{"id":"https://openalex.org/W2085145797","doi":"https://doi.org/10.3390/s131216682","title":"Hierarchical Recognition Scheme for Human Facial Expression Recognition Systems","display_name":"Hierarchical Recognition Scheme for Human Facial Expression Recognition Systems","publication_year":2013,"publication_date":"2013-12-05","ids":{"openalex":"https://openalex.org/W2085145797","doi":"https://doi.org/10.3390/s131216682","mag":"2085145797","pmid":"https://pubmed.ncbi.nlm.nih.gov/24316568"},"language":"en","primary_location":{"id":"doi:10.3390/s131216682","is_oa":true,"landing_page_url":"https://doi.org/10.3390/s131216682","pdf_url":"https://www.mdpi.com/1424-8220/13/12/16682/pdf?version=1403340052","source":{"id":"https://openalex.org/S101949793","display_name":"Sensors","issn_l":"1424-8220","issn":["1424-8220"],"is_oa":true,"is_in_doaj":true,"is_core":true,"host_organization":"https://openalex.org/P4310310987","host_organization_name":"Multidisciplinary Digital Publishing Institute","host_organization_lineage":["https://openalex.org/P4310310987"],"host_organization_lineage_names":["Multidisciplinary Digital Publishing Institute"],"type":"journal"},"license":"cc-by","license_id":"https://openalex.org/licenses/cc-by","version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"Sensors","raw_type":"journal-article"},"type":"article","indexed_in":["crossref","doaj","pubmed"],"open_access":{"is_oa":true,"oa_status":"gold","oa_url":"https://www.mdpi.com/1424-8220/13/12/16682/pdf?version=1403340052","any_repository_has_fulltext":true},"authorships":[{"author_position":"first","author":{"id":"https://openalex.org/A5112075425","display_name":"Muhammad Siddiqi","orcid":null},"institutions":[{"id":"https://openalex.org/I35928602","display_name":"Kyung Hee University","ror":"https://ror.org/01zqcg218","country_code":"KR","type":"education","lineage":["https://openalex.org/I35928602"]}],"countries":["KR"],"is_corresponding":false,"raw_author_name":"Muhammad Siddiqi","raw_affiliation_strings":["UC Lab, Department of Computer Engineering, Kyung Hee University, Yongin-Si 446-701, Korea"],"affiliations":[{"raw_affiliation_string":"UC Lab, Department of Computer Engineering, Kyung Hee University, Yongin-Si 446-701, Korea","institution_ids":["https://openalex.org/I35928602"]}]},{"author_position":"middle","author":{"id":"https://openalex.org/A5101882040","display_name":"Sungyoung Lee","orcid":"https://orcid.org/0000-0002-5962-1587"},"institutions":[{"id":"https://openalex.org/I35928602","display_name":"Kyung Hee University","ror":"https://ror.org/01zqcg218","country_code":"KR","type":"education","lineage":["https://openalex.org/I35928602"]}],"countries":["KR"],"is_corresponding":false,"raw_author_name":"Sungyoung Lee","raw_affiliation_strings":["UC Lab, Department of Computer Engineering, Kyung Hee University, Yongin-Si 446-701, Korea"],"affiliations":[{"raw_affiliation_string":"UC Lab, Department of Computer Engineering, Kyung Hee University, Yongin-Si 446-701, Korea","institution_ids":["https://openalex.org/I35928602"]}]},{"author_position":"middle","author":{"id":"https://openalex.org/A5039165136","display_name":"Young-Koo Lee","orcid":"https://orcid.org/0000-0003-2314-5395"},"institutions":[{"id":"https://openalex.org/I35928602","display_name":"Kyung Hee University","ror":"https://ror.org/01zqcg218","country_code":"KR","type":"education","lineage":["https://openalex.org/I35928602"]}],"countries":["KR"],"is_corresponding":false,"raw_author_name":"Young-Koo Lee","raw_affiliation_strings":["UC Lab, Department of Computer Engineering, Kyung Hee University, Yongin-Si 446-701, Korea"],"affiliations":[{"raw_affiliation_string":"UC Lab, Department of