Foevon and Red (Again!)

James M Hughes

Senior Member
Messages
1,984
Reaction score
4
Location
London, UK
A couple of weeks back there was a long series of posts regarding the Foevan sensor and its ability (or inability) to capture red properly.

I'm still not sure about this, myself. But one thing does seem clear; it's definitely not easy to process RAW images with strong reds in SPP.

I took this image (SD-14 and 28mm f1.8 lens, 100 ISO and no exposure compensation) of my wife wearing a bright red jacket, and had a lot of trouble processing it in SPP. Basically, the red channel was very strong, and I ended up having to use quite a bit of exposure compensation (around -1.7) in SSP to avoid the red channel clipping. I adjusted the image as best possible in SPP, but still ended up with something that needed tweaking in photoshop afterwards. I find this a lot with SPP - the mid tones always seem to be too light, resulting in washed-out images that look 'thin' and lacking in richness and contrast. It's almost as though there's a slider missing - something that would make the mid tones darker. The fill-light was kept at or near it's centre point, incidentally.
Here's the image as it left SPP



And here's the same image after a bit of work in photoshop.



Still not perfect, perhaps, but a LOT better than the first image. The black skirt looks darker, and the red of the jacket matches the density of its real life colour. Maybe it's my lack of skill with SPP, but I almost always find my images need further work after processing - I can't get what I want in SPP alone, no matter what I do. Does anyone else find this, or am I doing something wrong?
J M Hughes
 
James,

I believe (just my opinion) that the majority of the red-reproduction problem is with SPP's handling of the conversion from X3 raw to the working color space used by SPP. I'm not sure what that color space is exactly, but it seems to be much smaller than is ideal considering the exceptionally large color gamut of the X3 raw data. SPP appears to be throwing a huge amount of color information away before it even applies any adjustments. I'm not sure if it's just an issue with the conversion algorithms, or some fundamental color-processing roadblock that Sigma has encountered, but the situation is certainly less than perfect.

I have written to Sigma on this issue and am waiting on a response from them. I'll keep you posted.

By the way, see the discussion here: http://forums.dpreview.com/forums/readflat.asp?forum=1027&thread=28576411

--
~ J.Porter ~
 
Thanks for the reply and link - God - there's a lot to digest there! But at least it seems others have had similar problems. How I wish I could process my SD-14 RAW mages in Phase One capture One 4!
Best wishes, J M Hughes
 
James,

I believe (just my opinion) that the majority of the red-reproduction
problem is with SPP's handling of the conversion from X3 raw to the
working color space used by SPP. I'm not sure what that color space
is exactly, but it seems to be much smaller than is ideal considering
the exceptionally large color gamut of the X3 raw data. SPP appears
to be throwing a huge amount of color information away before it even
applies any adjustments. I'm not sure if it's just an issue with the
conversion algorithms, or some fundamental color-processing roadblock
that Sigma has encountered, but the situation is certainly less than
perfect.

I have written to Sigma on this issue and am waiting on a response
from them. I'll keep you posted.

By the way, see the discussion here:
http://forums.dpreview.com/forums/readflat.asp?forum=1027&thread=28576411

--
~ J.Porter ~
Yes, when you hear please post back to this thread, even if it is months from now. Many will want to know the answer.
 
They need to invest some cash into a proper raw converter - and are
harming themselves a lot by not doing so. All the endless
megapixel/reds/hi iso/slow SPP debates of the past could have been
adressed or prevented so easily.

O.
Oh, believe me... I'm sure they've invested a very large amount of money into what we currently have. A full color lab doesn't come cheap, nor does the expertise required to do something constructive with it.

It's the next cycle of software development that I'm interested in... to see where they go from here.

--
~ J.Porter ~
 
They need to invest some cash into a proper raw converter - and are
harming themselves a lot by not doing so. All the endless
megapixel/reds/hi iso/slow SPP debates of the past could have been
adressed or prevented so easily.

O.
Oh, believe me... I'm sure they've invested a very large amount of
money into what we currently have. A full color lab doesn't come
cheap, nor does the expertise required to do something constructive
with it.

It's the next cycle of software development that I'm interested in...
to see where they go from here.
In that context it is even more impressive to see how Irident came up with an own approach to Foveon images. I can only say this again, Sigma should license Raw Developer.

Edit: I suspect all that is keeping them from it is paranoia regarding the X3F code.

O.
--
http://www.flickr.com/photos/ollivr/
http://www.flickriver.com/photos/ollivr/popular-interesting/
http://seen.by.spiegel.de/ollivr-1
 
In that context it is even more impressive to see how Irident came up
with an own approach to Foveon images. I can only say this again,
Sigma should license Raw Developer.

Edit: I suspect all that is keeping them from it is paranoia
regarding the X3F code.

O.
I know Iridient uses dcraw for X3F import, but what they do with the linear tiff afterward is very interesting. Apparently the latest version of Raw Developer has improvements for "heavy red saturation"... somebody who has the latest version, please do some testing. I wonder if it's reflective of an improvement in dcraw in this regard, or something separate that Iridient is doing...?

--
~ J.Porter ~
 
Hi James

It is easier to get things adjusted if one exposes the values inside the limits in the first place with histogram. This applies to all bright colors as well. As you say it may need as much as -1.7 correction in camera.

Best
Aaro
--
!!! Sorry, I don't use blurr filter in my camera, film or digital.



http://www.lumisoft.fi/gallery
 
In that context it is even more impressive to see how Irident came up
with an own approach to Foveon images. I can only say this again,
Sigma should license Raw Developer.

