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Any Graphics professionals out there?

Discussion in 'Desktop & Laptop Computers Forum' started by Dr Nick Riviera, Jul 16, 2004.

  1. Dr Nick Riviera

    Dr Nick Riviera
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    I work in reprographics and want to switch to TFT for my next Apple G5 workstation. Despite all the individual claims from manufacturers, can anyone out there who uses a high end TFT with standard mac apps like Photoshop, Quark, Illustrator etc etc comment on just how accurate they are on grayscale, CMYK and Pantone reproduction?
    I am considering one out of these:
    LaCie Photon 20.1" 1600x1200
    Eizo ColorEdge CG21 1600x1200
    Eizo Flexscan L885 1600x1200
    Formac Gallery 2010 1600x1200

    Of these, the ColorEdge is by far and way the most expensive, and the Formac seems the "cheapest". PcPro rate the Flexscan 885 as the best 21" TFT in their A-List; also I've seen the LaCie performing well in some brief reviews.

    To clarify a little, I am not doing REALLY high end mission critical colour correction, but I do need to be able to colour correct to a pretty reasonable standard and also see realistic representation of Pantone colours and CMYK images within Quark 6, InDesign CS, Photoshop CS etc. I prefer to work at 1600x1200.

    If anyone with any experience could take a minute to comment, I would be grateful.

    Nick
     
  2. Mr.D

    Mr.D
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    I do digital effects work for feature films.
    We have currently just managed to buy up the last reserves of sony CRT workstation monitors as we have not been able to find an adequate digital panel replacement. Sony are supposed to show me a 4K (4096x3112) tft panel at some point but even then I doubt it will have the intensity range we require for film grading work.

    Colour accuracy is very critical for what we do though.
     
  3. ancientgeek

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    Not really my area, but Apple are always very careful to make their panels show accurate colours. Their prices are not unreasonable. They claim their screens are the only LCD's SWOP certified for soft proofing (www.swop.org). You can read something about it on the Apple web site. There's a 25 page PDF you can download.
    http://www.apple.com/displays/technology.html

    You need to calibrate the display of course and establish appropriate ambient lighting. I think the good colour accuracy goes along with the slightly reduced brightness Apple claim compared to others using the same glass. And of course your G5 will come with a Colorsync profile for the Apple screens.

    By far the biggest issue for colour accuracy of LCDs is change of colour with viewing angle.
     
  4. tomson

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    I'm currently using a Formac tft for web, photographic and print work and have just, this morning, been talking to colour management specialist about calibration for it. Basically if you take the time to set-up your monitor correctly using a hardware solution then you should get a pretty accurate representation of colours on the Lacie and the Formac you mention above (not sure about the others as those never came up). There are a few good options out there depending on budget (from the Spyder Pro to the GretagMacbeth etc) that will do the job to a very high standard.
     
  5. Dr Nick Riviera

    Dr Nick Riviera
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    Thanks all.
    tomson - are you going to go with a hardware calibrator? I looked at the Gretag and the Spyder Pro websites when I was scouring around, and they all seem pretty much the same. My issue is that I'd like a solution where I can print a sample test IT8 (or similar) sheet on our Print Press itself to standard densities, and then calibrate the screen accordingly to that, not the other way around.
    Any thoughts?
     
  6. tomson

    tomson
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    hmmm...assuming your print press is calibrated correctly (ie a pantone colour printed from it exactly matches the same colour in your pantone swatch guide) then it should just be a case of calibrating the monitor to follow suit. Surely?

    I'm probably going to go with the Spyder Pro as I've heard a lot of good things about it - apparently it does use old technology but is perfectly adept at calibrating both crt and tft displays to a pretty accutate level - and the price is very reasonable.
     
  7. Dr Nick Riviera

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    Sounds as though it should be easy doesn't it?!
    As i understand the process, it goes thus:
    1. We print a specially made output sheet to euro densities.
    2. Measurements are taken from this sheet via spectrophotometer.
    3. A profile is generated based on comparison of these measured readings against the acutal colour readings from the test sheet supplier.
    4. This profile can be implemented in digital proofing units.

    But what I'm vague on is the next stage: how is the colour calibration of your monitor done? Apart from some very high end monitors, it doesn't seem possible to actually adjust individual RGB/CMYK hues. As I understand it, the only thing that can be done is adopting the profile made earlier into colorsync as the system default, and is some cases, adjustment tot he color temperature.

    Does that sound right?
     
  8. Mr.D

    Mr.D
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    The trick is knowing what the display device is doing.
    The way to do this is to profile the RGB intensity response of your display in conjunction with your graphics card ie the end to end result.

    Once you know the response characteristics of the system you then do two things.