Computer Engineering, Kyung Hee University, Yongin-Si 446-701, Korea","institution_ids":["https://openalex.org/I35928602"]}]},{"author_position":"middle","author":{"id":"https://openalex.org/A5070522496","display_name":"Adil Khan","orcid":"https://orcid.org/0000-0003-2220-8518"},"institutions":[{"id":"https://openalex.org/I57664883","display_name":"Ajou University","ror":"https://ror.org/03tzb2h73","country_code":"KR","type":"education","lineage":["https://openalex.org/I57664883"]}],"countries":["KR"],"is_corresponding":false,"raw_author_name":"Adil Khan","raw_affiliation_strings":["Division of Information and Computer Engineering, Ajou University, Suwon 443-749, Korea"],"affiliations":[{"raw_affiliation_string":"Division of Information and Computer Engineering, Ajou University, Suwon 443-749, Korea","institution_ids":["https://openalex.org/I57664883"]}]},{"author_position":"last","author":{"id":"https://openalex.org/A5071628406","display_name":"Phan Tran Ho Truc","orcid":null},"institutions":[{"id":"https://openalex.org/I35928602","display_name":"Kyung Hee University","ror":"https://ror.org/01zqcg218","country_code":"KR","type":"education","lineage":["https://openalex.org/I35928602"]}],"countries":["KR"],"is_corresponding":true,"raw_author_name":"Phan Truc","raw_affiliation_strings":["UC Lab, Department of Computer Engineering, Kyung Hee University, Yongin-Si 446-701, Korea"],"affiliations":[{"raw_affiliation_string":"UC Lab, Department of Computer Engineering, Kyung Hee University, Yongin-Si 446-701, Korea","institution_ids":["https://openalex.org/I35928602"]}]}],"institutions":[],"countries_distinct_count":1,"institutions_distinct_count":5,"corresponding_author_ids":["https://openalex.org/A5071628406"],"corresponding_institution_ids":["https://openalex.org/I35928602"],"apc_list":{"value":2400,"currency":"CHF","value_usd":2598},"apc_paid":{"value":2400,"currency":"CHF","value_usd":2598},"fwci":3.5892,"has_fulltext":false,"cited_by_count":38,"citation_normalized_percentile":{"value":0.93956378,"is_in_top_1_percent":false,"is_in_top_10_percent":true},"cited_by_percentile_year":{"min":90,"max":98},"biblio":{"volume":"13","issue":"12","first_page":"16682","last_page":"16713"},"is_retracted":false,"is_paratext":false,"is_xpac":false,"primary_topic":{"id":"https://openalex.org/T10057","display_name":"Face and Expression Recognition","score":0.9994999766349792,"subfield":{"id":"https://openalex.org/subfields/1707","display_name":"Computer Vision and Pattern Recognition"},"field":{"id":"https://openalex.org/fields/17","display_name":"Computer Science"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},"topics":[{"id":"https://openalex.org/T10057","display_name":"Face and Expression Recognition","score":0.9994999766349792,"subfield":{"id":"https://openalex.org/subfields/1707","display_name":"Computer Vision and Pattern Recognition"},"field":{"id":"https://openalex.org/fields/17","display_name":"Computer Science"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},{"id":"https://openalex.org/T10667","display_name":"Emotion and Mood Recognition","score":0.9983999729156494,"subfield":{"id":"https://openalex.org/subfields/3205","display_name":"Experimental and Cognitive Psychology"},"field":{"id":"https://openalex.org/fields/32","display_name":"Psychology"},"domain":{"id":"https://openalex.org/domains/2","display_name":"Social Sciences"}},{"id":"https://openalex.org/T13731","display_name":"Advanced Computing and Algorithms","score":0.9714999794960022,"subfield":{"id":"https://openalex.org/subfields/3322","display_name":"Urban Studies"},"field":{"id":"https://openalex.org/fields/33","display_name":"Social