# Test record

By [Sergey Quantum](https://paragraph.com/@sergey-quantum) · 2023-07-09

---

Two reasons why the EHT black hole image on the right is better:

*   The PCA method captures correlations and fills in the gaps in highly sparse data better
    
*   A Butterworth filter was used before PCA, which approximates the data more accurately
    
    < [https://doi.org/10.3847/2041-8213/acc32d>](https://doi.org/10.3847/2041-8213/acc32d%3E)

---

*Originally published on [Sergey Quantum](https://paragraph.com/@sergey-quantum/test-record)*