? about PS7 output from 2 different computers

C
Posted By
CygnusX1
May 25, 2004
Views
554
Replies
28
Status
Closed
I have a PowerMac G4 and a Powerbook G4.
Both connected to an Epson 1280, using a custom profile for a specific paper.

Both running exact versions of OSX(10.3.3) and all settings in PS7 exactly the same. I get great prints from the the PowerMac with the custom profile, however the exact same image from the PowerBook using the exact settings in the 1280 driver & PS7 prints a little less desireable.

The custom profile for the 1280 was built with an output target from the PowerMac so I assumed that printing on the same 1280 that both computers are connected to would yield exacting results.

Is this the right assumption or is a custom profile for the output from The PBG4 needed too even if all the settings and the paper used with it’s custom profile are identical?

Thanks
Related Tags
computer difference output

Must-have mockup pack for every graphic designer 🔥🔥🔥

Easy-to-use drag-n-drop Photoshop scene creator with more than 2800 items.

R
Ram
May 25, 2004
Your problem is not the output profile but the monitor profile on the Powerbook. Photoshop uses the data in the monitor profile for the conversion just prior to printing.

You need to recalibrate the monitor, starting with a fresh canned profile, not your current hosed profile and save the new profile.

Check out this link:

<http://www.gballard.net/nca.html>
C
CygnusX1
May 25, 2004
Thanks Ramon.

I had susupected that may be the case, yet wasn’t certain thinking the color settings and custom profile would be fine.

Thanks again.
R
Ram
May 25, 2004
You’re welcome, Cygnus. If the monitor attached to your G4 is a CRT, you’ll soon find that the Powerbook’s LCD won’t be as easy to calibrate.
C
CygnusX1
May 25, 2004
If the monitor attached to your G4 is a CRT, you’ll soon find that the Powerbook’s LCD won’t be as easy to calibrate.

The monitor on the PowerMac is the 20" cinema display. I did calibrate it (visually under controled lighting 5000k) and I was really surprised how very close the colors match the prints from the Epson 1280.

I use the Premium Semigloss with a custom profile from Andrew Rodney, and it really is spectacular considering the whole LCD/CRT debate. I imagine the difference in color/hues between the print and the LCD is truly no more than a 2% difference on some colors and some are just right on the money.

Apple’s LCD is the only one I’ve been able to accomplish this with, thus far.
P
progress
May 25, 2004
Ramon…im intrigued, why would the process use the monitor profile for conversion? surely its there just to display the file properley, not alter it?? ie the monitor is calibrated by the profile, not the file calibrated to the monitor…
R
Ram
May 25, 2004
Progress,

I believe Chris and/or Bruce explained this in great detail. G Ballard has a short version of the explanation on his site. Or you can search old forum messages.
R
Ram
May 25, 2004
In short, there are two parts to the Monitor Profile. Photoshop uses both.
R
Ram
May 25, 2004
Progress,

Sorry, I can’t find the reference to the relation between the conversion engine and the monitor profile when sending the image to the printer. Bruce or Chris will correct me, I’m sure.
C
CygnusX1
May 26, 2004
I’ve read this too that a bad monitor profile will cause issues on out put.

I wonder if PS takes the xyz values of the monitor profile into account when converting/editing an image.

I’ve calibrated and now have one profile with the 2.2 gamma and one with 1.8, I’ll determine which suits me best.
P
progress
May 26, 2004
cygnus, thats my point (not wanting to start an argument here, just i think its interesting…or nutts ;))…the display profile is just that, a display profile…im questioning the logic suggested because it would seem to indicate that 2 different monitors not using a canned profile but using a puck derived profile could print the same file out differently because the profiles would be different despite both the monitors being calibrated….seems weird huh…

no two monitors are the same remember despite them being able to be made to get close with individual custom profiles…but that changes their printing behaviour?

think bad monitor profiles can cause problems if you work to correct them…ie your profile displays whites with magenta, you try and kill the magenta, your print turns out bluey…thats how, but with no touching with sticky fingers i dont think it should make a difference.
C
CygnusX1
May 26, 2004
the display profile is just that, a display profile

This has been my thought for the most part.
I would have imagined that the RGB space in PS … say ColorMatch RGB would be all that matters and that would in turn have PS convert to the destination Profile in the "Print Preview".

