Bug 1782579 - Pass languages to the text recognition api; r=nordzilla,emilio

Differential Revision: https://phabricator.services.mozilla.com/D153668

dom/base/nsImageLoadingContent.cpp

@@ -52,6 +52,8 @@
 #include "mozilla/dom/ImageTextBinding.h"
 #include "mozilla/dom/ImageTracker.h"
 #include "mozilla/dom/ScriptSettings.h"
+#include "mozilla/intl/LocaleService.h"
+#include "mozilla/intl/Locale.h"
 #include "mozilla/net/UrlClassifierFeatureFactory.h"
 #include "mozilla/widget/TextRecognition.h"
 
@@ -1232,60 +1234,98 @@ already_AddRefed<Promise> nsImageLoadingContent::RecognizeCurrentImageText(
     return nullptr;
   }
 
-  TextRecognition::FindText(*image)->Then(
-      GetCurrentSerialEventTarget(), __func__,
-      [weak = RefPtr{do_GetWeakReference(this)},
-       request = RefPtr{mCurrentRequest}, domPromise](
-          TextRecognition::NativePromise::ResolveOrRejectValue&& aValue) {
-        if (aValue.IsReject()) {
-          domPromise->MaybeRejectWithNotSupportedError(aValue.RejectValue());
-          return;
-        }
-        RefPtr<nsIImageLoadingContent> iilc = do_QueryReferent(weak.get());
-        if (!iilc) {
-          domPromise->MaybeRejectWithInvalidStateError(
-              "Element was dead when we got the results");
-          return;
-        }
-        auto* ilc = static_cast<nsImageLoadingContent*>(iilc.get());
-        if (ilc->mCurrentRequest != request) {
-          domPromise->MaybeRejectWithInvalidStateError("Request not current");
-          return;
-        }
-        auto& textRecognitionResult = aValue.ResolveValue();
-        Element* el = ilc->AsContent()->AsElement();
+  // The list of ISO 639-1 language tags to pass to the text recognition API.
+  AutoTArray<nsCString, 4> languages;
+  {
+    // The document's locale should be the top language to use. Parse the BCP 47
+    // locale and extract the ISO 639-1 language tag. e.g. "en-US" -> "en".
+    nsAutoCString elementLanguage;
+    nsAtom* imgLanguage = AsContent()->GetLang();
+    intl::Locale locale;
+    if (imgLanguage) {
+      imgLanguage->ToUTF8String(elementLanguage);
+      auto result = intl::LocaleParser::TryParse(elementLanguage, locale);
+      if (result.isOk()) {
+        languages.AppendElement(locale.Language().Span());
+      }
+    }
+  }
 
-        // When enabled, this feature will place the recognized text as spans
-        // inside of the shadow dom of the img element. These are then
-        // positioned so that the user can select the text.
-        if (Preferences::GetBool("dom.text-recognition.shadow-dom-enabled",
-                                 false)) {
-          el->AttachAndSetUAShadowRoot(Element::NotifyUAWidgetSetup::Yes);
-          TextRecognition::FillShadow(*el->GetShadowRoot(),
-                                      textRecognitionResult);
-          el->NotifyUAWidgetSetupOrChange();
-        }
+  {
+    // The app locales should also be included after the document's locales.
+    // Extract the language tag like above.
+    nsTArray<nsCString> appLocales;
+    intl::LocaleService::GetInstance()->GetAppLocalesAsBCP47(appLocales);
 
-        nsTArray<ImageText> imageTexts(textRecognitionResult.quads().Length());
-        nsIGlobalObject* global = el->OwnerDoc()->GetOwnerGlobal();
+    for (const auto& localeString : appLocales) {
+      intl::Locale locale;
+      auto result = intl::LocaleParser::TryParse(localeString, locale);
+      if (result.isErr()) {
+        NS_WARNING("Could not parse an app locale string, ignoring it.");
+        continue;
+      }
+      languages.AppendElement(locale.Language().Span());
+    }
+  }
 
