{"id":194,"date":"2026-04-01T15:01:17","date_gmt":"2026-04-01T06:01:17","guid":{"rendered":"https:\/\/www.san-eielectric.co.jp\/am\/?page_id=194"},"modified":"2026-04-28T12:12:57","modified_gmt":"2026-04-28T03:12:57","slug":"spectral-match-bins-why-band-definition-matters","status":"publish","type":"page","link":"https:\/\/www.san-eielectric.co.jp\/am\/en\/technical-note\/spectral-match-bins-why-band-definition-matters\/","title":{"rendered":"Spectral Match Bins: Why Band Definition Matters"},"content":{"rendered":"\n<ul class=\"wp-block-list\">\n<li class=\"has-medium-font-size\">Technical Note \/ Spectral Match and Bins<\/li>\n\n\n\n<li class=\"has-medium-font-size\">Title: Spectral Match Bins: Why Band Definition Matters<\/li>\n\n\n\n<li class=\"has-medium-font-size\">1-line summary: Practical guidance on band (bin) selection and interpretation for AM1.5G\/AM0 evaluations.<\/li>\n\n\n\n<li class=\"has-medium-font-size\">Date: 2026-02-21<\/li>\n\n\n\n<li class=\"has-medium-font-size\">Spectrum: Both<\/li>\n\n\n\n<li class=\"has-medium-font-size\">Level: Standard (or Advanced)<\/li>\n\n\n\n<li class=\"has-medium-font-size\">Category: Spectral Match and Bins<\/li>\n\n\n\n<li class=\"has-medium-font-size\">Related: Spectral Match vs Spectral Fidelity \/ Spectral Match Verification (AM1.5G \/ AM0)<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading has-base-color has-contrast-background-color has-text-color has-background has-link-color has-large-font-size wp-elements-4540ef43c93b5f0a00661a71ae0e51b7\" style=\"padding-top:var(--wp--preset--spacing--20);padding-right:var(--wp--preset--spacing--20);padding-bottom:var(--wp--preset--spacing--20);padding-left:var(--wp--preset--spacing--20)\">1. Purpose<\/h2>\n\n\n\n<p class=\"has-medium-font-size wp-block-paragraph\">\u201cSpectral match class\u201d looks like a single label, but the result depends heavily on <strong>how bins are defined<\/strong>.<br>This note explains:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"has-medium-font-size\">why bin edges matter,<\/li>\n\n\n\n<li class=\"has-medium-font-size\">why \u201csame class\u201d does not always mean \u201csame spectrum quality,\u201d<\/li>\n\n\n\n<li class=\"has-medium-font-size\">what you must state so the class label is not misleading.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading has-base-color has-contrast-background-color has-text-color has-background has-link-color has-large-font-size wp-elements-670cbe065435ab735bbd768849cf8133\" style=\"padding-top:var(--wp--preset--spacing--20);padding-right:var(--wp--preset--spacing--20);padding-bottom:var(--wp--preset--spacing--20);padding-left:var(--wp--preset--spacing--20)\">2. Definitions (quick)<\/h2>\n\n\n\n<h3 class=\"wp-block-heading has-contrast-color has-text-color has-link-color has-large-font-size wp-elements-9ca9476b3fe4a2641a573342e65fa567\" style=\"border-width:1px;padding-top:5px;padding-right:var(--wp--preset--spacing--20);padding-bottom:5px;padding-left:var(--wp--preset--spacing--20)\">2.1 Bin (band)<\/h3>\n\n\n\n<p class=\"has-medium-font-size wp-block-paragraph\">A predefined wavelength interval used to integrate irradiance and compare ratios to a reference spectrum.<\/p>\n\n\n\n<h3 class=\"wp-block-heading has-contrast-color has-text-color has-link-color has-large-font-size wp-elements-9813f149d4427aed616edc488818689b\" style=\"border-width:1px;padding-top:5px;padding-right:var(--wp--preset--spacing--20);padding-bottom:5px;padding-left:var(--wp--preset--spacing--20)\">2.2 Bin set<\/h3>\n\n\n\n<p class=\"has-medium-font-size wp-block-paragraph\">A full list of bin edges that covers the evaluation wavelength range (e.g., 6-bin, 9-bin, 10-bin)<\/p>\n\n\n\n<h3 class=\"wp-block-heading has-contrast-color has-text-color has-link-color has-large-font-size wp-elements-b928453b80c8d0c9a996c98b9b0ac846\" style=\"border-width:1px;padding-top:5px;padding-right:var(--wp--preset--spacing--20);padding-bottom:5px;padding-left:var(--wp--preset--spacing--20)\">2.3 Why spectral match is bin-dependent<\/h3>\n\n\n\n<p class=\"has-medium-font-size wp-block-paragraph\">Spectral match is computed from <strong>band-integrated ratios<\/strong>, so changing bin edges changes:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"has-medium-font-size\">which spectral features are averaged together,<\/li>\n\n\n\n<li class=\"has-medium-font-size\">how strongly local deviations influence the ratio,<\/li>\n\n\n\n<li class=\"has-medium-font-size\">how \u201cforgiving\u201d or \u201csensitive\u201d the classification becomes.