Sciences"},"domain":{"id":"https://openalex.org/domains/2","display_name":"Social Sciences"}}],"keywords":[{"id":"https://openalex.org/keywords/pattern-recognition","display_name":"Pattern recognition (psychology)","score":0.7275639176368713},{"id":"https://openalex.org/keywords/artificial-intelligence","display_name":"Artificial intelligence","score":0.6787075996398926},{"id":"https://openalex.org/keywords/similarity","display_name":"Similarity (geometry)","score":0.6161933541297913},{"id":"https://openalex.org/keywords/computer-science","display_name":"Computer science","score":0.5867927074432373},{"id":"https://openalex.org/keywords/face","display_name":"Face (sociological concept)","score":0.5538628101348877},{"id":"https://openalex.org/keywords/linear-discriminant-analysis","display_name":"Linear discriminant analysis","score":0.5320008397102356},{"id":"https://openalex.org/keywords/facial-recognition-system","display_name":"Facial recognition system","score":0.48766815662384033},{"id":"https://openalex.org/keywords/facial-expression","display_name":"Facial expression","score":0.4839175343513489},{"id":"https://openalex.org/keywords/discriminant","display_name":"Discriminant","score":0.47766146063804626},{"id":"https://openalex.org/keywords/cross-validation","display_name":"Cross-validation","score":0.47748610377311707},{"id":"https://openalex.org/keywords/feature-extraction","display_name":"Feature extraction","score":0.47614359855651855},{"id":"https://openalex.org/keywords/scheme","display_name":"Scheme (mathematics)","score":0.4688386023044586},{"id":"https://openalex.org/keywords/set","display_name":"Set (abstract data type)","score":0.4430922865867615},{"id":"https://openalex.org/keywords/mathematics","display_name":"Mathematics","score":0.23417499661445618},{"id":"https://openalex.org/keywords/image","display_name":"Image (mathematics)","score":0.14487844705581665}],"concepts":[{"id":"https://openalex.org/C153180895","wikidata":"https://www.wikidata.org/wiki/Q7148389","display_name":"Pattern recognition (psychology)","level":2,"score":0.7275639176368713},{"id":"https://openalex.org/C154945302","wikidata":"https://www.wikidata.org/wiki/Q11660","display_name":"Artificial intelligence","level":1,"score":0.6787075996398926},{"id":"https://openalex.org/C103278499","wikidata":"https://www.wikidata.org/wiki/Q254465","display_name":"Similarity (geometry)","level":3,"score":0.6161933541297913},{"id":"https://openalex.org/C41008148","wikidata":"https://www.wikidata.org/wiki/Q21198","display_name":"Computer science","level":0,"score":0.5867927074432373},{"id":"https://openalex.org/C2779304628","wikidata":"https://www.wikidata.org/wiki/Q3503480","display_name":"Face (sociological concept)","level":2,"score":0.5538628101348877},{"id":"https://openalex.org/C69738355","wikidata":"https://www.wikidata.org/wiki/Q1228929","display_name":"Linear discriminant analysis","level":2,"score":0.5320008397102356},{"id":"https://openalex.org/C31510193","wikidata":"https://www.wikidata.org/wiki/Q1192553","display_name":"Facial recognition system","level":3,"score":0.48766815662384033},{"id":"https://openalex.org/C195704467","wikidata":"https://www.wikidata.org/wiki/Q327968","display_name":"Facial expression","level":2,"score":0.4839175343513489},{"id":"https://openalex.org/C78397625","wikidata":"https://www.wikidata.org/wiki/Q192487","display_name":"Discriminant","level":2,"score":0.47766146063804626},{"id":"https://openalex.org/C27181475","wikidata":"https://www.wikidata.org/wiki/Q541014","display_name":"Cross-validation","level":2,"score":0.47748610377311707},{"id":"https://openalex.org/C52622490","wikidata":"https://www.wikidata.org/wiki/Q1026626","display_name":"Feature