On June 4th a cold front was advancing towards Czechia with thick Ci/Cs cloud cover ahead of the front.
Zbyněk Černoch was keeping an eye for any potential halos that might show up. As soon as the cloud cover started to sublimate (it was nicely visible on satellite imagery), bright pyramidal plate arcs showed up. The 23° parhelion is very easily distinguishable with its characteristic shape.
A few moments later, the 23° parhelion lost its initial shape, but became a little more coloured.
The same photos, with B-R processing: