[argyllcms] Re: profiling camera
- From: Nikolay Pokhilchenko <nikolay_po@xxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Mon, 08 Aug 2011 18:18:51 +0400
08.08.2011, 16:13 nino loss wrote:
I did the test suggested by Iliah Borg, but couldn't notice any significant
difference between the two shots except a slight overall difference in
brightness (aprox. 0.04 stop). I than placed a mirror in the spot of the target
and couldn't see anything except some spots of dust.You have very good
conditions to target shooting in Your studio.
So I replaced the mirror with an old glossy 5x7 it8 in the same setup. The
resulting profile came out nice with a very low peak and average value. The
glossy old it8 performed better than the still quite new CC24?!
The lower dE is not means the better profile. The IT8 target just simpler by
spectral coefficients of reflection, than the CC24. Traditionally printed IT8
have the same colorants for all patches when the CC24 have custom colorants for
every patch group. So, when You've placed IT8, You get less metametrism because
of simpler spectrums of path reflections. The profile built with this IT8 will
be very precise and ideal when You'll shooting under the same light the glossy
color photopaper - the paper of same type and process as target was. But when
You'll shot real object like a peoples, fruits or plants, this profile can be
not optimal. Color Checker have more realistic spectral coefficients of
reflection and the image with profile built on this target can be (but not
obliged to be) more natural. The main issue of Color Checker can be a lack of
patches. So the result with 24-patches Color Checker can be worse than with
different target.
Also there are no shiny objects, because I work in a large black studio,
following a procedure similar to the one discribed here:
http://www.luminous-landscape.com/reviews/accessories/coloreyes-commercial.shtml
One light only to avoid mixtures. The strobe is at an angle that does not
reflect back into the camera. The light source is at a great distance from the
target so that illumination is very even, and using a black cutter in addition
to reduce on the closer side. Further screens in front and around the camera,
and all metal pieces covered, to reduce reflections.
Your studio is impressive. Can You describe a little the light source? Which
kind of lamp in it?
nino
On 8/8/2011 10:53 AM, Nikolay Pokhilchenko wrote:
May be You'll see the glare from light sources or bright objects around the
target. Even if the target isn't glossy, the glare influence is present anyway.
Try to follow by Iliah Borg's advice: shoot the target in right and up side
down positions and compare the profiles. If the results will be the same, the
problem is metametrism only.
07.08.2011, 16:15 nino loss wrote:
I want to try, but why should that be different? I didn't use a glossy
target this time.
On 8/5/2011 9:58 PM, Nikolay Pokhilchenko wrote:
>
> What if You shot the clean glossy paper sheet in place of target?
>
>
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