  Ground-based solar observations are severely affected by Earth's turbulent
atmosphere. As a consequence, observed image quality and prevailing seeing
conditions are closely related. Partial correction of image degradation is
nowadays provided in real-time by adaptive optics (AO) systems. In this study,
different metrics of image quality are compared with parameters characterizing
the prevailing seeing conditions, i.e., Median Filter Gradient Similarity
(MFGS), Median Filter Laplacian Similarity (MFLS), Helmli-Scherer mean,
granular rms-contrast, differential image motion, and Fried-parameter r0. The
quiet-Sun observations at disk center were carried out at the Vacuum Tower
Telescope (VTT), Observatorio del Teide (OT), Izana, Tenerife, Spain. In July
and August 2016, time-series of short-exposure images were recorded with the
High-resolution Fast Imager (HiFI) at various wavelengths in the visible and
near-infrared parts of the spectrum. Correlation analysis yields the wavelength
dependence of the image quality metrics and seeing parameters, and Uniform
Manifold Approximation and Projection (UMAP) is employed to characterize the
seeing on a particular observing day. In addition, the image quality metrics
and seeing parameters are used to determine the field-dependence of the
correction provided by the AO system. Management of high-resolution imaging
data from large-aperture, ground-based telescopes demands reliable image
quality metrics and meaningful characterization of prevailing seeing conditions
and AO performance. The present study offers guidance how to retrieve such
information ex post facto.
