High-quality　and　cost-efficient　image　upscaling　design　is　very　important　for　many　real-time　video　processing　applications,　especially　when　the　display　panel　resolution　reaches　ultrahigh　definition.　Compared　with　New　Edge-Directed　Interpolation　(NEDI)　based　implicit　edge　directional　upscaling,　explicit　methods　require　less　computational　resource　and　more　easily　reach　real-time　performance,　especially　when　the　required　image　definition　and　upscaling　ratio　are　very　high.　Nevertheless,　the　investigation　of　applications　of　explicit　methods　in　video　processing　systems　remains　largely　missing　arguably　because　it　is　commonly　believed　that　explicit　edge-directed　interpolation　tends　to　introduce　unexpected　artifacts　because　of　inaccurate　detection　and　hence　its　image　quality　is　relatively　poor.　This　paper　proposes　an　explicit　edge-directed　adaptive　interpolation　method　that　leverages　more　sophisticated　edge　detection　and　orientation　estimation　algorithms　to　avoid　misinterpolation,　thereby　providing　similar　or　even　better　image　quality　than　those　with　implicit　methods.　Targeting　the　real-time　4K　video　display　system,　the　proposed　edge-directed　image　upscaling　algorithm　is　further　implemented　with　an　efficient　very-large-scale　integration　(VLSI)　architecture.　The　experimental　results　demonstrate　that　the　proposed　interpolation　algorithm　outperforms　previous　explicit　and　implicit　edge-directed　methods　in　both　objective　and　subjective　tests.　The　presented　VLSI　implementation　further　demonstrates　that　the　maximum　output　video　sequence　of　the　proposed　interpolation　method　can　reach　4k　x　2k@60　Hz　with　a　reasonable　hardware　cost.