-        for (const auto& quad : textRecognitionResult.quads()) {
-          NotNull<ImageText*> imageText = imageTexts.AppendElement();
+  TextRecognition::FindText(*image, languages)
+      ->Then(
+          GetCurrentSerialEventTarget(), __func__,
+          [weak = RefPtr{do_GetWeakReference(this)},
+           request = RefPtr{mCurrentRequest}, domPromise](
+              TextRecognition::NativePromise::ResolveOrRejectValue&& aValue) {
+            if (aValue.IsReject()) {
+              domPromise->MaybeRejectWithNotSupportedError(
+                  aValue.RejectValue());
+              return;
+            }
+            RefPtr<nsIImageLoadingContent> iilc = do_QueryReferent(weak.get());
+            if (!iilc) {
+              domPromise->MaybeRejectWithInvalidStateError(
+                  "Element was dead when we got the results");
+              return;
+            }
+            auto* ilc = static_cast<nsImageLoadingContent*>(iilc.get());
+            if (ilc->mCurrentRequest != request) {
+              domPromise->MaybeRejectWithInvalidStateError(
+                  "Request not current");
+              return;
+            }
+            auto& textRecognitionResult = aValue.ResolveValue();
+            Element* el = ilc->AsContent()->AsElement();
 
-          // Note: These points are not actually CSSPixels, but a DOMQuad is
-          // a conveniently similar structure that can store these values.
-          CSSPoint points[4];
-          points[0] = CSSPoint(quad.points()[0].x, quad.points()[0].y);
-          points[1] = CSSPoint(quad.points()[1].x, quad.points()[1].y);
-          points[2] = CSSPoint(quad.points()[2].x, quad.points()[2].y);
-          points[3] = CSSPoint(quad.points()[3].x, quad.points()[3].y);
+            // When enabled, this feature will place the recognized text as
+            // spans inside of the shadow dom of the img element. These are then
+            // positioned so that the user can select the text.
+            if (Preferences::GetBool("dom.text-recognition.shadow-dom-enabled",
+                                     false)) {
+              el->AttachAndSetUAShadowRoot(Element::NotifyUAWidgetSetup::Yes);
+              TextRecognition::FillShadow(*el->GetShadowRoot(),
+                                          textRecognitionResult);
+              el->NotifyUAWidgetSetupOrChange();
+            }
 
-          imageText->mQuad = new DOMQuad(global, points);
-          imageText->mConfidence = quad.confidence();
-          imageText->mString = quad.string();
-        }
-        domPromise->MaybeResolve(std::move(imageTexts));
-      });
+            nsTArray<ImageText> imageTexts(
+                textRecognitionResult.quads().Length());
+            nsIGlobalObject* global = el->OwnerDoc()->GetOwnerGlobal();
+
+            for (const auto& quad : textRecognitionResult.quads()) {
+              NotNull<ImageText*> imageText = imageTexts.AppendElement();
+
+              // Note: These points are not actually CSSPixels, but a DOMQuad is
+              // a conveniently similar structure that can store these values.
+              CSSPoint points[4];
+              points[0] = CSSPoint(quad.points()[0].x, quad.points()[0].y);
+              points[1] = CSSPoint(quad.points()[1].x, quad.points()[1].y);
+              points[2] = CSSPoint(quad.points()[2].x, quad.points()[2].y);
+              points[3] = CSSPoint(quad.points()[3].x, quad.points()[3].y);
+
+              imageText->mQuad = new DOMQuad(global, points);
+              imageText->mConfidence = quad.confidence();
+              imageText->mString = quad.string();
+            }
+            domPromise->MaybeResolve(std::move(imageTexts));
+          });
   return domPromise.forget();
 }
 

dom/ipc/ContentParent.cpp

@@ -4965,23 +4965,25 @@ mozilla::ipc::IPCResult ContentParent::RecvCopyFavicon(
 }
 
