public com.google.protobuf.ByteString getConfidenceMaskBytes() {
      java.lang.Object ref = confidenceMask_;
      if (ref instanceof String) {
        com.google.protobuf.ByteString b =
            com.google.protobuf.ByteString.copyFromUtf8((java.lang.String) ref);
        confidenceMask_ = b;
        return b;
      } else {
        return (com.google.protobuf.ByteString) ref;
      }
    }
<pre>
A one channel image which is encoded as an 8bit lossless PNG. The size of
the image will be the same as the original image. For a specific pixel,
darker color means less confidence in correctness of the cateogry in the
categoryMask for the corresponding pixel. Black means no confidence and
white means complete confidence.
</pre>

<code>string confidence_mask = 2;</code>

@return The bytes for confidenceMask.
java-visionai/proto-google-cloud-visionai-v1/src/main/java/com/google/cloud/visionai/v1/ImageSegmentationPredictionResult.java