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Author Topic: Independent Study Course  (Read 4163 times)
adamlogan
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« on: March 28, 2010, 02:28:42 AM »
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Hi folks. I'm doing a independent study course this quarter for myself. I wanted to give Argyll a shot and see if it is a good alternative to using the software that comes with the i1 pro e.g. i1Match & ProfileMaker. I am thinking about buying an i1 pro basic and using Argyll since theoretically the basic and pro model is exactly the same with the exception of unlocked features in software for the pro model. Not only that, but I believe the capabilities of Argyll goes far beyond the capability of the proprietary software. But, I am relatively new to command line applications.

Fortunately I have been using the bash shell with the Terminal application on the Mac for a couple months now and am falling more and more in love everyday. I am also learning to use the shell via ssh to a Sun server, and using the shell within virtual machines such as Ubuntu as a guest machine on my Mac host, and I have Arch Linux on my laptop as well.

Anyways.. At this point I have figured out how to download, untar and change the path variable in the default bash shell environment on my mac. Originally I had the Argyll folder in /usr/bin/local/ but I decided to move it to ~/Applications since I want to be able to open the html documents in the Docs folder and there are no other users on this computer. I also recursively chowned the Argyll directory and all content with 555 permissions to be safe. Perhaps it's a bit over protective but it's good exercise for me anyways and an opportunity for me to learn the ins and outs of traditional unix permissions.

I have read several of the documents several times and have come to a very very basic understanding of the preferred multi-step manner of calibrating the display, creating and installing profiles. However, I know that I am inexperienced and am hoping for tips that more experienced people can give.

Right now I am focusing on optimal settings for monitors. Also I'm confused about all the brightness, gamma, options and what would be appropriate in terms of the physical monitor settings (OSD),OS brightness slider, and for settings/flags for dispcal. Using i1Match as a starting point, it recommends using a native white point, Gamma of 2.2, and 120 Luminance for lcd displays. Then there is the whole thing about the "ideal curve"  In the image attachments below I have reset the factory defaults. Am wondering if I should change anything? I am especially tempted to change the RGB values to 70,70,70 or maybe even 80,80,80. I imagine that would change the brightness though. What do you guys have to say about that? Also on the main osd menu it says that 60hz is "optimum" and currently it is at the highest setting I could see in the display settings of OSX which is 75hz.

I read that in some cases it is better not to change things on the osd settings. Compounding this question is the brightness slider in the OS.. Where should that slider be set? Anyways, I'm sure my awkwardness is apparent and I am asking for advice on how to proceed. Not only do I want to know how to go about calibrating my lousy/old dell display but it would be good to know how to go about this with the Apple displays that are available in the computer labs at school too since ultimately I will probably need to demonstrate what I have learned on a lab computer so that my teacher might possibly teach his students in the future.

Please note that this post is not complete, but is a starting point. I intend to keep my project confined to this single thread for simplicity. Will come back tomorrow and edit/add more. Constructive feedback would be appreciated.

[attachment=21109:osdmenu.jpg]
[attachment=21110:imagesettings.jpg]
[attachment=21111:colorsettings.jpg]
[attachment=21112:brightnesscontrast.jpg]
« Last Edit: March 29, 2010, 02:50:20 AM by adamlogan » Logged
Czornyj
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« Reply #1 on: March 28, 2010, 05:22:14 AM »
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I'd suggest to use a GUI for Argyll:
http://colorhacks.blogspot.com/

As for your further questions - there's an excellent "Fogra Softproof Handbook", that thoroughly describes the basics of monitor calibration:
http://forschung.fogra.org/dokumente/uploa...of_Handbook.pdf
« Last Edit: March 28, 2010, 05:22:35 AM by Czornyj » Logged

adamlogan
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« Reply #2 on: March 28, 2010, 04:49:22 PM »
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@ Czornyj

Thanks. Am reading the pdf now. Have already tried dispcalgui on the computer labs at school. It fails, I think it might have something to do with the fact that student accounts do not have admin privileges or perhaps due to colorsync. The profiles at /Library/ColorSync/Profiles are read and execute only which is the only location of the display's factory default profile which dispwin cannot change or uninstall I suspect. Can't be sure though. I don't remember the exact error, I'll reproduce it and post when I get a chance. Have not tried using dispcalgui on my personal computer though.