extraction","level":2,"score":0.47614359855651855},{"id":"https://openalex.org/C77618280","wikidata":"https://www.wikidata.org/wiki/Q1155772","display_name":"Scheme (mathematics)","level":2,"score":0.4688386023044586},{"id":"https://openalex.org/C177264268","wikidata":"https://www.wikidata.org/wiki/Q1514741","display_name":"Set (abstract data type)","level":2,"score":0.4430922865867615},{"id":"https://openalex.org/C33923547","wikidata":"https://www.wikidata.org/wiki/Q395","display_name":"Mathematics","level":0,"score":0.23417499661445618},{"id":"https://openalex.org/C115961682","wikidata":"https://www.wikidata.org/wiki/Q860623","display_name":"Image (mathematics)","level":2,"score":0.14487844705581665},{"id":"https://openalex.org/C36289849","wikidata":"https://www.wikidata.org/wiki/Q34749","display_name":"Social science","level":1,"score":0.0},{"id":"https://openalex.org/C144024400","wikidata":"https://www.wikidata.org/wiki/Q21201","display_name":"Sociology","level":0,"score":0.0},{"id":"https://openalex.org/C199360897","wikidata":"https://www.wikidata.org/wiki/Q9143","display_name":"Programming language","level":1,"score":0.0},{"id":"https://openalex.org/C134306372","wikidata":"https://www.wikidata.org/wiki/Q7754","display_name":"Mathematical analysis","level":1,"score":0.0}],"mesh":[{"descriptor_ui":"D005145","descriptor_name":"Face","qualifier_ui":"Q000502","qualifier_name":"physiology","is_major_topic":false},{"descriptor_ui":"D005145","descriptor_name":"Face","qualifier_ui":"Q000502","qualifier_name":"physiology","is_major_topic":false},{"descriptor_ui":"D005145","descriptor_name":"Face","qualifier_ui":"Q000502","qualifier_name":"physiology","is_major_topic":false},{"descriptor_ui":"D005149","descriptor_name":"Facial Expression","qualifier_ui":null,"qualifier_name":null,"is_major_topic":true},{"descriptor_ui":"D005149","descriptor_name":"Facial Expression","qualifier_ui":null,"qualifier_name":null,"is_major_topic":true},{"descriptor_ui":"D005149","descriptor_name":"Facial Expression","qualifier_ui":null,"qualifier_name":null,"is_major_topic":true},{"descriptor_ui":"D006801","descriptor_name":"Humans","qualifier_ui":null,"qualifier_name":null,"is_major_topic":false},{"descriptor_ui":"D006801","descriptor_name":"Humans","qualifier_ui":null,"qualifier_name":null,"is_major_topic":false},{"descriptor_ui":"D006801","descriptor_name":"Humans","qualifier_ui":null,"qualifier_name":null,"is_major_topic":false},{"descriptor_ui":"D016002","descriptor_name":"Discriminant Analysis","qualifier_ui":null,"qualifier_name":null,"is_major_topic":false},{"descriptor_ui":"D016002","descriptor_name":"Discriminant Analysis","qualifier_ui":null,"qualifier_name":null,"is_major_topic":false},{"descriptor_ui":"D016002","descriptor_name":"Discriminant Analysis","qualifier_ui":null,"qualifier_name":null,"is_major_topic":false},{"descriptor_ui":"D046709","descriptor_name":"Pattern Recognition, Physiological","qualifier_ui":"Q000502","qualifier_name":"physiology","is_major_topic":false},{"descriptor_ui":"D046709","descriptor_name":"Pattern Recognition, Physiological","qualifier_ui":"Q000502","qualifier_name":"physiology","is_major_topic":false},{"descriptor_ui":"D046709","descriptor_name":"Pattern Recognition, Physiological","qualifier_ui":"Q000502","qualifier_name":"physiology","is_major_topic":false}],"locations_count":5,"locations":[{"id":"doi:10.3390/s131216682","is_oa":true,"landing_page_url":"https://doi.org/10.3390/s131216682","pdf_url":"https://www.mdpi.com/1424-8220/13/12/16682/pdf?version=1403340052","source":{"id":"https://openalex.org/S101949793","display_name":"Sensors","issn_l":"1424-8220","issn":["1424-8220"],"is_oa":true,"is_in_doaj":true,"is_core":true,"host_organization":"https://openalex.org/P4310310987","host_organization_name":"Multidisciplinary