Plot graphs from JSON files produced by libvmaf (VMAF/MS_SSIM/PSNR).
Plots show metric scores per frame, not per video. A line represents a single video, not multiple encdoings using the same encoder.
One way to obtain those files is by using the vmafossexec with
the arguments --psnr --ms-ssim --log-fmt json. The tool is usually
packaged with libvmaf.
gnuplot is used for plotting, with PNG files as output.