Draw­ing on long years at the easel

China Daily (Hong Kong) - - CHINA - By CHENG YINGQI

While com­put­ers are more ef­fi­cient than peo­ple at stor­ing in­for­ma­tion and re­triev­ing it quickly, the hu­man brain’s pri­mary strength lies in us­ing the imag­i­na­tion to fill in the blanks when in­for­ma­tion is miss­ing.

That’s why po­lice de­part­ments still need peo­ple such as Lin Yuhui, an artist who can draw an ac­cu­rate sketch of a sus­pect even when se­cu­rity cam­eras fail to cap­ture a clear im­age.

Lin’s skill lies in iden­ti­fy­ing clues that en­able him to pro­duce an al­most faith­ful like­ness, ei­ther from blurred photos or cam­era sur­veil­lance footage that shows just 25 per­cent of a per­son’s face.

“As long as in­com­plete or blurred photos con­tain a cer­tain amount of in­for­ma­tion about fea­tures such as the eyes, chin or nose, my ex­pe­ri­ence al­lows me to work out the rest for my­self,” he said.

Lin has sketched about 70,000 faces, mainly peo­ple he has ob­served in pub­lic places such as rail­way sta­tions.

The in­for­ma­tion he gar­nered en­abled him to sort them into eight cat­e­gories and cre­ate a “data­base” of typ­i­cal Chi­nese faces.

“In the past when there was no cam­era sur­veil­lance, most of the in­for­ma­tion re­lat­ing to a sus­pect’s im­age was pro­vided by vic­tims of crime, which pro­vided very vague and some­times in­ac­cu­rate de­scrip­tions,” he said.

As a coun­ter­mea­sure, Lin shows vic­tims his hand-painted data­base in the hope of jog­ging their mem­o­ries.

His of­fice at the Pub­lic Se­cu­rity Depart­ment in Shan­dong prov­ince is al­ways crowded with po­lice of­fi­cers from across China look­ing for guid­ance.

Lin also uses fa­cial fea­tures that re­main rel­a­tively un­changed over time to cre­ate por­traits of miss­ing chil­dren.

“Some par­ents are search­ing for their chil­dren with photos taken five or six years ago. Be­cause chil­dren grow quickly, those old pic­tures may not help the par­ents to find the child, so I draw sketches of the child at dif­fer­ent ages, which is a bet­ter way of help­ing,” he said.

Mei Lin, di­rec tor of the Cy­ber Phys­i­cal Sys­tem R&D Cen­ter at the Min­istr y of Pub­lic Se­cu­rity ’s T hird Re­search In­sti­tute, said de­part­ments t hat use fa­cial­recog­ni­tion tech­nol­ogy need to co­op­er­ate with ex­pe­ri­enced ex­perts such as Lin to im­prove the qual­ity of their work.

“We are con­sid­er­ing work­ing with po­lice artists to see whether it is pos­si­ble to use their ex­pe­ri­ence of re­cov­er­ing fa­cial im­ages to im­prove our com­put­ers’ i mage­pro­cess­ing ca­pac­i­ties,” he said.

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