Epson Printer profile and posterization

[fred888]

Hi,
I've created a custom profile for my 3800 on Epson Traditional Paper (Enhanced Mat).
I'm using Spyder3print.
The created profile looks very good for a lot of tones, skins are great, reds are much more graduted that with the canned profile.
The problem is in the blue. I've got a photo with highly saturated blue smoke, and I get some ugly color shift and posterization in the blue on this photo. The posterization is visible on the print and on the CS3 soft proof as well. with all the rendering intends.
In another way the canned profile does not show any posterisation. The saturated reds show a little banding but that's it.

As this is visible on the soft proof and the print is accurate to the soft proof I suppose this only comes from the profile.

I'm working in 16bits Adobe RGB. The only turnaround I've found is converting the image to sRGB. The conversion to sRGB change slightly the blues and after that the soft proof with the custom profile doesn't show any more posterization.  

The I've made several custom profiles with different mesures and target size and they have all the same behaviour.

Can someone explain to me where this may come from and how I can make it work correctly with this custom profile ?
Thanks for your help.
Fred

[BobbyT]

I too had the same problems with blue and purple posterization.  It turns out in my case when I printed the targets for Spyder3 Print I used the wrong media type in the printer driver.  When I reprinted the targets with the proper media type and made a new profile it turned out perfect.  Hope this helps.

[fred888]

Thanks for the tip.
I've choose the Epson Premium Luster as media type, I've base that choice on PixelGenius and other's recomandation for profiling this paper.

Considering that the PG profile seems to be excellent for the US version of this paper but does not fit very well the EU version (strong yellow color cast), and that the ETPP canned profile on the EU Epson site is created using Epson Glossy as media type,  I'm strongly wondering now if it may be useful to try to recretate the profile using the Glossy setting.... Could it be much difference between these 2 media ?

[Doombrain]

How many patches are you using to make the target, can you make a custom with 1600+?

I would also follow epson's recommendation to use PGPP, even thought the ink limit is the same for PLPP.

[fred888]

I've been doing 225 patches profile and an other  729 patches profile to get a better quality one.
Both are giving me the same posterization in the deep saturated blues when printing from a Adobe RGB or higher gamut file.
I don't have what to do a 1600+ patches except buying one.

If I get no other solutions I will probably take the time (and ink and paper !)  to recreate one using the PGPP to see if it changes something.

[Doombrain]

TBH you really need to be using more patches to remove as much guess work as possible when the ICC is created.

[eronald]

TBH you really need to be using more patches to remove as much guess work as possible when the ICC is created.
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The deep saturated blues are always a problem with few patches, I think the hue skews with the amount of ink applied.

Edmund