Digital Publishing Institute","host_organization_lineage":["https://openalex.org/P4310310987"],"host_organization_lineage_names":["Multidisciplinary Digital Publishing Institute"],"type":"journal"},"license":"cc-by","license_id":"https://openalex.org/licenses/cc-by","version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"Sensors","raw_type":"journal-article"},{"id":"pmid:24316568","is_oa":false,"landing_page_url":"https://pubmed.ncbi.nlm.nih.gov/24316568","pdf_url":null,"source":{"id":"https://openalex.org/S4306525036","display_name":"PubMed","issn_l":null,"issn":null,"is_oa":false,"is_in_doaj":false,"is_core":false,"host_organization":"https://openalex.org/I1299303238","host_organization_name":"National Institutes of Health","host_organization_lineage":["https://openalex.org/I1299303238"],"host_organization_lineage_names":[],"type":"repository"},"license":null,"license_id":null,"version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"Sensors (Basel, Switzerland)","raw_type":null},{"id":"pmh:oai:doaj.org/article:4ac7f594265c403b95c6ca2ac1242b82","is_oa":true,"landing_page_url":"https://doaj.org/article/4ac7f594265c403b95c6ca2ac1242b82","pdf_url":null,"source":{"id":"https://openalex.org/S112646816","display_name":"SHILAP Revista de lepidopterolog\u00eda","issn_l":"0300-5267","issn":["0300-5267","2340-4078"],"is_oa":true,"is_in_doaj":true,"is_core":false,"host_organization":null,"host_organization_name":null,"host_organization_lineage":[],"host_organization_lineage_names":[],"type":"journal"},"license":"cc-by-sa","license_id":"https://openalex.org/licenses/cc-by-sa","version":"submittedVersion","is_accepted":false,"is_published":false,"raw_source_name":"Sensors, Vol 13, Iss 12, Pp 16682-16713 (2013)","raw_type":"article"},{"id":"pmh:oai:europepmc.org:2881275","is_oa":true,"landing_page_url":"https://www.ncbi.nlm.nih.gov/pmc/articles/3892857","pdf_url":null,"source":{"id":"https://openalex.org/S4306400806","display_name":"Europe PMC (PubMed Central)","issn_l":null,"issn":null,"is_oa":false,"is_in_doaj":false,"is_core":false,"host_organization":"https://openalex.org/I1303153112","host_organization_name":"European Bioinformatics Institute","host_organization_lineage":["https://openalex.org/I1303153112"],"host_organization_lineage_names":[],"type":"repository"},"license":"cc-by","license_id":"https://openalex.org/licenses/cc-by","version":"submittedVersion","is_accepted":false,"is_published":false,"raw_source_name":null,"raw_type":"Text"},{"id":"pmh:oai:mdpi.com:/1424-8220/13/12/16682/","is_oa":true,"landing_page_url":"https://dx.doi.org/10.3390/s131216682","pdf_url":null,"source":{"id":"https://openalex.org/S4306400947","display_name":"MDPI (MDPI AG)","issn_l":null,"issn":null,"is_oa":true,"is_in_doaj":false,"is_core":false,"host_organization":"https://openalex.org/I4210097602","host_organization_name":"Multidisciplinary Digital Publishing Institute (Switzerland)","host_organization_lineage":["https://openalex.org/I4210097602"],"host_organization_lineage_names":[],"type":"repository"},"license":"cc-by","license_id":"https://openalex.org/licenses/cc-by","version":"submittedVersion","is_accepted":false,"is_published":false,"raw_source_name":"Sensors; Volume 13; Issue 12; Pages: 16682-16713","raw_type":"Text"}],"best_oa_location":{"id":"doi:10.3390/s131216682","is_oa":true,"landing_page_url":"https://doi.org/10.3390/s131216682","pdf_url":"https://www.mdpi.com/1424-8220/13/12/16682/pdf?version=1403340052","source":{"id":"https://openalex.org/S101949793","display_name":"Sensors","issn_l":"1424-8220","issn":["1424-8220"],"is_oa":true,"is_in_doaj":true,"is_core":true,"host_organization":"https://openalex.org/P4310310987","host_organization_name":"Multidisciplinary