Vim muaj kev nce qib ntawm kev txhim kho ntawm cov ntaub ntawv thev naus laus zis, txhua xyoo cov ntaub ntawv hluav taws xob tau yooj yim dua thiab xav tau hauv kev siv thiab tab tom pib ua tus thawj coj ntawm cov ntawv xov xwm. Yog li ntawd, nws yog ib qho tseem ceeb heev uas yuav tsum tau them sai sai rau kev tiv thaiv cov ntsiab lus ntawm cov ntaub ntawv tsis yog ntawm cov ntawv xov xwm ib txwm muaj, tab sis kuj tseem muaj cov ntaub ntawv hluav taws xob. Txhua lub tuam txhab loj uas muaj kev lag luam, xeev thiab lwm yam kev zais cia xav tiv thaiv kom tsis txhob muaj cov ntaub ntawv xau thiab kev cuam tshuam ntawm cov ntaub ntawv cais tawm, thiab yog tias pom muaj cov pa xau, ntsuas ntsuas los tiv thaiv cov xau thiab txheeb xyuas tus neeg ua txhaum cai.
Ib me ntsis txog kev tiv thaiv kev xaiv
Txhawm rau ua cov haujlwm no, qee yam kev tiv thaiv tau qhia. Xws li cov ntsiab lus tuaj yeem yog barcodes, pom cov cim npe, cov cim hluav taws xob, tab sis qhov nthuav tshaj plaws yog cov cim zais. Ib qho ntawm cov neeg sawv cev zoo tshaj plaws yog watermarks; lawv tuaj yeem siv rau hauv ntawv lossis ntxiv ua ntej luam tawm ntawm lub tshuab luam ntawv. Nws tsis muaj qhov zais cia uas cov tshuab luam ntawv tso lawv tus kheej cov cim dej (daj dots thiab lwm cov cim) thaum luam ntawv, tab sis peb yuav xav txog lwm yam khoom qub uas tuaj yeem muab tso rau ntawm lub khoos phis tawj ntawm cov neeg ua haujlwm qhov chaw ua haujlwm. Cov khoom qub zoo li no yog tsim los ntawm cov pob software tshwj xeeb uas rub cov khoom cuav rau saum tus neeg siv qhov chaw ua haujlwm, txo qis qhov pom ntawm cov khoom cuav lawv tus kheej thiab tsis cuam tshuam rau tus neeg siv txoj haujlwm. Cov thev naus laus zis no muaj keeb kwm yav dhau los hauv cov ntsiab lus ntawm kev tshawb fawb thiab cov algorithms siv los nthuav qhia cov ntaub ntawv zais, tab sis tsis tshua muaj nyob hauv lub ntiaj teb niaj hnub no. Txoj hauv kev no feem ntau pom muaj nyob hauv tub rog thiab ntawm daim ntawv, rau kev txheeb xyuas tam sim ntawm cov neeg ua haujlwm tsis zoo. Cov thev naus laus zis no nyuam qhuav pib nkag mus rau hauv ib puag ncig kev lag luam. Pom pom watermarks tam sim no tau nquag siv los tiv thaiv cov cai ntawm ntau cov ntaub ntawv xov xwm, tab sis qhov pom tsis tshua muaj tsawg. Tab sis lawv kuj ua rau muaj kev txaus siab tshaj plaws.
Kev ruaj ntseg Artifacts
Pom tsis tau rau tib neeg Watermarks tsim ntau yam khoom qub uas tuaj yeem ua tau, hauv txoj ntsiab cai, pom tsis tau rau tib neeg lub qhov muag, thiab tuaj yeem npog cov duab hauv daim duab me me. Peb yuav xav txog cov khoom pom, txij li cov uas pom tsis tau ntawm lub qhov muag yuav nyob sab nraum cov qauv xim ntawm cov saib feem ntau. Cov khoom qub no muaj txiaj ntsig tshwj xeeb vim lawv qhov siab ntawm kev pom tsis pom. Txawm li cas los xij, nws tsis tuaj yeem ua rau CEHs pom tsis tau kiag li. Nyob rau hauv tus txheej txheem ntawm lawv cov kev siv, ib yam ntawm distortion ntawm lub thawv duab yog nkag mus rau hauv cov duab, thiab ib co artifacts tshwm sim rau nws. Cia peb xav txog 2 hom khoom:
- Cyclical
- Chaotic (qhia los ntawm kev hloov pauv duab)
Cov ntsiab lus Cyclic sawv cev rau qee qhov kev txiav txim siab ntawm cov ntsiab lus rov qab uas tau rov ua dua ntau dua ib zaug ntawm cov duab tshuaj ntsuam (Daim duab 1).