I like the javascript gui. It seems like a quick way to get familiar with common commands and flags.
« Last Edit: March 28, 2010, 05:21:01 PM by adamlogan » Logged
MPatek
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« Reply #3 on: March 28, 2010, 11:49:47 PM »
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I have spent some time with Argyll CMS and monitor calibration - on Windows. Check out my web section if you find it useful for your study (Argyll CMS). There is also pag dedicated to monitor calibration (Monitor calibration).


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Marcel

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adamlogan
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« Reply #4 on: March 29, 2010, 03:05:09 AM »
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@ MPatek

Thank you very much. Your website will be of much use to me. Have looked over everything in the last few hours and a few things are clearer to me. Have not had time to do try out the commands or whatnot but that is fine will have plenty of time to do so this week.

One thing that puzzles me, why did you use the sRGB gamma curve? Does that limit the gamut of the monitor at all? Intuition tells me to use the l* for some reason.. The only reason I can explain your choice is your monitor must be like mine with only 100 values per RGB channel and is 8bit rather than 10.

Something occurred to me, I am not sure if it is true but from what I understand I have two things capable of changing LUT, ColorSync and the Argyll utilities. Argyll loads and unloads LUT values for the sake of pre calibration/calibration etc but is not responsible for resetting/clearing or changing the installed profile for a device permanently which is ColorSync's responsibility. Did I get that right? I am guessing the failures I mentioned earlier was just me being clueless.

One issue I am experiencing right now is being unable to use i1Match. I get as far as calibrating the i1pro with the white reference tile and it fails everytime. Tried logging out logging back in, restarting no difference. I thought maybe it was just Argyll connecting with the device before i1Match does (I remember before how sensitive i1Match or ProfileMaker was about other programs accessing the device) but I am not so sure now.
« Last Edit: March 29, 2010, 03:10:08 AM by adamlogan » Logged
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« Reply #5 on: March 29, 2010, 10:44:03 AM »
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Quote
Intuition tells me to use the l* for some reason.. The only reason I can explain your choice is your monitor must be like mine with only 100 values per RGB channel and is 8bit rather than 10.

All video cards are 8 bits per channel at the moment with the exception of some cards for use in the medical and scientific industries. Some monitors such as the higher end NECs have higher resolution monitor LUTs but their inputs are still 8 bits. They use software which can directly interface with the monitor itself and change the settings in the monitor LUT at a higher resolution. The advantage of this is that the video card can send out a 1:1 mapping so no change is made to the 8 bit video LUT (which means you aren't compromising any resolution). NEC's Spectraview software can do this. Integrated Colors' "Color Eyes Display Pro" can do this (it works best with Eizo monitors... the DDC/CI comm protocol is not much of a "standard" as one would hope to see and some companies like NEC aren't very forthcoming in sharing their version of the standard so it isn't compatible with all monitors that support DDC), LaCie has their "Blue Eye" software. There's a few other packages as well.

 sRGB vs. L* might stir a religious war but the whole point of monitor calibration and profiling is to match print output so I say get a good reference print, view it under full spectrum lighting (Solux) and see what matches screen to print best (make sure you're using the correct soft proofing profile from the lab that printed your print).

Quote
Something occurred to me, I am not sure if it is true but from what I understand I have two things capable of changing LUT, ColorSync and the Argyll utilities. Argyll loads and unloads LUT values for the sake of pre calibration/calibration etc but is not responsible for resetting/clearing or changing the installed profile for a device permanently which is ColorSync's responsibility. Did I get that right? I am guessing the failures I mentioned earlier was just me being clueless.

Which LUT? The monitor LUT or the video LUT?

Quote
One issue I am experiencing right now is being unable to use i1Match. I get as far as calibrating the i1pro with the white reference tile and it fails everytime. Tried logging out logging back in, restarting no difference. I thought maybe it was just Argyll connecting with the device before i1Match does (I remember before how sensitive i1Match or ProfileMaker was about other programs accessing the device) but I am not so sure now.

Make sure you've quite any application that uses the Eye One Pro. If you have Eye One Match launched and you attempt to use any other package be it Color Eyes, Spectraview, or Argyll it will most likely fail because whatever has been launched first will grab the puck and won't release it until you quit the app.

