Image Color Summarizer is described as 'The web service provides statistics describing color characteristics of an image identified by URL. Summary data indicate the single RGB color that best represents the image, along with average hue and saturation values and RGB and HSV histograms' and is an website in the education & reference category. There are more than 10 alternatives to Image Color Summarizer, not only websites but also apps for a variety of platforms, including Mac, Linux, Flathub and Flatpak apps. The best Image Color Summarizer alternative is Coloraccy, which is free. Other great sites and apps similar to Image Color Summarizer are Pigment, Colormind, CopyPalette and Paleta.
Goes for pleasing colours rather than actual colours in source images. Also limited to 5, can't move up or down from that.