    Calibrate the monitor hardware to be as healthy as possible with regard to displaying a given set of chromaticity criteria ( doesn't really matter what primaries you aim for as long as the monitor can meet the aims reliably....not all monitors can unfortunately which is where I have my doubts about the digital panels)

    Now that you have the system performing to known parameters and you have a profiled LUT of the system response curve you can generate tailored LUTs that effectively take your system to the color standards you require)

    There are limitations to this. The hardware may not be capable of adequately displaying certain standards even with calibration: you are fundamentally limited by what the hardware can achieve.
    The achievable gamut from a given display is also a limitation and normally a little bit of fudging goes on to leave you with a display that is somewhat accurate across the majority of the intesity range but may well be off in certain areas purely because the display itself is just incapable of rendering certain colour values.

    One method of improving this is to use 3d colour models as opposed to 2d when generating the luts but I only know of a couple of commercial calibration systems that use this ( rising sun is one I think) but its fairly pricey last time I checked.

    After a while you begin to develop a sense of what your calibrated display is telling you verses the final result and you subconciously tailor what you see on your display a little to give the required result on your final medium.

    Certain standards are easier to get than others : film is very difficult and requires information normally quite closely guarded by the film manufacturers ( Kodak and Fuji pretty much) although rough models can be generated from test patterns if you know what you are doing.
    Video is actually fairly easy ( as its effectively a display standard) as long as you have decent kit.

    Print again is a little more complex although the standardisation of dyes will help somewhat you still have to deal with a mechanical print chain at the end of the day which is hopefully trying to do the same thing as your display.

    The best way is to calibrate with regard to your entire image pipeling : scanners , workstations , printers all calibrated to known aims which is fine if you have all those facilities under one roof.
     
  9. tomson

    tomson
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    If you buy something like the SpyderPro you'll get a piece of software called OptiCAL - this allows you to adjust your monitors R, G and B settings, your white balance and your gamma settings. The Gretag MacBeth Eye-one also has a similar piece of software included (but i've been told its less feature rich). Theres also a Monaco product for about a similar price.

    These are all low-end products though so don't expect miracles. But saying that i've worked in several design companies who use them as their main monitor calibration tool and when coupled with a well set-up and calibrated printer produce very accurate results. If your printer is outputting correctly then calibrating your monitor correctly to ensure an accurate screen to finished print should be fairly straight forward. If the printer isn't outputting correctly then thats a different matter all together.
     
  10. Dr Nick Riviera

    Dr Nick Riviera
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    Keith - thanks much for your input. It is clear that the highest of fidelity in terms of colour is not within our reach (or budget I might add) as a small commercial printer. We are just starting out on the mythical path of calibration and i think small steps are the order of the day for us!!
    tomson - I know the exact ink densities that our print press is running to at over 90% of the time - they are basically Euro Standard values. Therefore I can count on the print output from the press as my "baseline" constant and work from there. What i am still unclear on is how the data from the press is used to calibrate on-screen performance??
    Would the mentioned products such as SpyderPro be able to adopt a profile generated from the reproduction of the test sheet I mentioned earlier? The supplier of this test sheet has the measured values for all the multiple swatches on the file and simply compares your best printed effort (at standard ink densities) to those figures, in order to produce a profile curve for your digital proofer so it better matches the final printed output.
    When you say you can use the Spyder Pro (or similar) to calibrate your monitor, are you calibrating it AGAINST something, or just setting a neutral baseline in the environment it's in (ie ambient light etc etc)?
    Sorry to drone on but I've got to get the grey matter around this before asking for the money from the board.....

    Nick
     
  11. tomson

    tomson
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    I think theres some confusion. The products mentioned above are purely for calibrating a monitor to a known constant - so, at a very basic level, the software will display a colour on screen and the hardware will 'read' the colour and know if its displaying correctly. (Think of it as picking, say Pantone Process Magenta in illustrator and applying it to a shape. That Pantone colour is a known constant - take the file to a (good) printer and it should come out as its displayed in any Pantone swatch guide.) So, If the hardware reads that the monitor is not displaying the colour correctly (too much red, for example) then the software can adjust the display accordingly.

    If you want to include your printer in the calibration process then you really need to be looking at diffferent solutions. I know there is a Spyder package that includes a small scanner that scans a printed document and brings the printer into the calibration proces but my knowledge of this part of things is pretty poor i'm afraid.

    A bit of light reading:
    http://www.drycreekphoto.com/Learn/monitor_calibration.htm
    http://trikuare.cx/art/tut/gamma/
    http://www.normankoren.com/makingfineprints1A.html
     
  12. Mr.D

    Mr.D
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    There are really two ways of calibrating a system.
    You adjust the hardware to known aims ( ie calibrate the monitor) and apply standardised software LUTs ( look up tables) that are designed to bring a display of an assumed calibration to a correct standard. You have effectively setup your display chain to a baseline.

    This has the advantage of being a simpler less time consuming calibration that only requires measuring of the monitor at a couple of points on its intensity range ( it can even be done manually with a color analyser rather than an auto-calibrating system)

    Periodically as the monitor ages the calibration is done again to bring the monitor into spec until the monitor ages to the extent that it can no longer physically meet the desired white point and you require a fresh monitor . The LUTs used to reach whatever standards you require are never modified. This is probably what most low end calibration systems do.


