Color image quality depends on many factors, such as the initial capture system and its color image processing, compression, transmission, the output device, media and associated viewing conditions. In this paper, we are primarily concerned with color image quality in relation to compression and transmission. We review the typical visual artifacts that occur due to high compression ratios and/or transmission errors. We discuss color image quality metrics and present no-reference artifact metrics for blockiness, blurriness, and colorfulness. We show that these metrics are highly correlated with experimental data collected through subjective experiments. We use them for no-reference video quality assessment in different compression and transmission scenarios and again obtain very good results. We conclude by discussing the important effects viewing conditions can have on image quality.