Take a picture of a thin-layer chromatography plate, an agarose or SDS-PAGE gel, or a western blot, or open a PNG, a JPEG or a PDF from a scanner. Fit four corners and it is straightened, however it was photographed.
On a TLC plate the origin, the front and the spots are found, with their Rf. On a gel the lanes and the bands are found, and a ladder from the catalogue gives every band its size.
Straighten a picture of a thin-layer chromatography plate, mark its spots and read every Rf value, then weigh its eluent on a solvent scale. The tool needs JavaScript, because the picture is read in your browser.