to use them, for those who wanted to 
work with their RAW files. I haven't kept up, but they may still do so. 
I assume apps like ACR might use at least the decoder rings from those 
SDK that are available. Canon, for one, even offers Winders add-ons that 
allow viewing thumbnails for their RAW files in Explorer. Quite useful.

Moose

Moose


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