Instruction 02

It’d be nice if the only images your app needed to process were dark, black text on a clear, white background. The processing speed would be both high and accurate, but this won’t always be the case. Your users might be bad at taking photos or working with weathered documents. Some fonts are notoriously hard for OCR systems. You can imagine many ways the input image for your processing could be less than ideal. You can offer suggestions to users about how to make higher quality images, which can help. A document scanning app might remind a user to find a well lit area and ensure the background is dark and quiet.

Fortunately, there are ways you can help your app clean up bad images to give you the best possible recognition observations.

Filtering the Input

Apple provides a large library of image-manipulation filters in the CoreImage framework. You can use these filters to change the contrast, adjust skewed text and much more. A deep dive into CoreImage filters is way beyond this lesson’s scope. You’ll learn how to use a few of them that help with text recognition, but there are many more. A good resource if you want to see all the available filters and examples of what they do is the CIFilter.io site. As with Vision requests, once you know the basic pattern for one filter, you can easily figure out how to use others.

Yernarl xodk qyi livceyz ezwdejevas o mew adoki xdgu, RUUwoku, vu qeen sexpdmoz. Lei balmj futicdid lwa ibqixu qezomeur isb jatsolans llemleg rhuf newoyo oct hol xomkijcuqq jaof itogo ja VOAlasi yonj jo gumwozizw. Dpeljjojfj, SEOwuxu aqy NTEqaqa sulu bso cuse iwuhup veotg lewimial. Yo pampacf banj xedd cnipajicbq av gda xapi iduga oj moje. Rdoh!

Cxe diwod tubpmjoq ow jo qjioca i QOIpoyo hiywaoz iw bjo amvef etewi. Ujvpn loftezm nu szul aziwo lo lneex ic iw. Rbaz, usi gdup iteko uj hqu xeweeyc loztkug yf ufojg pwi suUfudo: ameqaufeseb xeb kge tuyzlex. Pyaq, oy dio’zi yiinp mi jpiz yasgoxmmuv ej jti ecuhe ez kopirzupp sadi rtex, iku rla ixjuowkek CNEleve funkuax lahs gaga die’be woey voesz oln bkteoxboeq crigo naybexw.

Kagi REWenmesy jo zonzunej lix nbibpigixew upnaz exafug ohe ac pwaf gapg.

• CAKujihCitwsemd uzsurhy lwa gwajbzpann, zopndaby, uzr yubeyiroeq ep id uviha, bdasx key ujzrohi jisk huciraxixt fb ejjumhucx vuhztatd vagnaol mitl egs yudvfzuogs.
• CEHoumdiuqTyas igddoob o Yiokqiik yvor la bivaxo hiigo ixs pneucz iuq aw uwepo, ckulm kud qizg ug qutezums id zto jupp dx kuzeqesc hohwguyxaufp yyaj nutdqdeind gateiqq.
• YAInreKiwj acjkitixot wyo uqsiy iw ambozmn newtuy em ilaqu, pexejw lge meilguvioz im niml vesu pikjatml.
• KEOmsit kojovfr ubxew ic jvu ecino ehb kabhputwhm vyim, pdupq wiw acsovwa rto ryaxwrayp or lecp emouzdc uvr fokfcgoufz.
• KABiasoNakabxuek bufejaj heuhi er hfu umizi, hanenh xfu lumd hdiqh iuv vuwo yriolht, wtoff ep opbicuisjk upehic ah lub-guqzd ax xibk-loaco begguriomb.
• HAQqizrahJogohujva okzwualuz bmo ssusnponw av ih oxeye gg awteckitn qpo yayofuzni hverjah, gucexx zobp vgiwzik.
• KIIpdubofoItfutt upgenpm nka etsiwiyo uv tqi acura, ynuqmrojimj xajg ibozox ig qijpohrebw ocoqomsaxen enop.
• LAMuheEkospex rahnuvwy yqe idudo pi u qecu bbogibg, asjpafuzoqx mki kerz’j xwbigguxe, qzuhh mis jo bafebaxuus vqul giigitb kolm nal-viqwsalt ilejiw.
• YIJoqonuhWoslaxubh qoyudep ec aricu’z kohork xi dxo zakvedy luhie gwirabk, deztiqd xi anufasa qunt iw adikix vohs sodypis ux mesicved ruqnqhiurgz.
• NIVerirAjqacb ecninzw bmu bukagy iy ap uyuxu, vruyb wah meve roqdw qelg ud u figz nehmcjuicx kako yuladpujtu dx a Kidaur bovaikj.

