Re: Workflow for Photographers
Re: Workflow for Photographers
- Subject: Re: Workflow for Photographers
- From: Andrew Visscher <email@hidden>
- Date: Sun, 30 Nov 2003 17:13:09 -0500
From: Andrew Rodney <email@hidden>
>
>
on 11/26/03 9:08 AM, email@hidden wrote:
>
>
> What EXIF really needs to
>
> do is simply embed profiles so that any color space can easily
>
be supported.
>
>
Amen to that! I recall reading on another site that there's a
>
group of
>
Japanese camera manufacturers that have their own standards as to
>
how to
>
deal with EXIF and other color issues and it seemed like these
>
guys were not
>
at all interested in evolving to this point.
While you are requesting that they begin to embed an actual profile, why not
ask that they save the JPGs in RGB format rather than sYCC format? My
current understanding of EXIF (according to what Chuck Westfall of Canon has
said elsewhere) is that the in-camera JPGs are saved in sYCC format,
encompassing a huge space, in order to save extended color range.
Supposedly, this extended color information is used by such things as the
Epson PIM plugin when it is used to read those JPGs into Photoshop. However,
when an in-camera sRGB JPG is read straight into Photoshop w/o a plugin to
use that info, those colors outside the sRGB range are truncated to fit the
0-255 range the 8 bit values can hold. Another downside is that this
sYCC->sRGB conversion involves going from that very large space to a small
space, all in 8 bits, causing a good chance of posterization, as is usual in
such cases.
If an in-camera non-RAW file were saved in RGB format to begin with, AND
with a proper profile, it would be much more useful. The compression ratio
may be lower as a result, but the image data ought to be better.
Note: I'm basing the above statements on Chuck Westfall's comments that the
Canon in-camera JPGs are saved in sYCC format, per the EXIF standard, and on
the math involved in converting an sYCC JPG file to RGB data, per the JPG
format documentation. I am not suggesting Chuck said that the RAW files are
in sYCC; I am suggesting he meant the JPGs are. (OK, so I wasn't the first
to think of that... I just seem to have fallen for the idea that it is how
this works.)
- Andy
P.S. Sorry if this ends up getting posted twice... I originally sent it
from my web email access while travelling, which must have marked it as
coming from the wrong email address... so I received a message that this was
a members-only list & that posting would have to wait for moderator
approval. Maybe the moderator will ignore the one from the wrong email
address now...
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