tag:blogger.com,1999:blog-1840985738235902482.post3164578578799476712..comments2024-03-11T13:06:45.258-04:00Comments on John the Math Guy: What measurement condition is your spectro wearing?John Seymourhttp://www.blogger.com/profile/11350487038873935295noreply@blogger.comBlogger13125tag:blogger.com,1999:blog-1840985738235902482.post-41179363077224439092016-09-21T05:07:28.098-04:002016-09-21T05:07:28.098-04:00nice article, using great equipment to measure the...<br />nice article, using great equipment to measure the thickness of your paint will produce you with good information about your stuffs.<br /><br />regards,<br /><br /><a href="http://www.phillro.com.au/p/industrial-2/spray-guns-3/" rel="nofollow">Paint Spray Gun</a>seravina danniellahttps://www.blogger.com/profile/17416651554211077082noreply@blogger.comtag:blogger.com,1999:blog-1840985738235902482.post-56539212567443193342016-02-12T09:03:52.193-05:002016-02-12T09:03:52.193-05:00Thank you so much for the information generously p...Thank you so much for the information generously provided. I'm also "knee-deep" into M1 measurements. As I was reading your comments above about Coca-Cola, I could not help conclude that the problem with which numbers everyone in the supply chain gets (M0 type of numbers since that's still the majority of instruments anyone in the chain is still having access to) but this does nothing for managing the color appearance. In effect, as I read your note, Coca-Cola is effectively washing their hands of it. Meaning that, the visual results does not matter all that much to them, it is more important that everybody involved in the production of their prints get the "number" comparable -- never mind what the thing looks like. <br /><br />The other comment I want to make is the bogus claim that light from booths "shall" or "should" have a higher UV-content than before and, therefore, when M1 measurements (whatever that means) are used, visual appearance will correlate better with M1 measurements?<br /><br />It is true that, slowly but surely, as printers replace their aging pre-2009 fluorescent bulbs in their overhead luminaires, the new ones they get from GTI ("E" series) and JNL are supposed to have a higher UV content. There is the revised UV-Metamerism index that has to be calculated to prove conformance but who has instruments that are sensitive enough below 400nm to reliably measure the amount of UV? The EyeOnePro which most folks have at their disposal A) are insensitive in that part of the spectrum, and B) offer too wide of a bandwidth to be useful for ISO-3664:2009 measurements. <br /><br />So, who is actually checking the actual content of their overhead luminaire at press consoles? The FD-7 has an irradiance mode that seem to measure down to 360nm… I'm still unsure whether that's enough to do the test…<br /><br />So, where does that take us?<br /><br />Minolta FD-xx seems to be doing the right thing with its bi-spectral reflectance measurements but does that actually result in "true" D50-like illumination? I'm still not 100% clear on their technology but I suspect they're on to something that X-Rite is not…<br /><br />/ Roger Breton<br />www.graxx.caAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-1840985738235902482.post-40867751713334741562015-01-13T11:32:41.006-05:002015-01-13T11:32:41.006-05:00Thanks for the comment, Steve. An important questi...Thanks for the comment, Steve. An important question... do the fluorescent dyes have the same behavior (excitation and emission bands) as the stilbene used as an OBA in paper?John Seymourhttps://www.blogger.com/profile/11350487038873935295noreply@blogger.comtag:blogger.com,1999:blog-1840985738235902482.post-53348504192445808242015-01-12T20:28:31.486-05:002015-01-12T20:28:31.486-05:00It’s a common practice in folding carton packaging...It’s a common practice in folding carton packaging printing on SBS paperboard to have florescent dyes added to aqueous or UV coating so knockouts for glue flaps can be seen better under a black light for QC process control.<br /><br />Steve SuffolettoAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-1840985738235902482.post-79139288804904754332014-12-11T10:52:31.068-05:002014-12-11T10:52:31.068-05:00Alex,
Yes, a halogen bulb will out out some UV......Alex,<br /><br />Yes, a halogen bulb will out out some UV... hence the need for a UV cut filter on the pre-2009 instruments. Not a lot, and not as much as D65.<br /><br />Will your profiles be more accurate with M1? I can say that an M1 profile will do better at predicting the appearance of the pants in the stadium, if daylight is the main illuminant on the field. If the game is nighttime and being played under mercury vapor lights, then I don't know! <br /><br />Feel free to contact me at john@johnthemathguy.com if have more specific questions.John Seymourhttps://www.blogger.com/profile/11350487038873935295noreply@blogger.comtag:blogger.com,1999:blog-1840985738235902482.post-57627647731701649242014-12-09T20:37:33.200-05:002014-12-09T20:37:33.200-05:00John,
