Re: U.S. Web Coated (SWOP) v2 always produces blues that
Re: U.S. Web Coated (SWOP) v2 always produces blues that
- Subject: Re: U.S. Web Coated (SWOP) v2 always produces blues that
- From: "email@hidden" <email@hidden>
- Date: Tue, 3 Jul 2007 15:20:18 -0500
In Colorsync-users Digest, Vol 4, Issue 240, Msg. 4
Rich Apollo writes:
Try starting out in a different RGB colorspace.
AdobeRGB98
LabBlu = 30.2 69.2 -113.6
C M Y K
0.91 0.70 0.00 0.00 USSheetfedCoated
0.92 0.79 0.00 0.00 USWebCoatedSWOP
L* a* b* Hue Chroma
35.0 8.42 -40.9 4.92 41.3 USSheetfedCoated
39.5 9.26 -44.9 4.92 45.9 USWebCoatedSWOP
Results similar to sRGB: i) Cyan > Magenta and ii) Hue angles of
mapped
colors identical.
Harold
Okay we're talking about RGB, but... (and where are you setting Lab
values in decimal?)
not quite what I was talking about
If you set a color of 0R, 0G, 255B in Photoshop and try the
transforms. Also, sRGB and AdobeRGB are pretty similar in the blues.
I tried a bunch of these. Let's use ECI-RGB
So, 255 Blue in ECI-RGB
C M Y K
89 64 0 0 USSheetfed Coatedv2 (relative)
92 65 0 0 USSheetfed Coatedv2 (perceptual)
88 72 0 0 USWebCoated SWOPv2 (relative)
91 74 0 0 USWebCoated SWOPv2 (perceptual)
255 Blue in AdobeRGB
C M Y K
88 70 0 0 USSheetfed Coatedv2 (relative)
90 72 0 0 USSheetfed Coatedv2 (perceptual)
86 77 0 0 USWebCoated SWOPv2 (relative)
88 79 0 0 USWebCoated SWOPv2 (perceptual)
255 Blue
L a b
31 70 -111 AdobeRGB
35 50 -105 ECI-RGB
30 69 -110 sRGB IEC61966-2.1
Then, back to your original example, Harold
Blue = 30 69 -114 (as close as I could do in Pshop)
C M Y K
88 70 0 0 sRGB -> USSheetfed Coatedv2 (relative)
91 72 0 0 sRGB -> USSheetfed Coatedv2 (perceptual)
89 64 0 0 ECI-RGB -> USSheetfed Coatedv2 (relative)
92 65 0 0 ECI-RGB -> USSheetfed Coatedv2 (perceptual)
86 77 0 0 sRGB -> USWebCoated SWOPv2 (relative)
89 80 0 0 sRGB -> USWebCoated SWOPv2 (perceptual)
88 72 0 0 ECI-RGB -> USWebCoated SWOPv2 (relative)
91 74 0 0 ECI-RGB -> USWebCoated SWOPv2 (perceptual)
Take a look at the primaries and secondaries in ColorThink, also.
Rich Apollo
G7 Certified Expert
Adobe Certified Expert, Photoshop
314-344-1144
email@hidden
www.prioritylitho.com
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