Chaotic artifacts tuaj yeem tshwm sim los ntawm ntau hom kev hloov pauv ntawm cov duab overlaid (Daim duab 2), piv txwv li, kev taw qhia ntawm hologram.
Rice. 1 Cycling artifacts
Rice. 2 Chaotic Artifacts
Ua ntej, cia peb saib cov kev xaiv rau kev paub txog cov khoom siv dag zog. Xws li artifacts tuaj yeem yog:
- ntawv watermarks rov ua dua nyob rau ntawm qhov screen
- binary sequences
- ib txheej ntawm chaotic ntsiab lus nyob rau hauv txhua daim phiaj cell
Tag nrho cov khoom pov thawj uas tau teev tseg yog siv ncaj qha rau saum cov ntsiab lus tso tawm; raws li, lawv tuaj yeem raug lees paub los ntawm kev txheeb xyuas lub zos extrema ntawm histogram ntawm txhua cov xim channel thiab, raws li, txiav tawm tag nrho lwm cov xim. Txoj kev no suav nrog kev ua haujlwm nrog kev sib txuas ntawm qhov chaw hauv cheeb tsam ntawm txhua qhov histogram raws. Qhov teeb meem nyob ntawm kev tshawb nrhiav hauv zos extrema nyob rau hauv ib tug ncaj complex duab nrog ntau sharply hloov cov ntsiab lus; lub histogram zoo li sawtooth heev, uas ua rau txoj kev no siv tsis tau. Koj tuaj yeem sim siv ntau cov ntxaij lim dej, tab sis lawv yuav qhia lawv tus kheej distortions, uas thaum kawg yuav ua rau tsis muaj peev xwm txheeb xyuas cov cim dej. Kuj tseem muaj qhov kev xaiv ntawm kev paub txog cov khoom cuav no siv qee cov khoom siv ntug (piv txwv li, Canny edge detector). Cov txheej txheem no muaj lawv qhov chaw rau artifacts uas yog heev ntse nyob rau hauv kev hloov; detectors muaj peev xwm highlight cov duab contours thiab tom qab ntawd xaiv xim ntau yam nyob rau hauv lub contours rau binarize cov duab nyob rau hauv thiaj li yuav ntxiv highlight cov artifacts lawv tus kheej, tab sis cov txheej txheem no yuav tsum tau kom haum zoo tuning rau highlight lub xav tau contours, nrog rau tom qab binarization ntawm daim duab nws tus kheej txheeb ze rau cov xim hauv cov contours xaiv. Cov algorithms no suav hais tias yog qhov tsis ntseeg siab thiab sim siv ntau qhov ruaj khov thiab ywj pheej ntawm hom xim ntawm cov duab.
Rice. 3 Watermark tom qab hloov dua siab tshiab
Raws li rau chaotic artifacts tau hais ua ntej, cov algorithms rau kev lees paub lawv yuav txawv heev. Txij li thaum tsim ntawm chaotic artifacts yog xam los ntawm imposing ib tug tej yam watermark rau ntawm daim duab, uas yog hloov los ntawm ib co ntawm cov transformations (piv txwv li, discrete Fourier transform). Artifacts los ntawm cov kev hloov pauv no tau muab faib thoob plaws tag nrho lub vijtsam thiab nws nyuaj rau txheeb xyuas lawv cov qauv. Raws li qhov no, watermark yuav nyob thoob plaws hauv daim duab hauv daim ntawv ntawm "random" artifacts. Kev lees paub ntawm qhov dej cim no los mus rau kev hloov pauv duab ncaj qha siv cov haujlwm hloov pauv. Qhov tshwm sim ntawm kev hloov pauv tau nthuav tawm hauv daim duab (Fig. 3).
