diff --git a/lib/api_2captcha/client.rb b/lib/api_2captcha/client.rb
index d3a03a0..9a63102 100644
--- a/lib/api_2captcha/client.rb
+++ b/lib/api_2captcha/client.rb
@@ -227,16 +227,24 @@ def file_params(params)
       image = params.delete("image")
       hint_image = params.delete("hint_image")
 
-      image_content = get_image_content(image)
-      hint_image_content = get_image_content(hint_image) if hint_image
+      image_content = if base64_encoded?(image)
+        image
+      else
+        Base64.strict_encode64(get_image_content(image))
+      end
+
+      hint_image_content = if hint_image
+                  base64_encoded?(hint_image) ? hint_image : Base64.strict_encode64(get_image_content(hint_image))
+                  end
+
       result_params = {
         "method" => "base64",
-        "body" => Base64.strict_encode64(image_content),
+        "body" => image_content,
         "filename" => File.basename(image),
         "ext" => File.extname(image).delete(".")
       }
 
-      result_params["imginstructions"] = Base64.strict_encode64(hint_image_content) if hint_image_content
+      result_params["imginstructions"] = hint_image_content if hint_image_content
       params.merge(result_params)
     end
 
@@ -246,6 +254,10 @@ def get_image_content(image)
       image
     end
 
+    def base64_encoded?(string)
+      string.is_a?(String) && string.match(/\A[A-Za-z0-9+\/=]+\z/) && (string.length % 4).zero?
+    end
+
     def download_image(url)
       response = URI.open(url)
       if response.status[0] != '200'