On the spectralight, the UV bulbs are not ...John, <br /><br />On the spectralight, the UV bulbs are not behind the D65 glass. <br /><br />I went back under the hood and noticed that there is a pair of long UV bulbs that activate only for the non-daylight settings, and then a separate skinny 8" bulb that comes on for the 'daylight' (D65). After looking up tungsten-halogen lamps (http://en.wikipedia.org/wiki/Halogen_lamp) it looks like these bulbs emit some UV anyway, so they might be adding the smaller UV lamp to supplement the halogen lamp's UV. Following that notion, I would conclude that the 'daylight' setting on the SPLIII is already exciting the optical brighteners which is why there is no significant toggle effect with the smaller UV bulb. <br /><br />The fabric definitely fluoresces under black light, but I've got my rep contacting the mill to confirm for OBAs.<br /><br />Aside from supply chain, my main focus is on understanding the color gamut and color accuracy of a D50 M1 spectro over an Illuminant A spectro. My 'tentative understanding' is that greater excitation of those optical brighteners with the D50 will feed more color data into my profile over a standard Illum.A spectro. Does getting a columbia blue to 'pop' more by having UV when profiling (M1) make for a better/wider/truer profile? Does that columbia blue sublimated football pant look better in a bowl game when profiled with M1 D50 spectro vs M0 Tungsten?<br /><br />Thanks for the links. I'm glad to have found this blog. <br /><br /><br /><br />Alexnoreply@blogger.comtag:blogger.com,1999:blog-1840985738235902482.post-7689064109517935472014-12-09T11:35:11.189-05:002014-12-09T11:35:11.189-05:00Alex, Thanks for the questions... you are learnin...Alex, Thanks for the questions... you are learning me about textiles!<br /><br />I am not sure why the UV toggle should have no effect under D65, but I have a guess. The UV cut filter will remove most all of the UV. If it is having no effect, then it must be that the D65 glass has already taken out all the UV. I am not sure why they would do that, or even if they did, but prior to 2009 with the definition of M1, there were no official requirements for "D65", so it would have been acceptable.<br /><br />Do fabrics have OBAs? Other than the fact that I wear clothes most every day, and the fact that I lived through the 60's and the black light phase with paintings of Elvis on black velvet, I don't have a lot of experience with OBAs and textiles. But I have heard from various reliable sources (or at least, people who have told me that they are reliable) that fabric often does have OBAs. I know for sure that most laundry detergents have "bluing agents", which are OBAs.<br /><br />In general, you have two choices: Either you a) go to M1 so that you have a chance for various make and model of spectros throughout your supply chain to work and for measurements to agree with visual assessment in a light booth, or b) make sure that all the instruments in your supply chain are the same make and model.<br />For more information, I direct you to my blog on measuring fluorescent materials:<br />http://johnthemathguy.blogspot.com/2014/11/measuring-fluorescent-inks.html<br /><br />As for the measurement issues raised by the fact that some textiles have texture, there are two solutions. One is to use a big aperture and/or to average multiple measurements, such as you have done. This will reduce the variability. Another option is to use a spherical instrument (also called d/8 or 8/d). Since this collects light that bounces off in all directions, it is less susceptible to this variation.<br /><br />On matte fabrics, I have seen that the two instruments will measure reasonably close. On fabrics that have some sheen to them, there is a difference even when you do averaging with the 45/0 instruments. The spherical instruments will read lighter in color, and will probably not correlated so well with what we see when we are measuring dark of richly color fabrics that have some sheen to them.<br /><br />For a bit more information her, I point you to another blog post:<br />http://johnthemathguy.blogspot.com/2014/10/a-guide-to-reflectance-measurement.html<br /><br />John Seymourhttps://www.blogger.com/profile/11350487038873935295noreply@blogger.comtag:blogger.com,1999:blog-1840985738235902482.post-82811768518450435142014-12-08T17:36:30.340-05:002014-12-08T17:36:30.340-05:00I've been shopping around for a spectro for dy...I've been shopping around for a spectro for dye sublimated apparel. I've been going between the Barbieri LFP (No M1) and Spectropad (M1). The latter has the newer tech but the former does a lot more (multiple aperture sizes, multiple patch reads) that works for meshes and different textures in fabric. I toss in some charts printed on poly/spandex fabric in our Spectralight III and the white glows under pure UV. In fluorescent illumination and Illuminant A, I toggle the UV and definitely notice the lighter/brighter colors reacting to the UV in those conditions. <br /><br />What's curious is that we have D65 glass in front of some halogen bulbs for 'daylight' illumination, and the UV toggle really doesn't have a effect when I toggle it under that condition. Is it because the D65 with Halogen already has UV in it?