{"id":567,"date":"2015-12-21T20:00:43","date_gmt":"2015-12-22T01:00:43","guid":{"rendered":"https:\/\/designinglight.com\/?p=567"},"modified":"2015-12-22T20:52:32","modified_gmt":"2015-12-23T01:52:32","slug":"nema-misrepresents-ies-tm-30","status":"publish","type":"post","link":"https:\/\/designinglight.com\/?p=567","title":{"rendered":"NEMA Misrepresents IES TM-30"},"content":{"rendered":"

On November 12 the National Electrical Manufacturers Association (NEMA) published a position paper on IES TM-30-15. The document is here<\/a>. It seems to be a willful misunderstanding and misrepresentation of TM-30. Here\u2019s how\u2026<\/p>\n

The paper opens with NEMA\u2019s support of an improved color metric but then goes on to say that \u201cNEMA opposes any mandatory reporting or performance requirements for IES-Rf or IES-Rg.\u201d This is a strange opening since neither the IES, in general, or TM-30, in specific, is proposing mandatory requirements. In fact, the IES\u2019s own position paper<\/a> on this states that \u201cAs with any IES Technical Memorandum, TM-30-15 is not a required standard.\u201d So the paper begins with alarm about a non-issue.<\/p>\n

Next, it says that, \u201cAny single-number fidelity measure (such as Ra or the new Rf) that averages the results of many colors in a light source could possibly have a high numerical value and yet perform poorly with some specific colors.\u201d Exactly. That\u2019s the problem with CRI Ra, only a single number is reported. The great advantage of TM-30 is that in addition to the average fidelity value Rf, the calculation tool allows designers to see 1) the fidelity within color groups, called Hue Angle Bins, that encompass the entire color space 2) the direction of hue shift (if any) as displayed in the Color Vector Graphic, and 3) the Rf for each of the 99 Color Evaluation Samples (CES). Far from being a single value, as with Ra, TM-30 provides designers with layers of additional information about the performance of the lamp in question.<\/p>\n

In the next paragraph we are told \u201cThe IES-Rg metric can have a value greater than 100 and yet saturation might be lower than the reference light source for certain colors.\u201d Right again, but in a misleading way. As with color fidelity, TM-30\u2019s evaluation of color gamut is layered. Rg represents the average shift in saturation of the 99 CES. If a specifier wants deeper information it is available in the calculation tool as 1) a CES chromaticity comparison that plots the CES under both the reference illuminant and the test source so that one can see the shift 2) a graph showing the change of chroma by Hue Angle Bin.<\/p>\n

The entire third paragraph complains that if Rf is 100 there can be no increase or decrease in Rg – saturation is held at 100, too. This is like pointing out that the problem with taking a bath is that you get wet and soapy. The interrelation between Rf and Rg is a feature, not a bug. When the fidelity index of a light source matches it\u2019s reference then OF COURSE they will produce the same saturation of colors. If one wants to purposely increase or decrease saturation the only way to do so is to use a light source that is NOT an exact match to the reference source, and hence one that has a lower fidelity value. The relationship between Rf and Rg are shown as a graph in the calculation tool to help designers visualize the values that the tool calculates. That\u2019s a good thing.<\/p>\n

Finally, the paper concludes with \u201cIt is premature to consider IES TM-30-15 as a mandatory requirement or regulation because the metrics are likely to evolve.\u201d As I said at the beginning, this is a non-issue.<\/p>\n

The IES developed and issued TM-30 because CRI does not consistently and accurately represent the color rendering of many light sources, especially narrow band emitters like LEDs. This issue is well known and completely accepted by the industry, including the CIE. (A list of CRI\u2019s shortcomings is included in the latest edition of the IES Lighting Handbook<\/a>.) The IES position is that TM-30 \u201chas been developed for the benefit of the lighting community to provide: (a) a more accurate assessment of color fidelity; (b) an additional, complementary assessment of the influence of the preferred color appearance of objects (related to color gamut); and (c) more detailed information about the rendition of specific colors.\u201c and goes on to say that, \u201cthe issuance of TM-30-15 will enable the international lighting community to carefully evaluate it, providing a path leading to improved standards and design guidance. Technical analysis and feedback regarding the method described in TM-30 will be critical to continued development and standardization of color quality metrics.\u201d In other words, \u201cWe think this is a good tool. We\u2019re publishing it so that other concerned parties can evaluate it. We hope that this will trigger the acceptance of TM-30 or the development of another tool.\u201d<\/p>\n

Clearly NEMA as an organization, or members of their Lighting Systems Division, has a problem with the IES issuing TM-30, but the position paper is a red herring. It stirs up alarm over TM-30 becoming a requirement or regulation when the IES has noted\u00a0that isn\u2019t the purpose of a TM, and attempts to point out shortcomings that actually belong to CRI, not to TM-30. I don\u2019t know about the politics involved here, but I do know that this paper should be read with skepticism.<\/p>\n","protected":false},"excerpt":{"rendered":"

