From: "jimhayes361" <jimhayes@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Saturday, July 13, 2002 2:47 PM
Subject: [Digital BW] Re: My workaround for the PS6 -> PS7 posterization
problem...
> --- In DigitalBlackandWhiteThePrint@y..., "Martin Wesley"
> <mwesley250@e...> wrote:
> > ----- Original Message -----
> > From: "jimhayes361" <jimhayes@j...>
> > To: <DigitalBlackandWhiteThePrint@y...>
> > Sent: Saturday, July 13, 2002 8:12 AM
> > Subject: [Digital BW] Re: My workaround for the PS6 -> PS7
> posterization
> > problem...
> >
> >
(snip)
> >
> > Then what would happen to all the people who do not have this
> problem? This
> > is something that is showing up in 1 or 2 systems so far, redoing
> the curves
> > would only be justified if the problem were universal.
>
> Well, true. We haven't asked everyone to do the test where you do the
> gamma 2.2 to sRGB conversion in each version and write down the
> hitogram mean, SD and median and see if they differ a little. It did
> for all of us involved in the discussion so something is probably
> happening-
>
> OTOH, you would then be right to question whether the amount of
> difference affects the actual print. So far only I and apparently
> coveylaw see a real difference on the print.
>
> But let's say that a good samaritan has lots of time and patience and
> prints out a step wedge in PS7 AND, and this is important, uses the
> space Adobe98 this time instead of sRGB for his (her) curve
> generation. Now the corrected curves will give the same values as the
> old sRGB curves did in EITHER PS6 or PS7. Therefore it is a useful
> thing to do since 1) the better color space is now used instead, 2)
> the tones are corrected for using the new color space so it matches
> tones when the old sRGB conversion was used, 3) it is indeed more
> universal...everyone can use it, whether in PS6 or PS7 with less error
> in conversion. Whether they had a problem or not originally, it would
> work for everybody, since it now uses Adobe98 space- which gives
> almost identical results in PS6 or PS7 (barring that strange
> microbanding I had and a bit more posterization which so far I haven't
> gone further to investigate).
Jim,
I feel a bit dim at times. The conversion between the PS6 and PS7 are easy
to compare. Just take the same 2.2 grayscale wedge file and convert it to
sRGB in each and then measure the results with the eye-dropper tool.
The sRGB conversion matches exactly in both versions of PS except at one
point, 95%. At this point the PS6 conversion gives 10,10,10 and the PS7
version gives 5,5,5. I did the same converting to Adobe RGB in PS and PS7
and they match at all points. I have posted a pdf file showing the
comparisons in folder:
Files > Message Related Files > 07_2002 uploads
I will be interested to see if you get the same values if you repeat the
exercise. In theory these should be system and OS independent.
>
> Should Paul be asked to do the pushups? Only if he wants to. He's done
> alot already for us. And it does depend on how many others are
> affected by the discrepancy how important it is to switch to Adobe98
> officially for all the curves.
I don't think that we should count on him. He has done more than his share
by far and doesn't even own a 1280. It is time for all the curve slackers
(which includes myself) to take the plunge and start doing their own RGB
separation curves and sharing them just as Paul has done. I will be happy to
host any and all curves in the Files section.
>
> > >
> > > He might be able to do it with a transfer curve, I don't know. He
> > > hasn't responded to any posts on or off list from me on this
> topic,
> > > unless I missed it.
> > >
> > > Also, there is still the unresolved issue of whether I get
> > > microbanding even using Adobe98 with PS7. I can't test it right
> now
> > > any further, as I'm short on ink to squander. My test print also
> still
> > > shows just a tiny bit more posterization in PS7 vs PS6 when using
> > > Adobe98. And of course the tones are different using this space.
> It's
> > > really crying out for a curve tweak.
> >
> > I am printing just fine from PS7 on my 1280. No microbanding and the
> quality
> > is unchanged from PS6. Any tweak would then give me and everyone
> else
> > trouble.