<br /><br />Are there FWA/OBA's in the fabric? I think so if its reacting to the UV in fluorescent light and Illuminant A. Which leads me to think I would be missing out without an M1 spectro.<br /><br />Any thoughts comments? I could use some insight since not much technical nitty gritty goes on regarding dye sub apparel. <br /><br />ThanksAlexnoreply@blogger.comtag:blogger.com,1999:blog-1840985738235902482.post-22440197878323694302014-12-03T12:27:34.416-05:002014-12-03T12:27:34.416-05:00Anonymous - You have pointed out the need for anot...Anonymous - You have pointed out the need for another use case: If viewing booths are not part of the workflow, and if the same make and model of spectro is used throughout the entire supply chain from designer to prepress to press to print buyer, then M0 will work fine, regardless of OBA content. Coca Cola has mandated just this.<br /><br />You said that M0 is very consistent... As I think we agree, there is an issue with the fact that viewing booths will excite the OBAs differently than an M0 instrument. You alluded to the fact that not all M0 instruments agree, but I am not sure that this is widely understood. So let me pontificate on that...<br /><br />ISO 13655 defines "M0", and recommends that the illumination look like an incandescent light bulb with color temperature of 2856K. But his is only a recommendation. The standard deliberately uses the word "should", rather than "shall".<br /><br />I recall this choice of words being deliberated at some length in standards meetings. In the end, M0 became the catch-all that allows continued use of any of the spectros currently being used. But, there are no mandatory requirements to qualify for M0.<br /><br />Is a white LED instrument compliant with M0? Yes. How about an instrument with a xenon strobe, which may put a lot of UV? Yes. An instrument that uses a bottle of fireflies for illumination? Yes. I have just filed a patent for the firefly design, so it must be a great idea.<br /><br />Next question... why weren't some mandatory requirements for M0 put into 13655? If virtually every handheld device (at the time) used a light bulb, then why couldn't the standard just require adherence to 2856K to within some tolerance?<br /><br />The answer is simple and practical. Different existing instruments that use an incandescent bulb had vastly different amounts of UV light.<br /><br />Why is there a variation in the amount of UV? There are a number of reasons why engineers may have made choices that effect the amount of UV.<br /><br />There are advantages and disadvantages to running a bulb above or below 2856K. Running it higher ("over voltage") gives you more light, especially at the blue end, and hence better noise characteristics, but it drastically shortens bulb life. So, different engineers made different tradeoffs. The higher the bulb temperature, the higher the ratio of UV light.<br /><br />Glass and some clear plastics absorb UV - it is hard to get a sunburn through a window. The number of pieces of glass/plastic and the thickness of them will alter the amount of UV.<br /><br />Incandescent light is weak at the blue end. Silicon detectors (which are in most if not all handheld devices) are also very insensitive at the blue end. Some spectros add a light cyan filter to dampen the red and somewhat dampen the green.<br /><br />And of course... when the latest revisions of 13655 were on the table, LEDs were just starting to be considered as a light source in spectros. White LEDS (as well as any other LEDs that provide visible light) put out virtually no UV. <br /><br />You said that M2 and M3 are not necessarily consistent between models. I am going to disagree and agree with that statement. M2 was envisioned to be the UV cut version - it requires virtually no OBA excitation. M3 requires M2 compliance as well as the polarizing filters. So I disagree.<br /><br />On the other hand, while there is a "shall" in the definition, it is a fuzzy "shall". It says: "[M2] shall only contain substantial radiation power in the wavelength range above 400 nm." There is no definition of what the word substantial means, and not explanation of how to test for this.<br /><br />Also, the standard indicates that measurement at 400 nm and 410 nm are desirable, so there must be light available at these wavelengths. This light will also excite the OBAs. So, I agree with your statement. <br /> John Seymourhttps://www.blogger.com/profile/11350487038873935295noreply@blogger.comtag:blogger.com,1999:blog-1840985738235902482.post-35750880753201375342014-12-03T08:34:57.593-05:002014-12-03T08:34:57.593-05:00John - I do not think that you make the point stro...John - I do not think that you make the point strongly enough that M0 and M2 are not equivalent. Thus M0 and M1 are not so incompatible as you state. Many converters and print buyers have been converting and buying print using M0 for a long time with good success. <br /><br />So if you happen to be measuring ink on paper, then you just gotta plunk your money down for an M1 instrument, because you will find your old M0 instrument