    A profiled calibration is usually 2 stage and starts with a hardware calibration of the monitor ( similar to above) to maximise the available useful intensity range of the monitor ( with very few exceptions a decent CRT monitor will have a more than adequate intensity response to allow representation of most colour standards for a significant period of time . Digital displays tend to have a much more limited intensity range which is the main reason we don't use them .. we simply can't.

    Once the monitor has been optimised on the hardware side it gets profiled : a range of RGB patches (255patches is normally about the max required for most display systems even if the chain is higher than 8bit). The patches are read off the screen using a sensor and this plots the intensity profile of the monitor. This profile is then used to generate custom LUTs that apply solely to that system and again the end result of applying these LUTs is to give you a very accurate representation of a given colour standard.

    So you can see that a profiled calibration is a far more accurate system than the baseline method.
    However CRTs normally have a quite well behaved response curve (workling CRTs tend to exhibit a fairly consistent response curve) so you may well find that depending on the monitor the idealised LUT method is sufficient for a time and additionally if the required colour standard is reasonably simple a profiled calibration may be overkill. As monitors age they tend to develop nonlinearity and a profiled system will correct for this whereas a baseline system won't as it never really looks at what the moniotr is doing beyond colour temperature and intensity at a acouple of points.

    The LUTs themself can be applied either in software or loaded into the graphics card hardware on certain systems ( this used to be an issue a few years ago as running an 8 or even 16bit RGB LUT ( which is effectiley a realtime colour correction operation) is quite processor intensive. Once you get into 3d colourspace mappings it can be very intensive even on todays workstations.

    Bringing the print stage into the calibration loop could be done in a couple of ways : the printer itself could be profiled ( by printing out a test pattern and measuring it with a densitometer and effectively generating a lut for the printer and applying it back to the printer : or by mapping the printer lut back to the workstation , this would involve some compromising to give a somewhat meaningful application because of the differences in gammut between video and print and the whole viewing enviroment.

    Assuming you have the workstation operating with some accuracy to a desired standard post calibration you really want the printer to be accurate to the same standard then its just a question of how accurate is accurate! (you'll never get it 100% just because of the fundamentally different mediums : if anyone ever claims they have 100% accuracy its blurb!)

    Accuracy itself is all very well but predictability and consistency are important . ( the whole accuracy thing only comes into play if you created something on your workstation to a supposed standard adn had to print out on someone elses printer of the supposed same standard: you might get good results on your own hardware but less so on the outside kit as it may have been calibrated less accurately or slightly differently or may be intrinsically less capable of performing to accurate aims.
     
  13. CrispyXUK

    CrispyXUK
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    still, it will never be 100% accurate but you can get close
     
  14. Dr Nick Riviera

    Dr Nick Riviera
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    Keith
    Thanks again for your input - it's obvious you know this stuff! Reading through your post I think (although the Red Stripe is beginning to kick in now I'll admit) there are some useful parallels with my proposed situation:
    I have three devices in-house: a commercial cmyk lithographic printing press that is running to Euro standard ink densities, a high resolution Epson 7600 Pro proofer, and my proposed monitor (whether it be CRT or TFT).
    The hardware supplier (AGFA) is prepared to bring down their Spectrophotometer and an industry standard IT8 test file, run it through the press to Euro Standard densities, measure the values of predetermined swatches on that IT8 file, and generate a profile that can be applied back into the Epson 7600, so that the 7600 will produce proofs that accurately match the final printed output when run through the press. I get that.
    What I don't get is where (and how) to bring my monitor into this chain so that, for instance, when I open a cmyk tiff file on screen for evaluation, it matches as close as is possible (given the limitations you already mentioned such as visible gamut and the difference between transmitted light and reflected light to the naked eye) to the digital and lithographic outputs.
    Sorry if I am repeating myself here.
    Nick
     
  15. Mr.D

    Mr.D
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    It will depend on the calibration system and the capabilities of your equipment.
    If you have a closed loop system you'll be able to calibrate all the elements in your image pipeline with relevance to each other.

    ie: the profile of your printer , your monitor and your desired standard will all take reference of each other to give you the most accurate rendition of your chosen colourspace at each stage of the pipeline.

    From what you've said your printer is now calibrated to a known print standard . What you need to do is get your workstation calibrated and displaying the same standard ( in absence of a closed loop system) that means you'll have to hope your workstation is somewhat accurately calibrated and your printer is somewhat accurate if they are both aiming for the same standard.

    In your case find out exactly what the standard is on your printer and find a calibration system that will apply that standard to your workstation: assuming its compatable with your hardware and your hardware is actually capable of representing the colourspace with some accuracy and relevance.

    The Rising Sun system I mentioned doesn't support print standards as far as I'm aware. Its in the region of £1000 for the system. There are cheaper systems out there ( Lacie blue-eye I seem to recall being ok for certain standards)
     

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