>
> Not if the tweak gave you identical tonal results- just using Adobe98
> instead of sRGB. All I'm saying is keep the output the same, just
> strengthen the reliability of the output by changing the workflow such
> that the conversion is to Adobe98 instead of sRGB. Paul shoots for the
> same step wedge- just with the Adobe98 conversion. In fact, on the MIS
> site he has already done this for the 1270 and a couple of others- and
> the 1280 if used with a MAc, if memory serves.
True, if the tweak is to convert everything over to AdobeRGB then I would
see this as a step in the right direction. The trend now is to apply the
curves in Adobe RGB space and to print with the Epson driver's color
management turned off. This makes the curves much less printer and OS
specific. The Dan Culbertson RGB soft proof method. A lot of work to go back
and redo all of the curves done in sRGB and with the original workflow but
probably worth it.
>
> At least one other person is having trouble, that's why I responded to
> this post. If you are using sRGB as your conversion space and you try
> a relatively dark print and you have a PC- well then I guess you DON'T
> have a problem, what can I say.
I am not seeing it in at the print level. Not a difference in the versions
of PS or between sRGB and Adobe RGB with the same file. I do realize that if
I tried the same thing with a different print I might get a different
result.
>
> If then you are happy with things as they are, then sure, keep on
> trukin'. Having mutiple curves, PS versions, and spaces for Paul's
> workflow might get a bit confusing for me though, ie, "try this in PS7
> and if it posterizes try PS6, or, maybe just convert to Adobe98
> instead of sRGB, unless you get banding..." I'm just after
> standardizing the curves as much as possible, probably to Adobe98, but
> maybe this just isn't possible.
I certainly agree on standardizing and having to shift back and forth
between PS6 and PS7 does not seem like a reasonable solution. The more
curves the better though. I have found that a change of curves or blending
two curves will often get me out of a posterization jam.
>
>
> Why not tweak the curves yourself for your own use?
>
> This is a really good idea, and probably the best advice to give
> anyone using MIS VM with all the variables of paper. I think we can
> fairly say that now just two people are starting to see a new
> variable...using PS6 vs PS7.
>
> But using one's own tweak, the correct values can be arrived at. The
> only problem is it may take quite a bit of trial and error to get the
> tonal changes even. Right now it's easier to just go back and use PS6.
Along those lines when I look at how close the conversion results of Adobe
RGB and sRGB are and how close the PS6 and PS7 conversions are (at least on
my system) my instinct is that you would have a tough time tweaking in such
small differences.
>
> > >
> > > Then the other solution is to just use PS6 until the 2200 comes
> out
> > > and go for it. That is a big unknown as well.
>
> >
> > BTW, I have seen some B&W 7600 output which uses the same inks as
> the 2200.
> > The results are similar to the 2000P. Odd tonal splits and a print
> that is
> > fairly neutral in tungsten lighting is yellow/green in daylight. I
> don't
> > know if these were good or poor examples of what the machine can do.
> I want
> > to see some more but if what I saw is "good" then I doubt you would
> be happy
> > with the hue or metamerism.
>
>
> That is discouraging, you would think that Epson would know they have
> to give everyone else a run for the money...all those $$$ carts should
> print out something worth printing, oh well...thanks for the advance
> opinion Martin. I ordered up a sample print from Blair (tssphoto) and
> I'll have a look for myself too.
Well it is a single sample and if you see something different, please let me
know. B&W aside I am interested in one to replace our 1270 for color
printing.
>
> > >
> > > You could buy an older computer and network it up on the OS of
> your
> > > choice with PS6 and dedicate the printer to it. A bit of bother
> there.
> >
> > Since I can't duplicate your problem using very similar equipment (I
> think
> > the only difference is that you are running Win98SE and I am on Win
> 2000), I
> > would urge you to continue to look for something in your set-up that
> is not
> > quite right.
>
> Yes, I will do that after two weeks or so. Thank you for all your
> generous help in trying to isolate the problem last week or so. I can
> use PS6 for now on my main machine. I don't need to add another
> computer myself. Again, you see, I was only responding to "Coveylaw"
> with possible options- he has MAC OSX I think.
Got it. I seem to recall you are off on vacation and I assume with camera at
hand so good shooting.
Martin