RGB Printer Profiling with i1 Profiler

Over the past few months I’ve been one of the team beta testing the new X-Rite i1 Profiler software, and now that it’s been officially released I can begin a series of blogs taking you through the new software. We’ll start with RGB printer profiling, in my tests the new software produces profiles that are noticeably better in many areas than i1 Match, ProfileMaker or Monaco Profiler. Also for users of i1 Match the new software includes advanced functionality previous only available in ProfileMaker or Profiler, but before we delve into the RGB printer profiling workflow it’s worth saying a few things about the general interface.

The opening screen or page of the software has several useful features including the ability to automatically check for software updates, access information about the software online and most important of all access training videos. One of my standard pieces of support advice is RTFM - Read The Flippin’ Manual. I’m sorry, but having written software manuals in the past I’m one of those people that reads the supplied manual for whatever they buy, it usually saves me a lot of time and lets me find features that might remain hidden if I didn’t know they were there. However, I realise not everybody gets on well with software manuals, apart from maybe as a cure for insomnia, so what I suggest is that the first time you open i1 Profiler you have a cup of coffee to hand and sit back and watch the training videos supplied via the handy button on the screen. They cover most of the functions of the software and are clear and very easy to understand.

i1 Profiler has two modes, Basic and Advanced. The Advanced mode really comes into its own when you’re profiling CMYK printers and for a lot of users doing just RGB printer profiling using the Basic mode will just stop you being presented with options that you’d always leave to default anyway, but in the interest of full disclosure I’ll write the rest of the blog assuming you are going to use the Advanced mode.

i1 Profiler uses a a step by step process and the options for each page can be saved into a workflow. Default workflows are supplied but you can also save your own to suit your own kit or processes. A workflow can include options such as the number of patches, page size and profile settings. Saved workflows, previous profiles and other saved data can be dragged and dropped onto the buttons in a workflow to set the options.

The first page, Patch Set, in an RGB printer profiling workflow defines the number of patches you want to measure. You can measure as few as 400 or up to 6000. In my experience you get little benefit from measuring over 1000 patches for an RGB printer profile. You have the option of scrambling or randomizing the order of the patches just in case there is any difference across the sheet, but there shouldn’t be on a inkjet printer. Once you have selected the number of patches you can then move on to the next page, Test Chart.

The Test Chart page allows you to define what measuring instrument you are using, the page size of your printer and other physical options relating to how the chart is laid out. You might have to step back and forth between Patch Set and Test Chart until you find a number of patches that fit on a certain number of pages. Personally, I think it would be better if they combined the Patch Set and Test Chart pages so you could define the page size and instrument then click a button to fill the page with patches. Anyway, once you have define the parameters you can then print the target or save it as a TIFF file.

The Measurement page is obviously where you connect your measuring device and measure the colours, and pretty much does what it says in a similar way to other profiling software. The next page, Lighting, is a new option that will be unfamiliar to users of i1 Match. Printer profiles can be built based on an expected viewing light to help improve the accuracy of the profile under that lighting condition. For example, if you were producing prints for a gallery that had a particular type of lights you could measure those lights and then use that measurement data when the profile was created to make the prints look good under that light source. Usually, however, you don’t know where the print will be viewed so the best thing for the vast majority of users is to leave the lighting options set to the default of D50 and skip the Lighting page.

Profile Settings also allows a lot of control over areas that most users will leave to default. The perceptual mapping options allow you to increase or decrease Contrast or Saturation and also the Neutralize gray option allows you to choose if gray colours are mapped relative to the colour of the paper or more absolutely neutral. The effect of these options will only be visible when printing with the perceptual rendering intent and I’d recommend first building a profile with the default options (all to zero) before changing anything. The effects are subtle but can be quite pleasing. The Tables option govern the size of the tables within the profile, again there isn’t much need to deviate from the defaults. By the way the defaults are displayed as ‘Custom’ for some reason - one of the issues I reported back during testing they didn’t have time to fix. Advanced sets other options most users won’t touch, you can find out what any option means by activating the Help function by clicking on the question mark at the bottom left of the screen and putting the cursor over the item you want explained.

The final ICC Profile page lets you save the profile. A 3D gamut graph of the profile is then displayed. You should then go and test the profile by outputting a few files before trying the new profile optimization and verification options, but more about those in the next blog.

If you want to test the quality of the profiles from the new software then we’ve already swapped our custom profiling service (http://www.nativedigital.com/products/Custom-ICC-Printer-Profile.html) over to using the new software.

Creating the Right Ambience

I have a confession, I’ve never really got why you should compensate for ambient light when calibrating and profiling monitors. Don’t get me wrong I understand the principles and the effect that ambient light can have on the images you see on your screen, it’s just that to me making your monitor brighter or darker based on the light surrounding it is the wrong way round. Isn’t it better to get your ambient lighting to the right level so the monitor looks its best?

My first experience of colour correction came when I was working in a pre-press company and our drum scanning suite was housed in a former funeral parlour. Windows were few and far between and you can imagine that the lighting was on the sepulchral side, especially during the night shift. My current office has a large window but as soon as I do any image correction or software testing down comes the venetian blind to make the lighting as dim as I can. When I go on site to retouchers or video editing suites the light is also very low. My standard advice is that if the monitor is the brightest light source then your eyes will adjust to it correctly. Some customers say they haven’t got control over ambient light and I can imagine that in an office environment but for all our amateur customers most spare room digital photo studios are surely equipped with a light switch and a set of curtains.