disagreeable. It will disagree with your light booth, with M1 instruments, and even with M0 instruments from other families. The thing is that pretty much all paper for commercial printing will have OBAs added, so you have a choice as to whether to deal with a petulant teenager, so buy into the M1 craze<br /><br />The key to success in characterizing objects with fluorescent colorants is consistency. M0 is very consistent, if it is truly based on an incandescent lamp of known color temperature. The amount of UV to VIS in its spectrum can be predicted. Not so lucky with M2 or even M3 where the amount of radiance removed from the shorter wavelengths is a function of the optical system and materials. But, if you have viewing cabinets equipped with a lamps that produce a UV to VIS ratio that is in closer conformance to the D50 spectral power distirbution then M0 will consistently under excite the OBA and the radiance factor used to produce CIELAB values will have b* values that do not correlate well with the visual examination. The advantage of M1 is that it wil produce radiance factor curves and by tristimulus integration CIELAB coordinates that are more consistent with visual assessments according to ISO 3664.<br /><br />Case in point - how do you describe an instrument system with a white LED with a color temperature of 2850 K? Is this M0 or not?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1840985738235902482.post-85993071303730418902014-11-10T14:49:03.407-05:002014-11-10T14:49:03.407-05:00"Is this a plausible explanation?"
Coul..."Is this a plausible explanation?"<br /><br />Could be... but not in this situation.<br /><br />What I'm referring to is a (sometimes) startling difference between plugged shadows and shadows will lots of detail and differentiation. So the higher density is nice, but that would be available in either scenario. With M3 (pol) we get the higher density and the smoother tone range as well.<br /><br />Also, this is not just limited to glossy canvas - though that might be the most noticeable case. We've seen great results on simple watercolor papers such as Arches.<br /><br />My initial concern was not that the images would be richer than accurate, but in fact the opposite. I was thinking that the system would think for instance "wow, I can get really saturated browns. I'll need less ink to get the requested color" and it would appear unsaturated to the unpolarized viewer. In practice, however, it doesn't behave that way. It's something I don't have my head fully around yet. But it works.<br /><br />regards,<br /><br />Steve<br /><br />Steve Uptonhttps://www.blogger.com/profile/15008548505546991694noreply@blogger.comtag:blogger.com,1999:blog-1840985738235902482.post-11406612814050684132014-11-08T12:09:33.815-05:002014-11-08T12:09:33.815-05:00Hello Steve,
I'm glad that the blog is apprec...Hello Steve,<br /><br />I'm glad that the blog is appreciated. I also appreciate comments, especially from sharp people like yourself.<br /><br />Let me offer a possible explanation for what you have seen... feel free to tell me I am full of beans.<br /><br />On a glossy canvas, you can get very high densities, first, since it is glossy and there is little contamination with surface reflectance, and second, because it has surface texture which can trap some of the light. We also know that people tend to prefer images that are richer than real life... more saturated colors and higher densities. And of course, polarized spectros naturally give you higher densities and richer colors than non-polarized.<br /><br />Putting those two together, we have a substrate that is able to make a print that is preferable to the "correct" color, coupled with a measurement technology that "artificially" gives the profile more punch.<br /><br />Is this a plausible explanation?<br /><br />John<br /><br />John Seymourhttps://www.blogger.com/profile/11350487038873935295noreply@blogger.comtag:blogger.com,1999:blog-1840985738235902482.post-658957483373298382014-11-07T21:13:48.486-05:002014-11-07T21:13:48.486-05:00Hi John,
Another good post.
I have to differ on ...Hi John,<br /><br />Another good post.<br /><br />I have to differ on the use of M3 though. In building profiles for inkjet printers on water color papers, canvas (especially glossy canvas), and other specialty papers, M3 makes a HUGE difference.<br /><br />If the various surface reflections aren't knocked down then the profiles tend to lose a lot of detail in the shadows. Slap a polarizer on and suddenly you're getting "pro photographer" results instead of just good "color matches". It reminds me of the difference a good drum scanner could get out of a full-range transparency.<br /><br />And while soft-proofing using the profile is a bit optimistic in the density and saturation of dark colors, it's not too bad either. It still seems somewhat counter-intuitive to me but we've been building profiles for people around the world using this technique and the years of happy picky people have proven the point to me.<br /><br />regards,<br /><br />Steve Upton<br />Steve Uptonhttps://www.blogger.com/profile/15008548505546991694noreply@blogger.com