I suppose I would like to hear from someone that PS7/CS actually takes the xyz values of the monitor pixels and uses that to calculate any out put conversions (odd but may be true)

I did use a very interesting test to take the RGB value readings using the Apple DigitalColor Meter (utilities folder) and the OEM LCD profile gave the most accurate reading of the Photoshop Red/Green/Blue swatches in the default swatches.

i.e. the color picker gave the red reading as R:255 G:0 B:0 etc. where as any calibrated profiles (custom) were not that absolute. R:253 G:X B:X
R
Ram
May 26, 2004
I noticed both Bruce Fraser and Chris Cox have posted elsewhere recently but have not addressed the issue in this particular thread.

As of now, I’m inclined to agree with Progress, but in the back of my mind I still have a memory of reading about how a monitor profile can indeed affect output, even without manipulating the image.

I hope either Bruce or Chris (or anyone else, of course) sets me straight.
GB
g_ballard
May 26, 2004
the cms converts source space to target space
I don’t monitor profile in there

are you saying otherwise?
R
Ram
May 26, 2004
At one point I was (or we were), don’t ask me why or how.
P
progress
May 26, 2004
ah, i think i see what could be clouding the issue…

colourmatchRGB is your colour space, its not your monitor profile…yes your colourspace settings need to be identical between RGB and CYMK or whatever if your to achieve identical conversion or output…your monitor profile is what your calibration method generates, and IMO just used to make the file look how it should on screen…as i see it, it fits inbetween your eyes looking at the monitor and the file in whatever colour space its in.
I think of it like the monitor cable, so to speak, and as far as i see it it should make about as much difference to your print output as your monitor cable 😉

so to cut the waffle

monitor space/profile = just used for calibrating the monitor, not used in conversion (as far as i know) (unless u been a bad lad and are working in your monitorRGB..a naughty no no;))

source space/profile or target space/profile used as a basis for conversions and a basis for your monitor profile to know what to do in order to display correct colours.
R
Ram
May 26, 2004
Progress,

You were making, well, progress in making sense of the whole thing, until you got to the cable analogy and, especially, the last paragraph in your post, with which I disagree (at least for now). Thanks for bringing it up.

Let me try to explain to myself what gives:

1.– Monitor profile:

(QUOTING BRUCE FRASER): >>>>>>>

The truth of the matter is actually simpler than it’s been made out to be in this thread, but it involves letting go of the cherished notion that profiles have a merely descriptive role. The notion is true for all profiles EXCEPT monitor profiles, and we have Apple to thank for making things convenient but confusing.

Unlike all other device profile types, monitor profiles have a calibration tag — the ‘vcgt’ tag (which stands for ‘video card gamma tag’ so it’s the video card gamma tag tag, just as the System folder used to be the System Folder folder…).

When you calibrate a monitor, you *may* adjust the individual guns to set color temperature, and you *do* set the gain and bias (aka contrast and brightness) controls to set the black and white luminance, but the gamma adjustment is always done by tweaking the lookup table in the video card that translates RGB counts to analog voltages. You can adjust the color temperature using the video LUT too, though it’s better to do it with the guns.

The vcgt tag contains that lookup table, and it gets loaded into the video card when you choose the monitor profile that contains it.

That’s why the screen changes, even with non-color-managed apps, when you choose different profiles. It’s not a question of apps using or not using the monitor profile — you’re simply plugging a different adjustment into the video card, so it affects everything that gets sent to the display.

The rest of the profile deals with correlating RGB counts with some specific color appearance, usually in XYZ (Lab is used for table-based profiles, XYZ for matrix-based profiles, which most display profiles are.) When that part of the profile is hosed, color-managed apps look bad.

The way monitor compensation works isn’t by converting the pixels in and out of XYZ (or LAB). Instead, the app looks at the doc profile and the display profile, and builds an RGB-to-RGB conversion that gets applied to all the data sent to the display.

