[argyllcms] Re: ArgyllCMS: shadow details and blue color issues. What I'm doing incorrectly?

  • From: "Xavi" <aruiz@xxxxxxxxxxx>
  • To: <argyllcms@xxxxxxxxxxxxx>
  • Date: Fri, 26 Oct 2012 17:04:50 +0200

Thank you for your help Nikolay.
 
"The spatial dithering allows to print arbitrary RGB values, not only
INTEGER 0..255, for example, You had to round RGB values from xicclu -fb or
-fif to closest integer. With dithering enabled, the dithering algorithm
will mix-up the pixels of different but closest values to obtain desirable
intermediate value with higher tolerance. You can use 16-bit raster images,
but when printing they will be re-quantized down to 8 bit with dithering by
Photoshop or another SW. I'm enabling the dithering almost always if I use
8-bit images. I want not to loss intermediate device values."
 
Seems that's a way to improve the accuration of the profiles then I will
also enable it on my profiles when I discover why my profiles have a very
high deltae.
 
Thanks.
Best Regards,
Xavi.
 

  _____  

De: argyllcms-bounce@xxxxxxxxxxxxx [mailto:argyllcms-bounce@xxxxxxxxxxxxx]
En nombre de Nikolay Pokhilchenko
Enviado el: jueves, 25 de octubre de 2012 6:40
Para: argyllcms@xxxxxxxxxxxxx
Asunto: [argyllcms] Re: ArgyllCMS: shadow details and blue color issues.
What I'm doing incorrectly?


Thu, 25 Oct 2012 01:58:39 +0200 "Xavi" wrote:



I also have analized this case. I have compared the original tiff file
generated by printtarg versus the resized, with Ps, tiff file nad the values
of every patch is exactly the same.

OK. This is not a source the problem.



On another email you commented " I'm using ImageMagic "convert" utility to
crop and resize Argyll targets into desirable format."
What I see that your patches, after this converssion, haven't a regular
color. For exampl, if I analize the yellow color patch with Ps, the
information of each pixel varies. A pixel has a Lab 243,222,88 and the pixel
that limites has a value 242.221,87 [Lab]. This not occurs when resizing
with Ps. All the pixels, of a same color patch, have the same Lab value.

I've didn't use ImageMagic for preparing Test4.tif. This pixel difference is
due to enabled dithering in printtarg.





..I used a resized TIFF file, created without the -D ( Dither 8 bit TIFF
values down from 16 bit) 
Do you think that's important to use the -D option when create the TIFF
file?

The spatial dithering allows to print arbitrary RGB values, not only INTEGER
0..255, for example, You had to round RGB values from xicclu -fb or -fif to
closest integer. With dithering enabled, the dithering algorithm will mix-up
the pixels of different but closest values to obtain desirable intermediate
value with higher tolerance. You can use 16-bit raster images, but when
printing they will be re-quantized down to 8 bit with dithering by Photoshop
or another SW. I'm enabling the dithering almost always if I use 8-bit
images. I want not to loss intermediate device values.

Other related posts: