A plotting program like matplotlib can take data point coordinates and generate, say, a scatter plot and a best fit line. The plot can then be saved as an image in a number of different formats. A vector graphics format such as SVG represents the plot as a list of primitive shapes, storing location/size/color/etc. for each. A raster format, on the other hand, translates that primitive information into color values over a grid of pixels.

In creating publication-quality figures, it is good to preserve vector format until the layout is finalized. A plot that has already been rasterized will appear grainy when zoomed in. The graphics editor Inkscape is adept at editing vector graphics. Images can be scaled or transformed without loss of information. Outer SVG plot elements like axis labels can be removed when combining plots to form a panel figure. The entire thing can then be both rasterized and saved in vector format for future tweaking.