[argyllcms] Re: Best way to proceed?


On Saturday 31 May 2008 15:53:29 Ben Goren wrote:
> So, I've made some progress in this project, but I'm hoping that I'm
> not -- as I think I am -- doomed to doing everything the old-fashioned
> way.
>
> Attached is a small sRGB JPEG of one of the works. The art is pretty
> close; I think only those with a critical eye would be able to tell
> the difference, and the conversion to an email-friendly attachment has
> probably altered it about as much as it's off from the original. The
> print is a bit dark...I need to crank down the backlight on the display.
>
> I did all the color correction by fiddling with the sliders in Adobe
> Camera Raw. And, as a quick glance at the ColorChecker will show you,
> I did a *lot* of fiddling.
>
> I then shot a couple other pieces with the same lighting and ACR
> settings. They're also in the ballpark, but still in need of tweaking.
>
> Is there any hope of doing this colorimetrically?
>
> To make matters worse, some of the woods are very slightly iridescent,
> and change luminance (mostly) and hue (slightly) rather noticeably
> with shifting lighting angles....

I don't think this is iridescence but rather it is the characteristics of the 
wood grain which is a 3D structrure.  This causes it to absorb different 
amounts of light as the angle of the lighting changes as well as affecting the 
hue since the light is being reflected off of different parts of the wood 
structure.  This will be more pronounced in some types of wood and also in 
samples with more pronounced figure which will exibit this in a more 
pronounced way.  For example, a very nice violin will generally have highly 
figured (curly or flamed) maple in the back, sides and neck of the instrument.  
This will look like waves in the wood of the instruments back because the wood 
grain actually has waves in it.  If you hold one of these viewing the back 
while moving it so that the angle of the light changes you will see these 
waves move up and down the back of the violin.  This will look almost like the 
flames of a fire and this is where the term flamed maple comes from.


>
> Cheers,
>
> b&

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