 mozilla::ipc::IPCResult ContentParent::RecvFindImageText(
-    ShmemImage&& aImage, FindImageTextResolver&& aResolver) {
+    ShmemImage&& aImage, nsTArray<nsCString>&& aLanguages,
+    FindImageTextResolver&& aResolver) {
   RefPtr<DataSourceSurface> surf =
       nsContentUtils::IPCImageToSurface(std::move(aImage), this);
   if (!surf) {
     aResolver(TextRecognitionResultOrError("Failed to read image"_ns));
     return IPC_OK();
   }
-  TextRecognition::FindText(*surf)->Then(
-      GetCurrentSerialEventTarget(), __func__,
-      [resolver = std::move(aResolver)](
-          TextRecognition::NativePromise::ResolveOrRejectValue&& aValue) {
-        if (aValue.IsResolve()) {
-          resolver(TextRecognitionResultOrError(aValue.ResolveValue()));
-        } else {
-          resolver(TextRecognitionResultOrError(aValue.RejectValue()));
-        }
-      });
+  TextRecognition::FindText(*surf, aLanguages)
+      ->Then(
+          GetCurrentSerialEventTarget(), __func__,
+          [resolver = std::move(aResolver)](
+              TextRecognition::NativePromise::ResolveOrRejectValue&& aValue) {
+            if (aValue.IsResolve()) {
+              resolver(TextRecognitionResultOrError(aValue.ResolveValue()));
+            } else {
+              resolver(TextRecognitionResultOrError(aValue.RejectValue()));
+            }
+          });
   return IPC_OK();
 }
 

dom/ipc/ContentParent.h

@@ -1110,7 +1110,7 @@ class ContentParent final : public PContentParent,
   mozilla::ipc::IPCResult RecvCopyFavicon(nsIURI* aOldURI, nsIURI* aNewURI,
                                           const bool& aInPrivateBrowsing);
 
-  mozilla::ipc::IPCResult RecvFindImageText(ShmemImage&&,
+  mozilla::ipc::IPCResult RecvFindImageText(ShmemImage&&, nsTArray<nsCString>&&,
                                             FindImageTextResolver&&);
 
   virtual void ProcessingError(Result aCode, const char* aMsgName) override;

dom/ipc/PContent.ipdl

@@ -1237,7 +1237,8 @@ parent:
 
     async CopyFavicon(nsIURI oldURI, nsIURI newURI, bool isPrivate);
 
-    async FindImageText(ShmemImage image) returns (TextRecognitionResultOrError result);
+    async FindImageText(ShmemImage image, nsCString[] languages)
+        returns (TextRecognitionResultOrError result);
 
     /**
      * Notifies the parent about a recording device is starting or shutdown.

toolkit/content/tests/widgets/chrome.ini

@@ -2,6 +2,7 @@
 skip-if = os == 'android'
 support-files =
   image.png
+  image-zh.png
   tree_shared.js
   popup_shared.js
   window_label_checkbox.xhtml
@@ -15,6 +16,10 @@ skip-if = os == 'linux' # Bug 1115088
 [test_editor_currentURI.xhtml]
 [test_image_recognition.html]
 run-if = os == "mac" # Mac only feature.
+[test_image_recognition_unsupported.html]
+skip-if = os == 'mac'
+[test_image_recognition_zh.html]
+run-if = os == "mac" && os_version != "10.15" # Mac only feature, requires > 10.15 to support multilingual results.
 [test_label_checkbox.xhtml]
 [test_menubar.xhtml]
 skip-if = os == 'mac'

toolkit/content/tests/widgets/test_image_recognition.html

@@ -4,8 +4,8 @@
   <title>Image recognition test</title>
   <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
   <script src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"></script>
-  <script type="text/javascript" src="head.js"></script>
-  <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css" />
+  <script src="head.js"></script>
+  <link rel="stylesheet" href="chrome://mochikit/content/tests/SimpleTest/test.css" />
 </head>
 <body>
 <p id="display"></p>
@@ -15,11 +15,10 @@
 </div>
 
 <pre id="test">
-<script class="testbody" type="text/javascript">
+<script class="testbody">
   const { TestUtils } = ChromeUtils.import(
     "resource://testing-common/TestUtils.jsm"
   );
-  SimpleTest.waitForExplicitFinish();
 
   function pushPref(preferenceName, value) {
     return new Promise(resolve => {
@@ -28,41 +27,39 @@
     });
   }
 
-  window.addEventListener("load", async () => {
-    try {
-      await pushPref("dom.text-recognition.shadow-dom-enabled", true);
-      const img = document.querySelector("#content img");
+  add_task(async () => {
+    // Performing text recognition in CI can take some time, and test verify runs have
+    // timed out.
+    SimpleTest.requestLongerTimeout(2);
 
