diff --git a/src/display/editor/stamp.js b/src/display/editor/stamp.js
index ab08dcf0c5172..a57b522f27b69 100644
--- a/src/display/editor/stamp.js
+++ b/src/display/editor/stamp.js
@@ -441,26 +441,22 @@ class StampEditor extends AnnotationEditor {
         width,
         height
       );
-      offscreen.convertToBlob().then(blob => {
-        const fileReader = new FileReader();
-        fileReader.onload = () => {
-          const url = fileReader.result;
-          this._uiManager
-            .mlGuess({
-              service: "image-to-text",
-              request: {
-                imageData: url,
-              },
-            })
-            .then(response => {
-              const altText = response?.output || "";
-              if (this.parent && altText && !this.hasAltText()) {
-                this.altTextData = { altText, decorative: false };
-              }
-            });
-        };
-        fileReader.readAsDataURL(blob);
-      });
+      this._uiManager
+        .mlGuess({
+          service: "image-to-text",
+          request: {
+            data: ctx.getImageData(0, 0, width, height).data,
+            width,
+            height,
+            channels: 4,
+          },
+        })
+        .then(response => {
+          const altText = response?.output || "";
+          if (this.parent && altText && !this.hasAltText()) {
+            this.altTextData = { altText, decorative: false };
+          }
+        });
     }
     const ctx = canvas.getContext("2d");
     ctx.filter = this._uiManager.hcmFilter;