I think the problem is that I know enough about monitors and print viewing to know not to hold a print next to my screen and expect it to match exactly. If I want to get closer agreement between the two I break out the viewing booth and adjust my monitor calibration targets to get a visual match but I usually take my prints to the window and view them in daylight and I find when I allow my eyes to adjust properly to either daylight or the monitor then what I see on screen is close enough to what I get out of the printer. So my only aim for the ambient lighting around my monitor is for it to be dim enough for me to see all the details in my images, especially in the shadows, so for that the room lighting has to be very dim.

Anyway, I’ve just started beta testing a new monitor calibration solution and amongst the first few screens in the software is the ability to measure ambient light and adjust the calibration targets accordingly. The developers were making a big song and dance about it so I thought I better revisit the area of ambient light compensation to see if I was missing something.

Our biggest selling monitor calibration and profiling solution is the i1 Display 2 from X-Rite. It’s philosophy dove tails with my own view on ambient lighting in that it does allow the measuring of ambient light but it is for information only and doesn’t suggest calibration targets, affect the calibration or monitor ambient light and adjust the monitor on an ongoing basis.

I connected my i1 Display 2 and launched i1 Match. I checked the Ambient Light Check option and then closed my blinds as I usually do when I work on images. I clicked measure and found that at 28 lux it thought my lighting was too dim so I opened the blades on the blind slightly and remeasured until the black line was in the central green area. The room was still acceptably dim but not quite as dark at 53 lux. After calibrating the monitor to 120cd/m2, 2.2 and 6500K (my usual targets) I examined my Square Black Level Test image that has concentric areas of very low RGB values. I could not see much variation in the blacks but if I closed the blinds completely again then I could see all the values distinctly. The recommended values for ambient light in the i1 Match software are based on the ISO 3664 standard although another ISO standard, ISO 12646, recommends lower levels of light, such as I normally have.

The Spyder3 Elite software does have more ambient lighting features. During the calibration process it can measure the ambient light and suggest new calibration targets. The Spyder Utility can also be set to monitor ambient light and warn you if it begins to differ too greatly. The first half of this article was written in the late afternoon when the sun had gone around the side of our building. This second half on the Spyder I’m writing in the morning with the spring sun shining on the window. I have the blind fully closed but it is still much brighter than yesterday, i1 Match says 182 Lux.

Running the ambient light analysis as I calibrate the monitor using Spyder3 Elite it suggests a luminance level of 200cd/m2 and that is much higher than my normal 120cd/m2 target. It reports the lighting level as Very High. It is brighter than yesterday but I wouldn’t really say it was very bright, it’s still dimmer than most offices. I accepted the Spyder’s recommendation and calibrated the monitor. It was much brighter than I’m used too and looking at images in Photoshop both before and after I preferred my normal luminance level. I couldn’t see the shadow detail on my Square Black Level Test image even with the monitor set brighter than normal. I turned on the ambient light monitoring in the Spyder utility and after a short while the little icon turned red and when I went into the utility it said the ambient lighting was now just High and I should recalibrate or return the ambient lighting to the condition it was when I calibrated. I hadn’t opened the blind or anything, the sun must have gone in or moved around the building a little.

If I was a photographer wanting to process some RAW images I would now have the quandary of wondering wether to wait for a cloudy day, recalibrate every time the weather changes or, I suppose, buy a proper black-out blind.

Constant recalibration would mean the images I see on my monitor would always be changing and I think I still prefer to stick to the same calibration targets over time. Obviously you can’t always choose when you process your files. So, of the three choices the black-out blind makes the most sense to me. If you can block all light coming in from outside you could control the lighting level more precisely, all though of course you’d have to choose any artificial lighting carefully for the intensity, colour temperature and colour rendering index. Many of us started our photography by working in a darkroom and I think for many it still makes sense to work in one now.

Discussing the Discus

I’ve finally managed to get my hands on a BasICColor DIscus, ours came today just in time for us to show at Focus. The BasICColor DIscus has been designed to be the best monitor calibrator on the market, and barring lab grade instruments, I think it probably is. So far, because all our test monitors are packed up for Focus, I’ve only got to test it on my new MacBook Pro but even with a relatively poor quality screen it’s given an excellent calibration.

The Discus has been designed from the ground up to cope with any kind of display or projector, even difficult LED back lit ones, and to deliver extremely high levels of consistency and repeatability. True it’s not the prettiest of products, but the best ones seldom are. Most colorimeters on the market are necessarily compromised by the need to get to a price point that most customers feel able to pay. The more expensive Spectrophotometers can be more accurate but don’t measure dark blacks very well. The Discus was designed to do the best calibration including dark black levels, for the widest possible range of screens, hence it isn’t cheap at just under £700.

basICColor Discus shown on NEC SpectraView monitor.

It does though have a host of unique features that could make it worth the money to the right kind of customer. It can measure monitors from a distance to account for the way ambient light affects the display, it has a built-in laser for accurate aiming. As new display technologies come to market the Discus can have it’s firmware updated to account for the difference in gamut and backlighting. Each Discus is individually calibrated in the factory and can be re-certified at any time and it has a temperature sensor to compensate for variation during measurement. Also it is already compatible with SpectraView Profiler or can be used with BasICColor’s own Display software.

For those customers who need absolute precision in monitor calibration this precision made German instrument is the answer. Come along to stand K3 at Focus on Imaging at the NEC from Sunday 6th March and see for yourself.

Rob Griffith