-      info("Recognizing the image text");
-      const result = await img.recognizeCurrentImageText();
-      is(result.length, 2, "Two words were found.");
-      const mozilla = result.find(r => r.string === "Mozilla");
-      const firefox = result.find(r => r.string === "Firefox");
+    await pushPref("dom.text-recognition.shadow-dom-enabled", true);
+    const img = document.querySelector("#content img");
 
-      ok(mozilla, "The word Mozilla was found.");
-      ok(firefox, "The word Firefox was found.");
+    info("Recognizing the image text");
+    const result = await img.recognizeCurrentImageText();
+    is(result.length, 2, "Two words were found.");
+    const mozilla = result.find(r => r.string === "Mozilla");
+    const firefox = result.find(r => r.string === "Firefox");
 
-      ok(mozilla.quad.p1.x < firefox.quad.p2.x, "The Mozilla text is left of Firefox");
-      ok(mozilla.quad.p1.y > firefox.quad.p2.y, "The Mozilla text is above Firefox");
+    ok(mozilla, "The word Mozilla was found.");
+    ok(firefox, "The word Firefox was found.");
 
-      const spans = await TestUtils.waitForCondition(
-        () => shadowRootQuerySelectorAll(img, "span"),
-        "Attempting to get image recognition spans."
-      );
+    ok(mozilla.quad.p1.x < firefox.quad.p2.x, "The Mozilla text is left of Firefox");
+    ok(mozilla.quad.p1.y > firefox.quad.p2.y, "The Mozilla text is above Firefox");
 
-      const mozillaSpan = [...spans].find(s => s.innerText === "Mozilla");
-      const firefoxSpan = [...spans].find(s => s.innerText === "Firefox");
+    const spans = await TestUtils.waitForCondition(
+      () => shadowRootQuerySelectorAll(img, "span"),
+      "Attempting to get image recognition spans."
+    );
 
-      ok(mozillaSpan, "The word Mozilla span was found.");
-      ok(firefoxSpan, "The word Firefox span was found.");
+    const mozillaSpan = [...spans].find(s => s.innerText === "Mozilla");
+    const firefoxSpan = [...spans].find(s => s.innerText === "Firefox");
 
-      ok(mozillaSpan.style.transform.startsWith("matrix3d("), "A matrix transform was applied");
-      ok(firefoxSpan.style.transform.startsWith("matrix3d("), "A matrix transform was applied");
-    } catch (error) {
-      ok(false, error.message + '\n' + error.stack);
-    }
+    ok(mozillaSpan, "The word Mozilla span was found.");
+    ok(firefoxSpan, "The word Firefox span was found.");
 
-    SimpleTest.finish()
+    ok(mozillaSpan.style.transform.startsWith("matrix3d("), "A matrix transform was applied");
+    ok(firefoxSpan.style.transform.startsWith("matrix3d("), "A matrix transform was applied");
   });
 </script>
 </pre>

toolkit/content/tests/widgets/test_image_recognition_unsupported.html

@@ -0,0 +1,36 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Image recognition unsupported</title>
+  <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"></script>
+  <script src="head.js"></script>
+  <link rel="stylesheet" href="chrome://mochikit/content/tests/SimpleTest/test.css" />
+</head>
+<body>
+<p id="display"></p>
+
+<div id="content">
+  <img src="image.png" />
+</div>
+
+<pre id="test">
+<script class="testbody">
+  /**
+   * This test is for platforms that do not support text recognition.
+   */
+  add_task(async () => {
+    const img = document.querySelector("#content img");
+
+    info("Recognizing the current image text is not supported on this platform.");
+    try {
+      await img.recognizeCurrentImageText();
+      ok(false, "Recognizing the text should not be supported.");
+    } catch (error) {
+      ok(error, "Expected unsupported message: " + error.message);
+    }
+  });
+</script>
+</pre>
+</body>
+</html>