Cheers, Joe
« Last Edit: March 29, 2010, 10:44:43 AM by shewhorn » Logged
adamlogan
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« Reply #6 on: March 29, 2010, 07:38:07 PM »
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@ shewhorn

Thanks for the feedback. I was referring to the graphics card when I mentioned LUT. I know the deal about applications not letting go of the puck. That is why I attempted logging out, and rebooting. Checked the Login Items as well to make sure no applications were starting up and taking control of the puck. It's not that i1Match does not see the puck, it's that calibration of the white reference tile fails.. =/ hope it's nothing serious. Didn't see anything related to Argyll or i1Match in PS or Top either.
« Last Edit: April 01, 2010, 10:47:22 AM by adamlogan » Logged
MPatek
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« Reply #7 on: March 30, 2010, 10:04:20 PM »
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@adamlogan

Quote
One thing that puzzles me, why did you use the sRGB gamma curve? Does that limit the gamut of the monitor at all? Intuition tells me to use the l* for some reason.. The only reason I can explain your choice is your monitor must be like mine with only 100 values per RGB channel and is 8bit rather than 10.

As shewhorn pointed out, the choice of sRGB/L* curves is nearly arbitrary. I used the -gs flag in Argyll to profile for gamma 2.2 as implemented in standard sRGB encoding (short linear part in shadows). It will not limit gamut of your monitor (primaries are set as measured off the monitor). It is only the tonal curve that is affected. You can choose L* if you see it fit better.

Quote
Something occurred to me, I am not sure if it is true but from what I understand I have two things capable of changing LUT, ColorSync and the Argyll utilities. Argyll loads and unloads LUT values for the sake of pre calibration/calibration etc but is not responsible for resetting/clearing or changing the installed profile for a device permanently which is ColorSync's responsibility. Did I get that right? I am guessing the failures I mentioned earlier was just me being clueless.

I am not working with Mac system, but I think of ColorSync as CMS under Windows. It ensures that profiles are applied to displays under color managed applications (Photoshop). It simply handles icc profiles - it does not changes them. If no defult profile exists, Windows will choose sRGB. Argyll can only clear the video card LUT (not internal monitor LUTs). Your understanding of Argyll/Colorsync function is essentially correct.

good luck,
Marcel
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Marcel

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adamlogan
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« Reply #8 on: March 31, 2010, 05:15:20 PM »
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Ok so here's an interesting one. How do I reset an external apple display to factory default settings? I found this old thread which suggests resetting PRAM & NVRAM but I am on a lab computer; no admin privileges. Will have to try it at home and see if it works on my personal computer. I was able to reset PRAM, but was not successful with NVRAM as I cannot get to the open firmware screen. I guess it does not matter much anyways, afaik there are no rgb gain controls. Only thing is the brightness control on the monitor itself and brightness slider in the os. So it seems like the display does not really allow users to change the native LUT of the monitor using traditional methods. Seems like one could only do it artificially with software. Correct me if I'm wrong. ColorSync Utility allows you to reset factory profile, I guess that's pretty much the same thing to resetting a display to factory defaults with the exception of brightness.
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adamlogan
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« Reply #9 on: March 31, 2010, 06:11:32 PM »
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accidentally double posted somehow
« Last Edit: April 01, 2010, 10:49:52 AM by adamlogan » Logged
adamlogan
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« Reply #10 on: April 07, 2010, 07:19:08 PM »
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Ok so I've been working on this. I followed MPatek's guide very loosely. This is the general workflow I have developed so far.

//Report on uncalibrated monitor
dispcal -v -d1 -c1 -yl -H -K -R -P 0,1,3

//calibration of Apple display
dispcal -v -d1 -c1 -yl -N -H -qh -b 120 -g 2.2 -P 0,1,3 basename

//create test patches for creation of profile
targen -v -d3 -g33 -f1000 basename

//measure targets
dispread -v -d1 -c1 -yl -N -H -P 0,1,3 inputfile outputfile

//create profile
colprof -v -D "description eg seen in photoshop/colorsync" -qh -bh -S inputfile outputfile

//installs profile
I just place the resulting .icc profile in ~/Library/ColorSync/Profiles/ and load the profile in the ColorSync application.


Right now I'm focusing on the parameters for colprof. With the -S flag, I'm not quite sure what to do. Photoshop provides soft proofing on the fly doesn't it?

Gamut mapping is something I encountered only last quarter when I saw Eric Chan's tutorial about hidden alternative gamut mapping options in i1Match. The -S flag, does it function by including gamut mappings into it's tables or what?

EDIT:

I googled "popular gamut mapping choices" and top hit was a page on the argyll site heh. Guess I asked too soon =/. So from what I understand the device space to PCS is locked down and cannot be changed IE I can't invent a new intent? and the PCS to device eg printer is limited to 3 of my gamut mappings of my choosing eg Logo Classic, Logo Colorful, Logo Chromaplus as examples?