On November 12 the National Electrical Manufacturers Association (NEMA) published a position paper on IES TM-30-15. The document is here. It seems to be a willful misunderstanding and misrepresentation of TM-30. Here\u2019s how\u2026 The paper opens with NEMA\u2019s support of an improved color metric but then goes on to say that \u201cNEMA opposes any mandatory … Continue reading NEMA Misrepresents IES TM-30<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[12,18,17,19],"tags":[27,24],"class_list":["post-567","post","type-post","status-publish","format-standard","hentry","category-color","category-design","category-light","category-lighting-profession","tag-color-rendering","tag-led-color"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/p4gZSw-99","jetpack_sharing_enabled":true,"jetpack_likes_enabled":true,"jetpack-related-posts":[{"id":787,"url":"https:\/\/designinglight.com\/?p=787","url_meta":{"origin":567,"position":0},"title":"TM-30 Rf: So Big, So Strong, So Smart!","author":"Jason Livingston","date":"November 6, 2017","format":false,"excerpt":"As we know, CRI Ra and TM-30 Rf are both measurements of color fidelity. \u00a0That is, they compare a test light source to a known reference light source and measure how well the test source matches the reference source. \u00a0One of the many shortcomings of CRI Ra is that it\u2026","rel":"","context":"In "Color"","block_context":{"text":"Color","link":"https:\/\/designinglight.com\/?cat=12"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/designinglight.com\/wp-content\/uploads\/2017\/11\/CES-F32T8830.png?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/designinglight.com\/wp-content\/uploads\/2017\/11\/CES-F32T8830.png?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/designinglight.com\/wp-content\/uploads\/2017\/11\/CES-F32T8830.png?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/designinglight.com\/wp-content\/uploads\/2017\/11\/CES-F32T8830.png?resize=700%2C400&ssl=1 2x"},"classes":[]},{"id":1264,"url":"https:\/\/designinglight.com\/?p=1264","url_meta":{"origin":567,"position":1},"title":"Standard 189.1 Now Includes TM-30 Requirements","author":"Jason Livingston","date":"August 19, 2020","format":false,"excerpt":"Yesterday an addendum to ANSI\/ASHRAE\/ICC\/USGBC\/IES Standard 189.1-2017 Standard for the Design of High-Performance Green Buildings was published. The addendum makes changes to Section 8.3.5, which covers lighting. One of the biggest changes is to add TM-30 color rendition criteria to the section on Indoor Lighting Quality. Here's the relevant text:\u2026","rel":"","context":"In "Codes"","block_context":{"text":"Codes","link":"https:\/\/designinglight.com\/?cat=5"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":491,"url":"https:\/\/designinglight.com\/?p=491","url_meta":{"origin":567,"position":2},"title":"TM-30 and Color Gamut","author":"Jason Livingston","date":"August 26, 2015","format":false,"excerpt":"You may be familiar with the idea of a color gamut from displays or from RGB LED fixtures. In both cases the gamut describes the full range of colors that the device can create. In TM-30-15 IES Method for Evaluating Light Source Color Rendition gamut (Rg) has a somewhat different\u2026","rel":"","context":"In "Color"","block_context":{"text":"Color","link":"https:\/\/designinglight.com\/?cat=12"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":893,"url":"https:\/\/designinglight.com\/?p=893","url_meta":{"origin":567,"position":3},"title":"IES Updates Position on TM-30-18, IES Method for Evaluating Light Source Color Rendition","author":"Jason Livingston","date":"October 30, 2018","format":false,"excerpt":"The IES is about to release an update to TM-30 (TM-30--18). \u00a0Along with the updated version they have released this Position Statement. Source: PS-11-18: IES Position on TM-30-18, IES Method for Evaluating Light Source Color Rendition | IES","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":719,"url":"https:\/\/designinglight.com\/?p=719","url_meta":{"origin":567,"position":4},"title":"CIE Adopts TM-30 (sort of)","author":"Jason Livingston","date":"May 3, 2017","format":false,"excerpt":"The CIE has issued a statement titled \"CIE 2017 Colour Fidelity Index for accurate scientific use\" in which they partially adopt the Rf fidelity metric of TM-30. \u00a0Here are some of the details. When the IES released TM-30-15 it seemed to be a wake up call for the CIE, who\u2026","rel":"","context":"In "Color"","block_context":{"text":"Color","link":"https:\/\/designinglight.com\/?cat=12"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":4039,"url":"https:\/\/designinglight.com\/?p=4039","url_meta":{"origin":567,"position":5},"title":"How are CCT and Duv Calculated? IES TM-40","author":"Jason Livingston","date":"September 30, 2024","format":false,"excerpt":"If you look up the definition of Correlated Color Temperature (CCT) in IES LS-1 you'll find, \"The absolute temperature of a blackbody whose chromaticity most nearly resembles that of the light source.\" \u00a0It seems straightforward. \u00a0The spectra of non-incandescent light sources don't exactly match a blackbody radiator. \u00a0They'll plot off\u2026","rel":"","context":"In "Color"","block_context":{"text":"Color","link":"https:\/\/designinglight.com\/?cat=12"},"img":{"alt_text":"C78.377 chromaticity quadrangles","src":"https:\/\/i0.wp.com\/designinglight.com\/wp-content\/uploads\/2024\/09\/3.8-C78.377-300x300.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]}],"_links":{"self":[{"href":"https:\/\/designinglight.com\/index.php?rest_route=\/wp\/v2\/posts\/567","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/designinglight.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/designinglight.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/designinglight.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/designinglight.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=567"}],"version-history":[{"count":2,"href":"https:\/\/designinglight.com\/index.php?rest_route=\/wp\/v2\/posts\/567\/revisions"}],"predecessor-version":[{"id":570,"href":"https:\/\/designinglight.com\/index.php?rest_route=\/wp\/v2\/posts\/567\/revisions\/570"}],"wp:attachment":[{"href":"https:\/\/designinglight.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=567"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/designinglight.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=567"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/designinglight.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=567"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}