END OF BRUCE FRASER QUOTE [Emphasis mine]

So the monitor profile is nowhere near as passive as the monitor cable.
R
Ram
May 26, 2004
Now, as for the last paragraph of your post (# 15)

source space/profile or target space/profile used as a basis for conversions and a basis for your monitor profile to know what to do in order to display correct colours.

Perhaps the reason I disagree with that is that I’m not sure whether you are equating source space/profile with target space/profile when you write “source space/profile or target space/profile” or suggesting that they‘re interchangeable.
R
Ram
May 26, 2004
For the sake of thoroughness, here’s the thread from which I extracted the above Bruce Fraser quote:

Bruce Fraser "Monitor profile" 6/9/03 6:19pm </cgi-bin/webx?13/31>
TL
Tim_Lookingbill
May 26, 2004
Test by building a wacked looking profile by adjusting the separate RGB sliders to some odd off colored cast and choose any gamma setting afterward. Does your prints show the same wacked cast you’ve set your monitor to in the profile?

Let us know, it didn’t on mine.
R
Ram
May 26, 2004
If you’re addressing me, Tim, forget it. I’m not masochistic in the least. 🙂
TL
Tim_Lookingbill
May 26, 2004
No, Ramon, I was addressing Cygnus on how much the monitor profile plays in a CM workflow.

It’s still hard to keep in my head how it all works, but that test always clarifies it for me, at least.
C
CygnusX1
May 27, 2004
Thanks Tim, I’ll play with that and post back.

I think that what threw me off (refer to original post) was how the exact same print on the eaxct same paper with the exact same Custom profiles(paper) and color settings in PS7 would yield different results just because it was from two different computers to the same printer, the 1280.

Thus my question about the monitor profile.
I will say this though, calibrating the 20" ACD is easier than the PB LCD, I also notice the printts more closely match the 20" display, and after all the Apple 20" & 23" are SWOP certified for what that’s worth ( a lot in my books).
R
Ram
May 27, 2004
Cygnus,

what threw me off (refer to original post) was how the exact same print on the exact same paper with the exact same Custom profiles(paper) and color settings in PS7 would yield different results just because it was from two different computers to the same printer, the 1280.

Yes, that is indeed very puzzling and that threw me off too.
C
CygnusX1
May 27, 2004
And just to add, the print driver settings were set exactly the same too. Ramon, I’m going to try a few things and as Tim mentioned too with creating a wacked profile just to see the difference.
P
progress
May 27, 2004
ramon,

all im saying with the target & source profiles is that they have the sameish effect as compared to the monitor profile which does something different…(im crap at explaining things)

to quote bruce "the app looks at the doc profile and the display profile, and builds an RGB-to-RGB conversion that gets applied to all the data sent to the display"…i think thats a bit open to interpretation, here’s how i see it…

the app needs to look at the doc profile to see how say "red" should look on the press (each press prints red different), then it looks at the monitor profile to see how the screen needs to make that "red", then it builds and inbetween conversion so that the "red" gets sent to the monitor so its displayed correctly…but the important thing is that its just sent to the display like bruce says…i interpret that as the end of its use. For all that i see it the monitor profile is a branch away from the workflow just for display purposes and has no effect on the workflow…yes its generated from the workflow, but thats logical because how else would it work.

of course i could be completely wrong…but thats where my logic takes me.

cygnus, are there any colour settings outside of PS that could get in the way, esp in printer drivers?
P
progress
May 27, 2004
have you tried making a PDF or postscipt file and printing that outside of PS?
R
Ram
May 27, 2004
Progress,

Thanks for clarifying.

For all that i see it the monitor profile is a branch away from the workflow just for display purposes and has no effect on the workflow…

Indirectly it does, of course, in the sense that an inaccurate monitor profile would/could lead you to perform inappropriate corrections or manipulations of the image.
P
progress
May 27, 2004
yep, thats for sure 😀

Must-have mockup pack for every graphic designer 🔥🔥🔥

Easy-to-use drag-n-drop Photoshop scene creator with more than 2800 items.

Related Discussion Topics

Nice and short text about related topics in discussion sections