So from what I understand a shaper/matrix profile would be sufficient for a display profile, but for a printer profile I guess cLUT would be the way to go? This is kinda muddy in my mind.
« Last Edit: April 08, 2010, 01:16:34 PM by adamlogan » Logged
jerryrock
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« Reply #11 on: April 08, 2010, 10:10:09 AM »
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Quote from: adamlogan
Ok so here's an interesting one. How do I reset an external apple display to factory default settings? I found this old thread which suggests resetting PRAM & NVRAM but I am on a lab computer; no admin privileges. Will have to try it at home and see if it works on my personal computer. I was able to reset PRAM, but was not successful with NVRAM as I cannot get to the open firmware screen. I guess it does not matter much anyways, afaik there are no rgb gain controls. Only thing is the brightness control on the monitor itself and brightness slider in the os. So it seems like the display does not really allow users to change the native LUT of the monitor using traditional methods. Seems like one could only do it artificially with software. Correct me if I'm wrong. ColorSync Utility allows you to reset factory profile, I guess that's pretty much the same thing to resetting a display to factory defaults with the exception of brightness.

Apple monitors do not have an adjustable LUT. The only physical control is the brightness/backlight setting. Your monitor calibration/profiling software is adjusting the output of your video card.
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« Reply #12 on: April 09, 2010, 01:44:12 PM »
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Quote from: adamlogan
I googled "popular gamut mapping choices" and top hit was a page on the argyll site heh. Guess I asked too soon =/. So from what I understand the device space to PCS is locked down and cannot be changed IE I can't invent a new intent? and the PCS to device eg printer is limited to 3 of my gamut mappings of my choosing eg Logo Classic, Logo Colorful, Logo Chromaplus as examples?

So from what I understand a shaper/matrix profile would be sufficient for a display profile, but for a printer profile I guess cLUT would be the way to go? This is kinda muddy in my mind.

Adding the -S flag in colprof assists in creating of B2A lookup table, that is a table for translating PCS (usually LAB D50) to device values. Reason for using existing printer profile is to allow for accurate gamut mapping between PCS-monitor when priter profile is used. Printer profile is used to only build the B2A table to become part of the display profile. It won't get embedded in it.  -S flag builds two intents: perceptual and saturation.  Read more on Argyll's page.

Gamut mapping intents are quite open to modifications - however, based on ICC definition, there are only three tables in each direction. A1/B1 or B1/A1 for colorimetric (relative or absolute), other (0,2) for perceptual and saturation intents, respectively. These are open to modifications (to some extend) and each manufacturer (software provider) has their own algorithms. True, they have to follow general principles of gamut mapping, but usually their tables will strive for "nicer" colors/contrast. For many devices (except of printers), most of A2B tables are colorimetric regardless of the intent you choose.

Shaper/matrix profiles are simple and smaller in size. However, they may not work well for devices that are not RGB additive, i.e. do not follow colorimetry well. Higher-end monitors (e.g., Eizo) are fine with shaper/matrix profiles. You have to see how your monitor behaves. If colors are off, LUT-based profiles might solve the problem.

good luck,
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adamlogan
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« Reply #13 on: April 17, 2010, 01:09:28 AM »
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I feel like I'm flying blind, so I'm checking out vrml representations of the gamuts of my devices/profiles. So far I have compared the dell factory default manufacturer profile for the monitor I use at home and the current profile I have made for it. Am using freewrl to view it. I just used iccgamut command with no options of both .icc profiles, then used viewgam with no options specified as well and just indicated the two infiles and outfile. Is it possible to specify options per profile with the viewgam command? IE 1st profile is red, 2nd is blue, third is green. viewgam -? showed "usage: viewgam { [-c color] [-t trans] [-w|s] infile.gam } ... outfile.wrl" and so I got the impression that I could specify options per profile but got errors until I removed all the brackets, ended up looking at a spinning cube in freewrl. I take it I have to specify exactly what I want each device/profile to look like in the iccgamut command? Seems like a cumbersome way to view and compare profiles.

I realize I should probably measure the characterization of my display with the factory profile installed rather than use the factory profile itself to compare before/after results. Will have to get around to that tomorrow.

