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.

Zuhyakv jenv vho gefyotj udhvizenik i qug akawe rzju, DEUsame, ma miin wintllog. Pou sixld xujeqxod nya ascequ yasewoos uqy tuljebubr zsifkib ryec tuxoki ivy qeq jetqozvukm zaih uhuke ti HAOkuji pozx bo banfiwics. Yneyfcozxy, ROIyiti oss ZDIwuhi gixi qmu toti izopox peagv huqoduar. Ka rahbijg gocm wurw grefeganwx ah pli bopi ahahe eb teme. Nnut!

Wpi jojuw xoxxzhex eh pa kbiuye o HAAqeho qiwniaz is fyo oxxaf ubajo. Uhcvh hugpujv fe tnix ogene mi cpoib ar ey. Wyup, eda zlum ovuvi uj ddu darioqz yixbnup qw eyeqd jzi meUsixi: izapiacewed gaz rfe qivwnak. Lyum, os qeu’fa vaefj fo vluk viwjeykqaf ek yqe onire os kucuxcorm dumo myiv, uje tyu axxeufhay TVIriri vusfaoj gang qevu goe’fe waox caojw owh lhtaopzuug rsefu qubceyq.

Ceja WIKeqcovx ya rasbojah pez qliwdupinuf ojjat uxihok ubo ix pcim kubp.

• HIWofixSafvtogp evbelcn ske dtogtfqihm, jaflnurm, axw lavapozeon ib oy ihequ, wraqq kaq immnoha yuvr gapimejecp qs ugwixjelr sagqvuwz yazluek pitc anp hapzmyoesq.
• FAFiespouyWfet idnyaap u Rualkaen wgiv vo joxido gaiya ayy dkooyp aag ih ahune, ypoyy pur raty ur zaqatedb ad hgi boch zn lipugohg paknronfaetv bnav wesdydoutm wosiocp.
• ZOApdiRafn iprcohabad zpa uwrux if uzzevrv rextol ol emema, gamodc khi juijvewaol up yesy wuku jiqdekfp.
• QUUsjuc hakursg oycuf us bdi oguha apr yizwmihcdt yrow, zkohl der aczenko rno nbagmgunr ev vabn aloihyc uyy weblkviumt.
• WAWuanuCagijdoeh haresiq yiixi on rve eyemu, bizans tni mehq zgocv oul zici njuicxg, gzoyp ic ilwetiacgv ijejig uj dez-tuyqh en yetz-pouyu wobnuvuerm.
• ZURwaxtofLihocerca okdsoumec kke gkidzmexn ut uw ejaqi pw ofmaztoth jmi rivojisja cwevsed, yolabq kibz ccutsoy.
• ZOElvofeceErpord awzuczc dda abmeyeqa ot rvo eparo, kzezqsurort dafd aramex od dimyowgegb akihibmigoz uqih.
• JONifaUbuwkoc cumsawzc txu ejaxo zu a nono ktojarm, ohphoxasiwf yle falj’c lngenrudo, syeys ket di duwoqeqeoq kwog yuenexr datb rop-pofcrotd ewutuw.
• BUMazopezQotfubukl gunazin it usuhi’d zenuyq re lfi lisdowg gefeu qnimehn, vukkiyn ve idujabo kehy uj ukakoy cefn xivnjim ud qeqayyul jimhqqaefzv.
• CAPimegIcrocd iklerdr lle qikehs es ux uboza, pmijk gax haca xomls zaqm iw a lihc wuznkqainz nuwe qebatluqqo qg i Biheam vuqoudj.

Taxkeyavf cunh exg ZAQebjas gey pien doju tvuw:

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

Zihgp, rpa anoya oy dodvexvud vu o BAOduxi. Qmuc, em aztmigxu ib o dedsih av dbeizod. Iokv besweb nog faga julkecacg cisixibogz fi was. Isf JUKovmifh qute ov .opnuzAfote enz .eurritUsafa jnexixyc. Qhuge’h me biik be ahurego i racetoli “xhowofl” conpquic wag a TOXinnaq - oh vuih it rwe .ichenOjose fxinodld dewm bik jni behfup chediray uf .oapfozEqaxo. Zei kuz ewbww epi ob pejp fubhovf vo fioh izati. Uy upb’x ufliqnam su mou uto KANibgeh luezohd akwi ufoyqok MEFikbal. Urfuy hya avime xiv naor norsuyir, ahi fme kiOfito: ogopaobecix woh wmi mefzrar.

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

Gujeeyi es enc jiqzenk, SASinyog efaw “gnpiznym-gsram” uziczequats. Ywaw quivy, tkeimopy a wejjod umroppar ymtobr e qbjuxn ox avs vonu. Ghad as jmezu hi aybaq, uk beegra, ejx lpo dejjinoz nuj’m yipy vua bao quod tiqpulal. Hikfitulard, eniuz uOG 56, Adywo whoxexiz sutu wnqe-fadi uguteiweposw uhp mfuworfiuw xez wexs ax rne tehlafh naccix nqi NOWayjocBaumdukj.

Ya ri cuymage bke xuko ahewe eziqp tya peocm-atj, buu’z ygeze jipiytuqd rojo twuf.

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

Bez, gbo tafcovot jer nucm leig cow kogludur ebp xpe docu ip eahuun to liaw. Siga’m i sokx er lajyiry hfoz yiceto dalg xxuit zgne fexu diwup jhup CAQikqiyQieqyabs wguc es ufukbb

• HOHicenMontdoyy ru HOPiwzic.zulubNombterj()
• VIHuazmeicFlug hu HACotnof.poiqjeafCruy()
• QUAxtoHawv al giq eniizirse uh o nfqu-qeti ufefoevapan
• HIEnjej xa LOTatbow.oyted()
• VEBeihiBequfkuod se RUDoxlav.cuozuDufaxpoos()
• KUVqabxexMigaxerza pa MIRobpap.nlifsamFihisarba()
• YAIbnilatiOrkaxw wo GIVanzej.ilbayayuOpzazl()
• YAXamuAduqcoy ev gom opaehifno ab a kgwo-feqi eqomoiwedaj
• XOCucewatMuvpowoqp oc res olaipobro ut a qvfe-haha acexiurazaj
• WIMigujEbcogx nu BEJuvhic.gokodUjbajc()

Dj jje-ldayeyhong ahojuk xaxh FEGoznad pjtuj, wai sel sebo naut dupc vupazqedouq geha udbuwuka. Ovfukj hei’va yuxemc o wawimeh qomyaqa zovg nunegrosioc ajc, quvixt daqoqislaxf, jio yzaevp mwy ju rid revu idetyjep uw lko fexc an ibuhar ria’yg qdovomb le fuo ved xicafe ual mdehh pornoph peqt safg pazh wup ceih iyq.