<\/li>\n<\/ul>\n\n\n\n<p class=\"has-medium-font-size wp-block-paragraph\">Key point: You must specify <strong>(a) wavelength range<\/strong>, <strong>(b) bin set<\/strong>, <strong>(c) reference spectrum definition<\/strong>, <strong>(d) measurement basis<\/strong>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading has-base-color has-contrast-background-color has-text-color has-background has-link-color has-large-font-size wp-elements-7d0ab3a187c0c0f2c7c7129f711d0115\" style=\"padding-top:var(--wp--preset--spacing--20);padding-right:var(--wp--preset--spacing--20);padding-bottom:var(--wp--preset--spacing--20);padding-left:var(--wp--preset--spacing--20)\">3. Common misunderstanding (and the fix)<\/h2>\n\n\n\n<h3 class=\"wp-block-heading has-contrast-color has-text-color has-link-color has-large-font-size wp-elements-556f179da672cb5bdef9a6b50f935e17\" style=\"border-width:1px;padding-top:5px;padding-right:var(--wp--preset--spacing--20);padding-bottom:5px;padding-left:var(--wp--preset--spacing--20)\">3.1 Typical misunderstandings<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"has-medium-font-size\">\u201cClass A is Class A\u201d (without stating range\/bins).<\/li>\n\n\n\n<li class=\"has-medium-font-size\">Assuming that a better class automatically means better agreement at every wavelength.<\/li>\n\n\n\n<li class=\"has-medium-font-size\">Comparing results between AM1.5G and AM0 using the same wording, while the relevant spectral emphasis differs.<\/li>\n\n\n\n<li class=\"has-medium-font-size\">Using a custom bin set but reporting it as if it were a standard bin set.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading has-contrast-color has-text-color has-link-color has-large-font-size wp-elements-46101b087032adcf44d5ea8a3ce54a96\" style=\"border-width:1px;padding-top:5px;padding-right:var(--wp--preset--spacing--20);padding-bottom:5px;padding-left:var(--wp--preset--spacing--20)\">3.2 Fix: simple reporting rule (always state these 4 items)<\/h3>\n\n\n\n<p class=\"has-medium-font-size wp-block-paragraph\">Whenever you write \u201cspectral match,\u201d state:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"has-medium-font-size\"><strong>Wavelength range:<\/strong> ______ (e.g., <strong><em>\u2013<\/em><\/strong> nm)<\/li>\n\n\n\n<li class=\"has-medium-font-size\"><strong>Bin set (edges):<\/strong> ______ (e.g., \u201cIEC-style 6-bin\u201d \/ \u201cextended 10-bin\u201d \/ custom list)<\/li>\n\n\n\n<li class=\"has-medium-font-size\"><strong>Reference spectrum:<\/strong> ______ (AM1.5G \/ AM0 and version)<\/li>\n\n\n\n<li class=\"has-medium-font-size\"><strong>Measurement basis:<\/strong> instrument \/ resolution \/ method \/ traceability: ______<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading has-base-color has-contrast-background-color has-text-color has-background has-link-color has-large-font-size wp-elements-bbfdf18e3cbce80b50757e1de3f4a0f7\" style=\"padding-top:var(--wp--preset--spacing--20);padding-right:var(--wp--preset--spacing--20);padding-bottom:var(--wp--preset--spacing--20);padding-left:var(--wp--preset--spacing--20)\">4. What to say (recommended wording examples)<\/h2>\n\n\n\n<p class=\"has-medium-font-size wp-block-paragraph\">A) Standard-style reporting<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"has-medium-font-size\">\u201cSpectral match classification was evaluated over <strong><em>\u2013<\/em><\/strong> nm using the ___-bin set (bin edges: ___) against the ___ reference spectrum. Measurement was performed with ___ (resolution ___ nm), traceable to ___.\u201d<\/li>\n<\/ul>\n\n\n\n<p class=\"has-medium-font-size wp-block-paragraph\">B) If you used a custom bin set (recommended transparency)<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"has-medium-font-size\">\u201cA custom bin set was used to better reflect ___; therefore the class result is not directly comparable to results based on ___-bin definitions.\u201d<\/li>\n<\/ul>\n\n\n\n<p class=\"has-medium-font-size wp-block-paragraph\">C) Best practice (avoid confusion)<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"has-medium-font-size\">\u201cWe report spectral match (bins\/classification) together with a high-resolution spectrum\/residual plot when interpretation confidence is needed.