Edit: I suspect all that is keeping them from it is paranoia
regarding the X3F code.

O.
I know Iridient uses dcraw for X3F import, but what they do with the
linear tiff afterward is very interesting. Apparently the latest
version of Raw Developer has improvements for "heavy red
saturation"... somebody who has the latest version, please do some
testing. I wonder if it's reflective of an improvement in dcraw in
this regard, or something separate that Iridient is doing...?
Raw Developer has a currently unique conversion routine for x3f files. The most substancial difference can be seen when processing skintones. The overall color palette fits together much better than SPP's. You can get a trial here http://iridientdigital.com/ to form an own opinion. IMO most people would get better results with Raw Developer.

O.
--
http://www.flickr.com/photos/ollivr/
http://www.flickriver.com/photos/ollivr/popular-interesting/
http://seen.by.spiegel.de/ollivr-1
 
I had the opportunity to photograph the lavender fields on the Olympic Peninsula WA yesterday and posted some info about red adjustment this morning.

http://dp1meanderings.blogspot.com/

The reds in my images often seem to need a bit more yellow...they're just too pink. Fortunately this seems to be an easy fix; but, I would expect Sigma to find a way to incorporate it into their raw processor.

Charles Maclauchlan

--
http://dp1meanderings.blogspot.com/
http://bluespix.net
 
Hi James

It is easier to get things adjusted if one exposes the values inside
the limits in the first place with histogram. This applies to all
bright colors as well. As you say it may need as much as -1.7
correction in camera.

Best
Aaro
--
!!! Sorry, I don't use blurr filter in my camera, film or digital.



http://www.lumisoft.fi/gallery
I initially used my SD-14 with -0.7 exposure compensation, but was sometimes getting rather dense shadows. I read some Sigma users advocating +0.7 comp, so I tried that for a while, then set the camera back to 00 thinking it was a good compromise, and that any issues with over-exposure could be fixed afterwards in SPP. I'll try shooting some more pictures at different exposures, to see how they process in SPP afterwards - maybe setting -1 or greater will help.

The Iridient RAW Developer sounds interesting - I'll try downloading the free trial and see how that shapes up!
Thanks to everyone who posted.
Best wishes, J M Hughes
 
............so long as you have an SD9 or (it would seem) SD10 ... they just need to fix the colour issues with the SD14 (Green casts are always Horrible, sony found that out with the F707 and fixed it in the 717) and affect reds too, the pic from the OP has it , he fixed it in the finished image..

I've written to Sigma Japan about it - I doubt it'll help but it's better than doing nothing, if it's not fixed it's goodbye SD14 and I'll be sticking with the SD9..

--
Please ignore the Typos, I'm the world's worst Typist

 
The SD10 photos are not better - see below:

1. SPP 2. X3f 3. X3f/Photoshop



Also, Pavel uses an SD10 too and also complained about reds. But in case your SD14 have a green cast - Just get yourself Lightroom and make your own import calibration preset. It is really easy to do, Lightroom is a charm to work with, nothing crashes/looks weird/gets on your nerve. Also, see how well custom WB works. All this is because it's a software problem, the software cannot deal with the sensor response variation, which the sensor apparently takes care of on its own when using custom WB.

O.
--
http://www.flickr.com/photos/ollivr/
http://www.flickriver.com/photos/ollivr/popular-interesting/
http://seen.by.spiegel.de/ollivr-1
 
Lightroom is a charm to work with, nothing crashes/looks weird/gets
on your nerve.
Well, except that the whole GUI looks childish, some of the scroll bars are on the wrong side, and the entire interface is inexplicably modal, but we mustn't quibble, I suppose.

Lightroom's real merits all come from its underlying Camera Raw technology. If you've got Photoshop, I say stick with Camera Raw and don't hand Adobe extra money for the same technology gummed up in a freak interface with a new name slapped on it.

--
http://www.zenfolio.com/markalanthomas/
 
The first thing I'd try would be to drag down the highlights slider. I know the reds don't at a glance seem like highlights, but the slider sees them that way. The second thing I'd do is try adding a tick or two of Fill Light because it'll not only bring up the areas that are getting too dark, but also bring down the bright end of the exposure — e.g. the reds.

--
http://www.zenfolio.com/markalanthomas/
 
case your SD14 have a green cast - Just get yourself Lightroom and
make your own import calibration preset
I tried the trial of LR and it drove me nuts, there's no reason why SPP can't get the greens right as the SD9 has no issues with that (only assumed the SD10 was OK from the reports here)

--
Please ignore the Typos, I'm the world's worst Typist

 
Lightroom is a charm to work with, nothing crashes/looks weird/gets
on your nerve.
Well, except that the whole GUI looks childish, some of the scroll
bars are on the wrong side, and the entire interface is inexplicably
modal, but we mustn't quibble, I suppose.
?CHildish? I think it looks totally OK and everything is at its place.
Lightroom's real merits all come from its underlying Camera Raw
technology. If you've got Photoshop, I say stick with Camera Raw and
don't hand Adobe extra money for the same technology gummed up in a
freak interface with a new name slapped on it.
Disagree. The real merit is the integration of a decent raw converter with an extensive parametrization, an archiving system and the output section (Print/Web/File). And the possibility to create presets for everything. Anyways, if the interface does not work for you it's not worth it of course. Maybe they should offer different skins and layouts.

O.
--
http://www.flickr.com/photos/ollivr/
http://www.flickriver.com/photos/ollivr/popular-interesting/
http://seen.by.spiegel.de/ollivr-1
 

Keyboard shortcuts

Back
Top