Every picture is built twice: once in value, once in colour.
Value: the painter's value study. Flat grey planes, colour taken away.
Colour: the colour study. Flat colour planes all at the same value, so only the colour relationships are left. Dark lines mark shapes that exist only in colour.
Both: the drawing. Graphite where light draws an edge, the colours themselves where only colour does: the edges that vanish in your value study.
Live on the camera. Hold to see the photo; the button freezes a frame to save.
Runs on this device; pictures never leave it. From the Image Structure Reader.