Got it almost working...

src/graphics/Monochrome.hpp

@@ -31,11 +31,12 @@ class Monochrome {
 
     void setThreshold(uint8_t);
     void invert(bool shouldInvert);
+    void visualize();
     std::vector<uint8_t> get();
 
    private:
     const std::vector<uint8_t>& mPixels;
-    uint8_t mThreshhold = 127;
+    uint8_t mThreshhold = UINT8_MAX / 2;
     bool mShouldInvert  = false;
 };
 }  // namespace ptprnt::graphics