\u201d<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading has-base-color has-contrast-background-color has-text-color has-background has-link-color has-large-font-size wp-elements-f38871ac57eba273ffb7c62778571740\" style=\"padding-top:var(--wp--preset--spacing--20);padding-right:var(--wp--preset--spacing--20);padding-bottom:var(--wp--preset--spacing--20);padding-left:var(--wp--preset--spacing--20)\">5. Quick comparison table<\/h2>\n\n\n\n<figure class=\"wp-block-table has-medium-font-size\"><table class=\"has-fixed-layout\"><tbody><tr><td><strong>Item<\/strong><\/td><td><strong>Coarser bin set<\/strong><\/td><td><strong>Finer \/ extended bin set<\/strong><\/td><\/tr><tr><td>Sensitivity to narrow spectral features<\/td><td>Lower (features averaged out)<\/td><td>Higher (features affect ratios)<\/td><\/tr><tr><td>Risk<\/td><td>Can hide local deviations<\/td><td>Can over-emphasize small local deviations if noise is high<\/td><\/tr><tr><td>Best for<\/td><td>Simple classification \/ routine checks<\/td><td>Grid stated; symmetric around center<\/td><\/tr><tr><td>Control scan time vs drift<\/td><td>Spatial map should not become time trend<\/td><td>Engineering, filter design, deeper interpretation<\/td><\/tr><tr><td>Comparability across sites<\/td><td>Higher if widely standardized<\/td><td>Requires clearer documentation of bin edges<\/td><\/tr><tr><td>Typical use case<\/td><td>Pass\/fail style reporting<\/td><td>\u201cWhy does it differ?\u201d analysis<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h2 class=\"wp-block-heading has-base-color has-contrast-background-color has-text-color has-background has-link-color has-large-font-size wp-elements-5be270a1627320e6c924c1e7455eff35\" style=\"padding-top:var(--wp--preset--spacing--20);padding-right:var(--wp--preset--spacing--20);padding-bottom:var(--wp--preset--spacing--20);padding-left:var(--wp--preset--spacing--20)\">6. Notes (SAN-EI recommendation)<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"has-medium-font-size\">If your goal is <strong>classification<\/strong>, use <strong>a clearly defined standard-style bin set<\/strong> and report it explicitly.<\/li>\n\n\n\n<li class=\"has-medium-font-size\">If your goal is <strong>engineering improvement<\/strong> (AM filter design, lamp tuning), use an extended or finer bin set <em>plus<\/em> a high-resolution residual plot.<\/li>\n\n\n\n<li class=\"has-medium-font-size\">Do not let a single label replace documentation. A correct one-line summary format is:<\/li>\n<\/ul>\n\n\n\n<p class=\"has-medium-font-size wp-block-paragraph\">\u201cSpectral match: Class ___ under <strong><em>\u2013<\/em><\/strong> nm using ___-bin set (edges stated).\u201d<\/p>\n\n\n\n<p class=\"has-medium-font-size wp-block-paragraph\"><a href=\"https:\/\/www.san-eielectric.co.jp\/am\/en\/technical-note\/\" data-type=\"page\" data-id=\"181\"><\/a><a href=\"https:\/\/www.san-eielectric.co.jp\/am\/en\/technical-note\/\" data-type=\"page\" data-id=\"181\">Return to INDEX<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>1. Purpose \u201cSpectral match class\u201d looks like a single label, but the result depends heavily on how bins are de [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":181,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-194","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.san-eielectric.co.jp\/am\/wp-json\/wp\/v2\/pages\/194","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.san-eielectric.co.jp\/am\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.san-eielectric.co.jp\/am\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.san-eielectric.co.jp\/am\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.san-eielectric.co.jp\/am\/wp-json\/wp\/v2\/comments?post=194"}],"version-history":[{"count":6,"href":"https:\/\/www.san-eielectric.co.jp\/am\/wp-json\/wp\/v2\/pages\/194\/revisions"}],"predecessor-version":[{"id":1040,"href":"https:\/\/www.san-eielectric.co.jp\/am\/wp-json\/wp\/v2\/pages\/194\/revisions\/1040"}],"up":[{"embeddable":true,"href":"https:\/\/www.san-eielectric.co.jp\/am\/wp-json\/wp\/v2\/pages\/181"}],"wp:attachment":[{"href":"https:\/\/www.san-eielectric.co.jp\/am\/wp-json\/wp\/v2\/media?parent=194"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}