Instrument Spotlight iSis
Feed and Fly
A hand-held spectrophotometer is often the first foray into the world of color measurement. If you measure regularly, the repetitive sliding of the instrument can get old very quickly. Don't you wish you could just feed in a sheet of paper and the instrument would take it and read it while you go about your other business?!
XRite's i1 iSis 2 is a sheet reader which measures an entire sheet of color patches, rather than a single spot or a single line at a time. The standard model handles pages up to 9 inches wide, and an "XL" model can accommodate pages up to 13 inches wide. When it was first introduced in 2006, the name was intended to evoke the great productivity of the ancient Egyptian god.
A few extra requirements in chart design make for a consistently dependable spectrophotometer that will provide years of fast chart measuring, and can be used by even the most inexperienced operator on the press floor. We particularly like this instrument for its ability to quickly measure an entire sheet. Maxwell takes full advantage of such targets, providing cross-sheet variability heatmaps and virtually fool-proof operation when used with bar codes.
The DTP-70 was a sheet-reading predecessor of the iSis, built by X-Rite before they acquired GretagMacBeth and their iSis. It was loved by many who appreciated the ability to scan an entire sheet of patches at a time. The speed and accuracy of this instrument made it a favorite for those who measure a lot of targets. Unfortunately, the DTP-70 was rather finicky. If you did not feed in the sheet exactly right, it would spit out the paper without so much as a how-do-you-do or an explanation of why. It was sometimes exasperating to try to figure out what combination of trimming the sheet, crossing of fingers, and feeding it in "just so" was necessary to make it measure successfully.
The development of the iSis introduced a sheet-reader that could be used by the average Joe on the production floor (and included a wider model for larger sheets). Although it does come with stringent target layout requirements, once a target is made to those specifications, it can measure targets quite easily and dependably.
Stringent target specifications allow the iSis to reliably and forgivingly measure a variety of media types. The iSis requires a row of black diamonds ("alignment marks") on the left and right margins of the paper to help track the measurement of the patch rows past the measurement head. Other specifications, such as the inclusion of a black bar across the top of the page, and extra space along the leading edge of the page, allow the machine to be more forgiving of any feeding errors. Even a sheet that is fed in a bit crooked can be measured successfully.
The target-definition reference file requires that several specific data be defined, having to do with these page layout parameters. Any software that creates charts for the iSis will do all this calculation for you, so you don't need to know the details. But it is good to know that you will have to devote some real estate on your press sheet, some "wasted space" that does not include patches, in order to create iSis charts. Software that drives the iSis will accommodate multiple sheets, so profiling targets with high patch counts can be measured easily.
While the iSis is not as finicky as its predecessor, these layout requirements are essential- for example, if you crop off alignment marks or scale a chart down, you will likely have measurement errors or no measurement at all. The chart must not differ from the size specified by more than 8%.
X-Rite offers a choice between creating charts with a standard margin for alignment marks and "tight margins" to accommodate those who want to make the most of the space on their crowded press sheets. Finally, there are limitations about material that can be used. This instrument expects the media to have some flexibility, and does not support rigid material like aluminum sheets. The thickness of the media should not exceed 0.45 mm. This will not be a problem for most of the common papers that are used in printing, but those wanting to measure thin poly or textiles will need to look to a table like the iO or Barbieri LFP.
The first generation of iSis measured in M0 (unfiltered illuminant A) and M2 (UV-filtered) modes. The current generation (i1 iSis 2) handles M0, M1 and M2. See here for more information about measurement modes.
The iSis is hands-down faster than any hand-held measurement instrument. It is often purchased by customers who tire of measuring 2000+ patch targets using hand-held instruments. Even if the patch count requires multiple pages, the time spent interacting with this instrument is minimal. You feed in the sheet, the machine takes over, scans the sheet and automatically ejects it when done. There is not much of anything that can go wrong while measuring, and it is fast. The published specs for speed are 1500 patches in 8 minutes. In my tests I found that I can measure a 900 patch sheet in about 5.7 minutes (M0). The only other instrument we know that can top the iSis in measurement speed is KonicaMinolta's FD-9. (Review of the FD-9)
The published spec for this instrument indicates that repeatability is .10 dE*94. Agreement between different iSis instruments is .40 dE*94. This is a much lower number than with the i1Pro 3 (Reviewed here). A lower dE number means that this instrument is very consistent in its measurements time after time. While the X-Rite marketing department would probably not appreciate the term, the i1Pros are considered "consumer-grade", while the i1 iSis 2 is positioned as a significant step up in quality. A glance at the repeatability and inter-instrument agreement numbers for the i1Pro and the iSis shows much lower numbers for the iSis.
