diff --git a/src/display/editor/stamp.js b/src/display/editor/stamp.js
index fc4f6e41c68bb..0381f475651ed 100644
--- a/src/display/editor/stamp.js
+++ b/src/display/editor/stamp.js
@@ -133,9 +133,52 @@ class StampEditor extends AnnotationEditor {
     ) {
       this._editToolbar.hide();
       this._uiManager.editAltText(this, /* firstTime = */ true);
-    } else {
-      this.div.focus();
+      return;
     }
+
+    if (
+      !this._uiManager.useNewAltTextWhenAddingImage &&
+      this._uiManager.useNewAltTextFlow &&
+      this.#bitmap
+    ) {
+      // The alt-text dialog isn't opened but we still want to guess the alt
+      // text.
+      this.mlGuessAltText();
+    }
+
+    this.div.focus();
+  }
+
+  async mlGuessAltText(imageData = null, updateAltTextData = true) {
+    if (this.hasAltTextData()) {
+      return null;
+    }
+
+    const { mlManager } = this._uiManager;
+    if (!mlManager || !(await mlManager.isEnabledFor("altText"))) {
+      return null;
+    }
+    const { data, width, height } =
+      imageData ||
+      this.copyCanvas(null, /* createImageData = */ true).imageData;
+    const response = await mlManager.guess({
+      name: "altText",
+      request: {
+        data,
+        width,
+        height,
+        channels: data.length / (width * height),
+      },
+    });
+    if (!response || response.error || !response.output) {
+      return null;
+    }
+    const altText = response.output;
+    await this.setGuessedAltText(altText);
+    if (updateAltTextData && !this.hasAltTextData()) {
+      this.altTextData = { alt: altText, decorative: false };
+    }
+    return altText;
   }
 
   #getBitmap() {
@@ -370,6 +413,13 @@ class StampEditor extends AnnotationEditor {
   }
 
   copyCanvas(maxDimension, createImageData = false) {
+    if (!maxDimension) {
+      // TODO: get this value from Firefox
+      //   (https://bugzilla.mozilla.org/show_bug.cgi?id=1908184)
+      // It's the maximum dimension that the AI can handle.
+      maxDimension = 224;
+    }
+
     const { width: bitmapWidth, height: bitmapHeight } = this.#bitmap;
     const canvas = document.createElement("canvas");
 
diff --git a/src/display/editor/tools.js b/src/display/editor/tools.js
index a45f3647144f0..436dc0c4d6f41 100644
--- a/src/display/editor/tools.js
+++ b/src/display/editor/tools.js
@@ -856,18 +856,6 @@ class AnnotationEditorUIManager {
     }
   }
 
-  hasMLManager() {
-    return !!this.#mlManager;
-  }
-
-  async mlGuess(data) {
-    return this.#mlManager?.guess(data) || null;
-  }
-
-  async isMLEnabledFor(name) {
-    return !!(await this.#mlManager?.isEnabledFor(name));
-  }
-
   get mlManager() {
     return this.#mlManager;
   }
diff --git a/web/new_alt_text_manager.js b/web/new_alt_text_manager.js
index 9f372bda59359..a89ac4575b054 100644
--- a/web/new_alt_text_manager.js
+++ b/web/new_alt_text_manager.js
@@ -240,29 +240,17 @@ class NewAltTextManager {
 
     let hasError = false;
     try {
-      const { width, height, data } = this.#imageData;
-
-      // Take a reference on the current editor, as it can be set to null (if
-      // the dialog is closed before the end of the guess).
-      // But in case we've an alt-text, we want to set it on the editor.
-      const editor = this.#currentEditor;
-
       // When calling #mlGuessAltText we don't wait for it, so we must take care
       // that the alt text dialog can have been closed before the response is.
-      const response = await this.#uiManager.mlGuess({
-        name: "altText",
-        request: {
-          data,
-          width,
-          height,
-          channels: data.length / (width * height),
-        },
-      });
-      if (!response || response.error || !response.output) {
+
+      const altText = await this.#currentEditor.mlGuessAltText(
+        this.#imageData,
+        /* updateAltTextData = */ false
+      );
+      if (altText === null) {
         throw new Error("No valid response from the AI service.");
       }
-      const altText = (this.#guessedAltText = response.output);
-      await editor.setGuessedAltText(altText);
+      this.#guessedAltText = altText;
       this.#wasAILoading = this.#isAILoading;
       if (this.#isAILoading) {
         this.#addAltText(altText);