toolkit/content/tests/widgets/test_image_recognition_zh.html

@@ -0,0 +1,53 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Image recognition test for Chinese</title>
+  <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"></script>
+  <script src="head.js"></script>
+  <link rel="stylesheet" href="chrome://mochikit/content/tests/SimpleTest/test.css" />
+</head>
+<body>
+<p id="display"></p>
+
+<div id="content">
+  <img src="image-zh.png" />
+</div>
+
+<pre id="test">
+<script class="testbody">
+  // Performing text recognition in CI can take some time, and test verify runs have
+  // timed out.
+  SimpleTest.requestLongerTimeout(2);
+
+  /**
+   * This test exercises the code path where the image recognition APIs detect the
+   * document language and use it to choose the language.
+   */
+  add_task(async () => {
+    const img = document.querySelector("#content img");
+
+    info("Recognizing the image text, but not as Chinese");
+    {
+      const result = await img.recognizeCurrentImageText();
+      for (const { string } of result) {
+        isnot(string, "火狐", 'The results are (as expected) incorrect, as Chinese was not set as the language.');
+      }
+    }
+
+    info("Setting the document to Chinese.");
+    document.documentElement.setAttribute("lang", "zh-Hans-CN");
+
+    info("Recognizing the image text");
+    {
+      const result = await img.recognizeCurrentImageText();
+      is(result.length, 1, "One word was found.");
+      is(result[0].string, "火狐", "The Chinese characters for Firefox are found.");
+    }
+
+    document.documentElement.setAttribute("lang", "en-US");
+  });
+</script>
+</pre>
+</body>
+</html>

widget/TextRecognition.cpp

@@ -14,7 +14,9 @@ using namespace mozilla::dom;
 
 namespace mozilla::widget {
 
-auto TextRecognition::FindText(imgIContainer& aImage) -> RefPtr<NativePromise> {
+auto TextRecognition::FindText(imgIContainer& aImage,
+                               const nsTArray<nsCString>& aLanguages)
+    -> RefPtr<NativePromise> {
   // TODO: Maybe decode async.
   RefPtr<gfx::SourceSurface> surface = aImage.GetFrame(
       imgIContainer::FRAME_CURRENT,
@@ -27,10 +29,11 @@ auto TextRecognition::FindText(imgIContainer& aImage) -> RefPtr<NativePromise> {
     return NativePromise::CreateAndReject("Failed to get data surface"_ns,
                                           __func__);
   }
-  return FindText(*dataSurface);
+  return FindText(*dataSurface, aLanguages);
 }
 
-auto TextRecognition::FindText(gfx::DataSourceSurface& aSurface)
+auto TextRecognition::FindText(gfx::DataSourceSurface& aSurface,
+                               const nsTArray<nsCString>& aLanguages)
     -> RefPtr<NativePromise> {
   if (XRE_IsContentProcess()) {
     auto* contentChild = ContentChild::GetSingleton();
@@ -40,31 +43,32 @@ auto TextRecognition::FindText(gfx::DataSourceSurface& aSurface)
                                             __func__);
     }
     auto promise = MakeRefPtr<NativePromise::Private>(__func__);
-    contentChild->SendFindImageText(*image)->Then(
-        GetCurrentSerialEventTarget(), __func__,
-        [promise](TextRecognitionResultOrError&& aResultOrError) {
-          switch (aResultOrError.type()) {
-            case TextRecognitionResultOrError::Type::TTextRecognitionResult:
-              promise->Resolve(
-                  std::move(aResultOrError.get_TextRecognitionResult()),
-                  __func__);
-              break;
-            case TextRecognitionResultOrError::Type::TnsCString:
-              promise->Reject(std::move(aResultOrError.get_nsCString()),
-                              __func__);
-              break;
-            default:
-              MOZ_ASSERT_UNREACHABLE("Unknown result?");
-              promise->Reject("Unknown error"_ns, __func__);
-              break;
-          }
-        },
-        [promise](mozilla::ipc::ResponseRejectReason) {
-          promise->Reject("IPC rejection"_ns, __func__);
-        });
+    contentChild->SendFindImageText(*image, aLanguages)
+        ->Then(
+            GetCurrentSerialEventTarget(), __func__,
+            [promise](TextRecognitionResultOrError&& aResultOrError) {
+              switch (aResultOrError.type()) {
+                case TextRecognitionResultOrError::Type::TTextRecognitionResult:
+                  promise->Resolve(
+                      std::move(aResultOrError.get_TextRecognitionResult()),
+                      __func__);
+                  break;
+                case TextRecognitionResultOrError::Type::TnsCString:
+                  promise->Reject(std::move(aResultOrError.get_nsCString()),
+                                  __func__);
+                  break;
+                default:
+                  MOZ_ASSERT_UNREACHABLE("Unknown result?");
+                  promise->Reject("Unknown error"_ns, __func__);
+                  break;
+              }
+            },
+            [promise](mozilla::ipc::ResponseRejectReason) {
+              promise->Reject("IPC rejection"_ns, __func__);
+            });
     return promise;
   }
-  return DoFindText(aSurface);
+  return DoFindText(aSurface, aLanguages);
 }
 