Tab sis ib tug xov tooj ntawm cov teeb meem tshwm sim uas tiv thaiv watermark paub nyob rau hauv tsawg tshaj li qhov zoo tagnrho tej yam kev mob. Nyob ntawm seb hom kev hloov dua siab tshiab, tej zaum yuav muaj ntau yam teeb meem, piv txwv li, qhov tsis tuaj yeem lees paub ntawm cov ntaub ntawv tau txais los ntawm kev yees duab ntawm lub kaum sab xis loj ntawm lub vijtsam, lossis tsuas yog daim duab ntawm qhov tsis zoo, lossis ib qho screen capture khaws cia hauv ib cov ntaub ntawv nrog siab poob compression. Tag nrho cov teeb meem no ua rau muaj teeb meem ntawm kev txheeb xyuas tus watermark; nyob rau hauv cov ntaub ntawv ntawm ib tug angled duab, nws yog tsim nyog los thov ib tug complex transformations los yog siv affine transformations rau daim duab, tab sis tsis guarantees tag nrho cov restoration ntawm watermark. Yog tias peb xav txog qhov xwm txheej ntawm qhov screen capture, ob qhov teeb meem tshwm sim: thawj zaug yog distortion thaum tso tawm ntawm qhov screen nws tus kheej, qhov thib ob yog distortion thaum txuag cov duab ntawm lub vijtsam nws tus kheej. Thawj yog qhov nyuaj heev rau kev tswj hwm vim tias muaj cov matrices rau kev saib xyuas ntawm qhov sib txawv, thiab vim tsis muaj ib lossis lwm yam xim, lawv cuam tshuam cov xim nyob ntawm lawv cov xim sawv cev, yog li qhia distortions rau hauv watermark nws tus kheej. Qhov thib ob yog qhov nyuaj dua, vim qhov tseeb tias koj tuaj yeem txuag lub screenshot hauv txhua hom thiab, raws li, poob ib feem ntawm cov xim ntau yam, yog li ntawd, peb tuaj yeem tsuas poob lub watermark nws tus kheej.
Teeb meem kev siv
Nyob rau hauv lub ntiaj teb niaj hnub no, muaj ntau ntau algorithms rau qhia watermarks, tab sis tsis muaj ib tug guarantee 100% muaj peev xwm ntawm ntxiv kev paub txog watermark tom qab nws siv. Qhov teeb meem tseem ceeb yog kev txiav txim siab txog cov txheej txheem ntawm kev yug me nyuam uas yuav tshwm sim hauv txhua kis. Raws li tau hais ua ntej, nws yog qhov nyuaj los tsim kom muaj kev lees paub algorithm uas yuav coj mus rau hauv tus account tag nrho cov yam ntxwv ntawm distortion thiab sim ua kom puas lub watermark. Piv txwv li, yog tias Gaussian lim tau siv rau cov duab tam sim no, thiab cov khoom qub hauv cov duab qub tau me me thiab sib txawv ntawm cov duab keeb kwm yav dhau, ces nws yuav tsis tuaj yeem lees paub lawv, lossis ib feem ntawm cov cim dej yuav ploj. . Cia peb xav txog qhov xwm txheej ntawm daim duab, nrog rau qhov muaj feem ntau nws yuav muaj moire (Fig. 5) thiab "daim phiaj" (Fig. 4). Moire tshwm sim vim qhov tsis sib xws ntawm lub vijtsam matrix thiab qhov tsis sib xws ntawm matrix ntawm cov cuab yeej kaw; nyob rau hauv qhov xwm txheej no, ob daim duab mesh yog superimposed rau ib leeg. Cov mesh feem ntau yuav yog ib feem npog cov khoom kos duab kos duab thiab ua rau muaj teeb meem kev paub; moire, dhau los, hauv qee qhov kev kos duab kos ua rau nws tsis tuaj yeem lees paub nws, txij li nws sib tshooj ib feem ntawm daim duab nrog watermark.
Rice. 4 Daim phiaj duab
Rice. 5 Moore
Txhawm rau txhawm rau txhawm rau txhawm rau paub txog cov cim dej, nws yog qhov yuav tsum tau siv cov algorithms raws li kev kawm ntawm tus kheej neural networks thiab hauv cov txheej txheem ntawm kev ua haujlwm, uas lawv tus kheej yuav kawm paub txog cov duab watermark. Tam sim no muaj ntau cov cuab yeej neural network thiab cov kev pabcuam, piv txwv li, los ntawm Google. Yog xav tau, koj tuaj yeem nrhiav cov duab siv los qhia thiab qhia cov neural network kom paub txog cov khoom tsim nyog. Txoj hauv kev no muaj txoj hauv kev zoo tshaj plaws rau kev txheeb xyuas txawm tias cov dej tsis sib haum xeeb heev, tab sis rau kev txheeb xyuas ceev nws yuav tsum muaj lub zog suav loj thiab lub sijhawm kawm ntev heev rau kev txheeb xyuas kom raug.
Txhua yam piav qhia zoo li yooj yim heev, tab sis qhov tob koj nkag mus rau hauv cov teeb meem no, qhov ntau koj nkag siab tias kom paub txog cov cim watermarks koj yuav tsum siv sijhawm ntau rau kev siv ib qho ntawm cov algorithms, thiab ntau lub sijhawm los coj nws mus rau qhov yuav tsum tau muaj. paub txog txhua daim duab.
Tau qhov twg los: www.hab.com