I remember my color management teacher using a photoshop plugin called colorthink. I recall specifically that there was a "visible spectrum" gamut. I believe that is the CIE colorspace? Am wondering where I could get that and add it to my visualization. Would it happen to be included with the Adobe profiles?
« Last Edit: April 17, 2010, 01:19:12 AM by adamlogan » Logged
MPatek
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« Reply #14 on: April 17, 2010, 04:33:52 PM »
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To visualize gamut of icc profiles, ColorThink is indeed a great product. There is a demo version on  CHROMIX web site. It is a standalone program not Photoshop plugin.
Another capable product is Gamutvision.
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adamlogan
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« Reply #15 on: April 20, 2010, 12:19:36 PM »
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What do you guys suggest as far as cleaning an it8 scanner test target? I gently used an air hose to blow off dust. Should I avoid using glass cleaner/screen guardian type of products to clean the target or is it ok to use a specific product? Did a search on google and on this site and didn't see any obvious answer.

While we are at it, I guess it would not hurt to ask the same about cleaning the scanner bed.

Teachers in my program have given me a commision to scan some large artwork. I'm going to have to either stitch them together or calibrate a larger printer using my laptop or something. Are there any stratagies or tips for making sure I don't ruin the artwork and the scanner bed?
« Last Edit: April 20, 2010, 12:22:26 PM by adamlogan » Logged
adamlogan
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« Reply #16 on: April 22, 2010, 01:52:33 PM »
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So I am working on generating a scanner profile. I read about the diag check and figured it would not hurt. The output diag.tif has me a bit alarmed, the image of the lady is not actually supposed to be measured/used as if they were patches are they? I used the it8.cht from the argyll reference directory. I am using silverfast ai as that is what the labs provide. Made sure all settings I could find that might interfere are disabled. For my first try I used 48bit color, but I see that in the argyll documentation it mentions 8bit and 16bit, and does not mention any other values. 16 bit seems more than sufficient I suppose. However I don't see a straight forward way of choosing 16 bit color from the options. Would 48 bit >24 bit option work ok? If not would it be acceptable to reduce bit depth of target tif in photoshop before processing with scanin? It would be a shame to limit things to 8 bits.

I looked in the i1 case and found the i1 rgb 1.4 scanner test target so I am just gonna go ahead and continue reading the argyll documentation about using that test target for now.



[attachment=21662:diag.png]
[attachment=21663:bitoptions.png]
« Last Edit: April 22, 2010, 02:10:55 PM by adamlogan » Logged
MPatek
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« Reply #17 on: April 25, 2010, 03:14:04 PM »
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48->24bit is OK and can be simply set in SilverFast. That means you would be capturing 8bit per channel image, which is OK for profiling. Make sure that you set dpi between 150-300. Size of the captured IT8 target should be around 1.4MB-2MB. Argyll works fine with IT8 targets and you can always check which patches are read fine and where are problems.
I have described scanner profiling (using SilverFast and Argyll) at Scanning section of my web pages.
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adamlogan
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« Reply #18 on: May 12, 2010, 07:51:47 PM »
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Thanks. Was able to do scanner profiling fine with the i1 target.

I'm kinda lost with all the options when it comes to creating the printer profile. Used these flags:
colprof -v -D"epsonstyluspro4880a8bit" -qm -bnone epsonstyluspro4880a8bit

I printed out the small photodisc test image from drycreek to see how the profile is working and it looks terrible. Can't be sure if something is getting goofed up since I am printing with Adobe Photoshop CS4 on Snowleopard 10.58.. Am using Eric Chan's workaround (assigning adobe rgb to document color space, then color managing with photoshop and selecting adobe rgb again with rel colorimetric and black compensation off, disable color management in the proprietary print driver.)

With the print target I tried one print converting the document color space to the custom printer profile, used the same profile again with photoshop managing, and turned off color management in printer driver.

Then tried a second print leaving the color space of the document alone, and photoshop manages with custom profile relative colorimetric and black compensation on, and turned off color management in printer driver.

I think it's safe to assume I need to not use the -b flag and add others.. The problem is I simply don't want to have to specify a src profile as I will be using the custom printer profile from many different lab computers as the printers are networked and I can't always sit at the same workstation. I don't understand why using an arbitrary "reverse" colorspace like SWOP v2 would help if Photoshop will show transform conversion on the fly by softproof and the printing process.

Right now I am installing a windows xp virtual machine guest inside of VirtualBox. Going to try printing through that with Photoshop CS3 or CS4 and hopefully I can avoid hoping through all these loops and keep it less complicated.
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