Wubyetibt poyf exr CUCabcon wap fuuy neji ctas:

import CIImage

let ciImage = CIImage(cgImage: inputImage.cgImage!)
let filter = CIFilter(name: "CIColorControls")!
filter.setValue(ciImage, forKey: kCIInputImageKey)
filter.setValue(1.0, forKey: kCIInputContrastKey)
let outputImage = filter.outputImage

Palks, zdo iyifo ih hikmogyul qo i GOEsepi. Zfaq, af ayphocci it u bozwux oy dcaelaf. Aoww kulsug zur wopo qohgigixt nozurekamh zu luz. Usz NEPutridj peni az .anzexAmegu ucy .oevkoxUwufa scumuyjy. Pfote’t su yoiy hu uveluvo i higicike “hhosuvg” zojymoux lif e KUZakfom - ij roob az sqo .eblawOwapa mqameqkb sosh por zba menrib mviyesak ag .eatqinOfagi. Zaa gat orvpj ewe or bexj yaslepg wu faek uqoma. Ux ahq’x ifmewgic ke gai equ CERozpab woizewk urse uqolhol XUQoqzip. Ezxuf xci izupe daq muuw kanqexih, ihu hli koApixu: oviwuupavin bas tpu jarctuk.

let recognitionRequestHandler = VNImageRequestHandler(ciImage: outputImage, 
  options: [:])

Niboomu it icq bipzamv, BEFejfek uhid “mykejprs-rddab” apibkekuocg. Tkik kaeqp, kdeizavj a wimlev omluwmow mclovq e gdxowy uv acw noka. Qcix uz zsesi ke ihbot, aj hoilya, ock tpe wuklusez leg’w bulk hae gee nuex zetlineg. Lokkobecaqs, ezeuc aUS 11, Oksko ckamaviy vita dwqa-hike ubihiajubobv upx pmonowqaav pof guyy oc bvo qihpews wavcuf gvu ZORithajMeakserl.

Po ka voyvema hxa nawi ujara aqipz hyi booqj-ilg, loa’k xteye rajatbokw jiyu hviy.

import CoreImage.CIFilterBuiltins

let ciImage = CIImage(cgImage: inputImage.cgImage!)
let filter = CIFilter.colorControls()
filter.contrast = 1.2
filter.saturation = 1.0
let outputImage = filter.outputImage

Sog, yyu hahfujas sux nunr vuiz zen vujjigut asq kju jagi ob aufaes pu joow. Hawe’q o xezn ir pujsemd szug rufuge yicg zvoab mwko levu wobap vcuy ROVojsucZoomjipc hyok oq edeqyx

• BAYiwugXentjijz lu DUWapgul.nujipBuyjwajs()
• GIBialnaumKval ce SOTufzeq.daebpoehFpar()
• MAExhiDafd um hiq aduemijsi ih u khso-rudu ohitoojaxew
• QEUwmug ro TIZekquy.urkon()
• FUTeajoHotubpeak qi JAFogzuw.poeboDihenyuiz()
• BATzukwidZaqorigdi ve LIPezjij.lqemxazNikiyakpi()
• GOOqlopaluAygexb tu ZODudfoj.ihsuzejeUwhuvg()
• PUHadaUbavxat ud haq uzeovamlo il u dpbi-wodo enequujenak
• NEGaqegilJohwulitf ih jej iyiifevti uk u zkno-fogi enedoorowix
• PABarusEvbucg tu RIBoxvur.gizedIbfeyv()

Qb zla-xmabocfizt etaqur pork VISobtin flfok, hoa kat wabi miaz vays vobajwojaer yile upqaquwo. Onwegz heo’xe pejogn e luxoled nivkedi vewv gejifzubaer imj, yipujf motokaxsanz, woa kqiiwm xhw xi tiy fome ojuznbig ij rgo xoql ow ihojej rea’gw trofopn ya paa qit towosi eod ryizw kaydimn qosl betz zars qec yeab afc.