 void TextRecognition::FillShadow(ShadowRoot& aShadow,
@@ -101,7 +105,8 @@ void TextRecognition::FillShadow(ShadowRoot& aShadow,
 }
 
 #ifndef XP_MACOSX
-auto TextRecognition::DoFindText(gfx::DataSourceSurface&)
+auto TextRecognition::DoFindText(gfx::DataSourceSurface&,
+                                 const nsTArray<nsCString>&)
     -> RefPtr<NativePromise> {
   MOZ_RELEASE_ASSERT(XRE_IsParentProcess(),
                      "This should only run in the parent process");

widget/TextRecognition.h

@@ -34,12 +34,15 @@ class TextRecognition final {
 
   static void FillShadow(dom::ShadowRoot&, const dom::TextRecognitionResult&);
 
-  static RefPtr<NativePromise> FindText(imgIContainer&);
-  static RefPtr<NativePromise> FindText(gfx::DataSourceSurface&);
+  static RefPtr<NativePromise> FindText(imgIContainer&,
+                                        const nsTArray<nsCString>&);
+  static RefPtr<NativePromise> FindText(gfx::DataSourceSurface&,
+                                        const nsTArray<nsCString>&);
 
  protected:
   // This should be implemented in the OS specific file.
-  static RefPtr<NativePromise> DoFindText(gfx::DataSourceSurface&);
+  static RefPtr<NativePromise> DoFindText(gfx::DataSourceSurface&,
+                                          const nsTArray<nsCString>&);
 
   ~TextRecognition() = default;
 };

widget/cocoa/TextRecognition.mm

@@ -17,7 +17,8 @@
 
 namespace mozilla::widget {
 
-auto TextRecognition::DoFindText(gfx::DataSourceSurface& aSurface) -> RefPtr<NativePromise> {
+auto TextRecognition::DoFindText(gfx::DataSourceSurface& aSurface,
+                                 const nsTArray<nsCString>& aLanguages) -> RefPtr<NativePromise> {
   NS_OBJC_BEGIN_TRY_IGNORE_BLOCK
   if (@available(macOS 10.15, *)) {
     // TODO - Is this the most efficient path? Maybe we can write a new
@@ -30,11 +31,19 @@ auto TextRecognition::DoFindText(gfx::DataSourceSurface& aSurface) -> RefPtr<Nat
 
     auto promise = MakeRefPtr<NativePromise::Private>(__func__);
 
+    NSMutableArray* recognitionLanguages = [[NSMutableArray alloc] init];
+    for (const auto& locale : aLanguages) {
+      [recognitionLanguages addObject:nsCocoaUtils::ToNSString(locale)];
+    }
+
     NS_DispatchBackgroundTask(
         NS_NewRunnableFunction(
             __func__,
-            [promise, imageRef] {
-              auto unrefImage = MakeScopeExit([&] { ::CGImageRelease(imageRef); });
+            [promise, imageRef, recognitionLanguages] {
+              auto unrefImage = MakeScopeExit([&] {
+                ::CGImageRelease(imageRef);
+                [recognitionLanguages release];
+              });
 
               dom::TextRecognitionResult result;
               dom::TextRecognitionResult* pResult = &result;
@@ -67,6 +76,10 @@ auto TextRecognition::DoFindText(gfx::DataSourceSurface& aSurface) -> RefPtr<Nat
                         }];
                   }];
 
+              textRecognitionRequest.recognitionLevel = VNRequestTextRecognitionLevelAccurate;
+              textRecognitionRequest.recognitionLanguages = recognitionLanguages;
+              textRecognitionRequest.usesLanguageCorrection = true;
+
               // Send out the request. This blocks execution of this thread with an expensive
               // CPU call.
               NSError* error = nil;