Digital Publishing Institute","host_organization_lineage":["https://openalex.org/P4310310987"],"host_organization_lineage_names":["Multidisciplinary Digital Publishing Institute"],"type":"journal"},"license":"cc-by","license_id":"https://openalex.org/licenses/cc-by","version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"Sensors","raw_type":"journal-article"},"sustainable_development_goals":[{"score":0.6899999976158142,"display_name":"Reduced inequalities","id":"https://metadata.un.org/sdg/10"}],"awards":[],"funders":[],"has_content":{"pdf":true,"grobid_xml":true},"content_urls":{"pdf":"https://content.openalex.org/works/W2085145797.pdf","grobid_xml":"https://content.openalex.org/works/W2085145797.grobid-xml"},"referenced_works_count":94,"referenced_works":["https://openalex.org/W1483662103","https://openalex.org/W1514545595","https://openalex.org/W1575540224","https://openalex.org/W1583737874","https://openalex.org/W1602756618","https://openalex.org/W1640878532","https://openalex.org/W1964762821","https://openalex.org/W1981681962","https://openalex.org/W1992683700","https://openalex.org/W2006431213","https://openalex.org/W2007431552","https://openalex.org/W2008056655","https://openalex.org/W2008999667","https://openalex.org/W2014835756","https://openalex.org/W2020187819","https://openalex.org/W2022214793","https://openalex.org/W2033773055","https://openalex.org/W2038219329","https://openalex.org/W2043299520","https://openalex.org/W2044399959","https://openalex.org/W2044798275","https://openalex.org/W2048048394","https://openalex.org/W2052024152","https://openalex.org/W2053432263","https://openalex.org/W2058561032","https://openalex.org/W2066949013","https://openalex.org/W2067893425","https://openalex.org/W2071352213","https://openalex.org/W2071931902","https://openalex.org/W2074867602","https://openalex.org/W2074885606","https://openalex.org/W2090425484","https://openalex.org/W2091550557","https://openalex.org/W2096044434","https://openalex.org/W2097844709","https://openalex.org/W2098044144","https://openalex.org/W2100418198","https://openalex.org/W2101176070","https://openalex.org/W2102570318","https://openalex.org/W2103560185","https://openalex.org/W2104773058","https://openalex.org/W2106115875","https://openalex.org/W2107488200","https://openalex.org/W2111123712","https://openalex.org/W2121394390","https://openalex.org/W2123736354","https://openalex.org/W2123921160","https://openalex.org/W2124901121","https://openalex.org/W2125127226","https://openalex.org/W2127196145","https://openalex.org/W2127483610","https://openalex.org/W2129442134","https://openalex.org/W2130877515","https://openalex.org/W2133045835","https://openalex.org/W2133047203","https://openalex.org/W2133775535","https://openalex.org/W2137338002","https://openalex.org/W2138261336","https://openalex.org/W2141567247","https://openalex.org/W2142813783","https://openalex.org/W2145310492","https://openalex.org/W2145511413","https://openalex.org/W2145867514","https://openalex.org/W2146347006","https://openalex.org/W2149176482","https://openalex.org/W2155655319","https://openalex.org/W2156357108","https://openalex.org/W2158695872","https://openalex.org/W2159369772","https://openalex.org/W2159668072","https://openalex.org/W2162593906","https://openalex.org/W2185938598","https://openalex.org/W2217896605","https://openalex.org/W2402955625","https://openalex.org/W2407142979","https://openalex.org/W2725374515","https://openalex.org/W2963373768","https://openalex.org/W2963695034","https://openalex.org/W4238539449","https://openalex.org/W4285719527","https://openalex.org/W6675224631","https://openalex.org/W6675736572","https://openalex.org/W6678466122","https://openalex.org/W6679449023","https://openalex.org/W6680779366","https://openalex.org/W6680813480","https://openalex.org/W6681191503","https://openalex.org/W6681551814","https://openalex.org/W6681749294","https://openalex.org/W6682714106","https://openalex.org/W6682788232","https://openalex.org/W6686523527","https://openalex.org/W6713566895","https://openalex.org/W6740801418"],"related_works":["https://openalex.org/W2350751952","https://openalex.org/W1999647744","https://openalex.org/W2362114017","https://openalex.org/W3147024994","https://openalex.org/W2063246903","https://openalex.org/W2374055396","https://openalex.org/W1978302214","https://openalex.org/W2021817983","https://openalex.org/W1995039490","https://openalex.org/W2104382484"],"abstract_inverted_index":{"Over":[0],"the":[1,80,83,115,126,136,139,179,185,202,206],"last":[2,173],"decade,":[3],"human":[4,209],"facial":[5,70],"expressions":[6,49,57,71],"recognition":[7,72,190],"(FER)":[8],"has":[9],"emerged":[10],"as":[11],"an":[12],"important":[13],"research":[14,22],"area.":[15],"Several":[16],"factors":[17],"make":[18],"FER":[19],"a":[20,59,65,86,94,111,133,172],"challenging":[21],"problem.":[23],"These":[24],"include":[25],"varying":[26],"light":[27,91],"conditions":[28],"in":[29],"training":[30],"and":[31,37,44,106,109],"test":[32],"images;":[33],"need":[34],"for":[35,159,208],"automatic":[36,96],"accurate":[38],"face":[39,97],"detection":[40,98],"before":[41],"feature":[42],"extraction;":[43],"high":[45,60,118],"similarity":[46,119],"among":[47,120],"different":[48,121,150,196],"that":[50,129],"makes":[51],"it":[52],"dif\ufb01cult":[53],"to":[54,75,89,102,113,177],"distinguish":[55],"these":[56,77],"with":[58],"accuracy.":[61],"This":[62],"work":[63],"implements":[64],"hierarchical":[66],"linear":[67],"discriminant":[68],"analysis-based":[69],"(HL-FER)":[73],"system":[74],"tackle":[76],"problems.":[78],"Unlike":[79,123],"previous":[81,127],"systems,":[82],"HL-FER":[84,112,140,186,207],"uses":[85],"pre-processing":[87],"step":[88],"eliminate":[90],"effects,":[92],"incorporates":[93],"new":[95],"scheme,":[99],"employs":[100],"methods":[101],"extract":[103],"both":[104],"global":[105],"local":[107],"features,":[108],"utilizes":[110],"overcome":[114],"problem":[116],"of":[117,125,138,175,181,184,192,204],"expressions.":[122],"most":[124],"works":[128],"were":[130],"evaluated":[131],"using":[132,143,198],"single":[134],"dataset,":[135],"performance":[137],"is":[141],"assessed":[142],"three":[144,149,195,199],"publicly":[145],"available":[146],"datasets":[147],"under":[148],"experimental":[151],"settings:":[152],"n-fold":[153,163],"cross":[154,164],"validation":[155,165],"based":[156,167],"on":[157,168],"subjects":[158],"each":[160,182],"dataset":[161],"separately;":[162],"rule":[166],"datasets;":[169],"and,":[170],"\ufb01nally,":[171],"set":[174],"experiments":[176],"assess":[178],"effectiveness":[180],"module":[183],"separately.":[187],"Weighted":[188],"average":[189],"accuracy":[191],"98.7%":[193],"across":[194],"datasets,":[197],"classifiers,":[200],"indicates":[201],"success":[203],"employing":[205],"FER.":[210]},"counts_by_year":[{"year":2024,"cited_by_count":1},{"year":2022,"cited_by_count":6},{"year":2021,"cited_by_count":3},{"year":2020,"cited_by_count":5},{"year":2019,"cited_by_count":2},{"year":2018,"cited_by_count":3},{"year":2017,"cited_by_count":5},{"year":2016,"cited_by_count":5},{"year":2015,"cited_by_count":5},{"year":2014,"cited_by_count":3}],"updated_date":"2026-03-20T23:20:44.827607","created_date":"2025-10-10T00:00:00"}