  Obtaining high-resolution images at centimeter-or-longer wavelengths is vital
for understanding the physics of jets. We reconstructed images from the M87 22
GHz data observed with the East Asian VLBI Network (EAVN) by using the
regularized maximum likelihood (RML) method, which is different from the
conventional imaging method CLEAN. Consequently, a bright core and jet
extending about 30 mas to the northwest were detected with a higher resolution
than in the CLEAN image. The width of the jet was 0.5 mas at 0.3 mas from the
core, consistent with the width measured in the 86 GHz image in the previous
study. In addition, three ridges were able to be detected at around 8 mas from
the core, even though the peak-to-peak separation was only 1.0 mas. This
indicates that the RML image's spatial resolution is at least 30% higher than
that of the CLEAN image. This study is an important step for future
multi-frequency and high-cadence observations of the EAVN to discuss the more
detailed structure of the jet and its time variability.