At CHROMiX, accuracy is of critical importance in our Maxwell service. The difference between a company's press being okay to run or being out of tolerance can be a fraction of 1 dE. While this instrument allows a minimum patch size as small as 6 mm, we have found that using larger patch sizes can improve accuracy and consistency in the measurements. Giving the instrument a larger patch to read gives it more information to work with, gives it more samples to use. For typical profiling purposes, the average patch sizes will do nicely, but when an extra level of accuracy is desired, such as in daily mission-critical color verification of high-volume presses, larger patches are a good practice. We often recommend going as high as 12 mm (almost 1/2 inch) in order to get a good balance between high accuracy and efficiency.
X-Rite supplies the i1Profiler software, which allows the user to create charts specifically for the iSis, measure the charts, and create profiles from the measurements. Profile creation options vary according to the licensing that one has purchased for the i1Profiler software. The basic chart creation and measuring functions are freely available with the unlicensed version of i1Profiler.
ColorLogic's Zepra and ColorAnt software also support the iSis and produce profiling targets with the required markings.
Numerous RIPs support the iSis. These provide linearization, calibration and profiling charts laid out with the specific iSis requirements, and will directly drive the instrument from within their RIP software.
CHROMiX and Don Hutcheson produce the Curve4 software that supports iSis measuring when doing G7 calibrations and verifications. We find our measurement module connects to instruments easily, has many time-saving settings, and is more intuitive than other options.
Maxwell customers can use the same measurement dialog window that may be familiar from Curve4. All the same advantages of the Curve4 measurement module are included in the Maxwell Client, as well as new features making full use of the iSis' ability.
Barcodes and Autorouting
The iSis chart can optionally include a bar code strip which encodes information about the chart layout as well as user-specified text. The barcode allows the iSis to determine the chart layout right on the chart, helping measuring software to find and choose the correct target definition file.
CHROMiX makes great use of these barcodes in Maxwell. With our Autorouting feature, in addition to encoding the chart layout information, the bar code also identifies the specific Maxwell Track the measurement is to be routed to. Together, this makes for a virtually foolproof way for operators to submit measurements into Maxwell. Targets from different presses can be fed into an iSis running on the Maxwell Client, and the system automatically measures the target & routes the results to the appropriate Track in Maxwell. You basically feed it in and walk away.
The Barcode Tool in the Maxwell Client is available to create barcodes and impose them onto existing iSis target image files. We create targets with customized barcodes for customers, and some of them use the tool themselves to create their own targets for use in Maxwell.
Cross-Sheet Variation and Heat Maps
The ability of the i1 iSis 2 XL model to accommodate a wide page width of 13 inches makes this instrument ideal for measuring cross sheet variation for modern digital presses. Liquid and dry toner-based presses have issues printing consistent color across the entire width of the printing path. Since many of these presses have a 12 inch print path, Maxwell users can print and measure a full-page chart using an iSis, and view a revealing "heat map" of the location of errors across the sheet.
The iSis is typically connected to a computer using a mini-USB cable. X-Rite also offers an "iSis NET" model which can also connect through an Ethernet cable. When USB-connected it behaves as a normal iSis but when connected to Ethernet it becomes a stand-alone tool allowing measuring and local storage of scans. Charts for the iSis NET require a particular flavor of bar code that allows software on the network to retrieve measurements.
There is no wireless connection option with either of the two iSis models.
A couple of things worth mentioning are the shipping lock, power light, and top cover. On the bottom of the iSis is a small sliding switch that locks the iSis measuring head in place for travel. It's wise to engage it before moving the iSis anywhere that might involve jostling and even wiser to remember to unlock it before powering the iSis up - the grinding noise is alarming!
And speaking of power, the iSis has an idiosyncrasy where the power light will not glow unless the iSis is also connected by USB to a computer. So if you plug one in to power and turn it on, don't panic if you don't see any power light. Attach it to your computer and the power light will glow. (There was an incident before a trade show that we wouldn't want you to have to repeat.)
Finally, though the top cover for the iSis is locked closed when shipped, it can be opened. For most scenarios leaving it locked is probably best so users don't poke around inside and dust and dirt don't enter. But it can be popped open with a flat blade (we suggest plastic to avoid scratching) inserted in the front crack and then twisted. Once unlocked you can easily open the top to see why you might be having paper feed issues, etc.
The iSis is a real work-horse in this industry for those who need a high-quality, speedy way to measure an entire sheet of paper at a time. This is an obvious step up in quality, speed and convenience from the i1Pro instrument. For flat, thin to medium weight papers, this instrument is a dream to work with. The family of iSis models has been providing robust service in all parts of this industry for over 14 years, so you also get the dependability of an instrument that has been well tested over time. In a year where many of us have rhetorically asked "What else could go wrong"? only to find more trouble around the corner, the year 2020 might be the time to invest in an instrument that will dependably make your life better.
See the iSis in action using CHROMiX software in this 3-minute video
Thanks for reading,