Picture credits
The drawings are our own. The photos are from Wikimedia Commons, under Creative Commons licences (Attribution, or Attribution-ShareAlike), CC0, or in the public domain.
Photos
Our own drawings
- Two panels side by side: a mid-grey square on a near-black background and an identical mid-grey square on a pale background. The one on black looks lighter.
Our own drawing - Two panels: an identical grey square on a red background and on a green background. On red the grey looks slightly greenish; on green it looks slightly pinkish.
Our own drawing - Our own checkerboard scene: a green cylinder stands on a grey checkerboard and casts a round shadow. Square A is a dark square in the light; square B is a light square in the shadow. B looks much lighter than A.
Our own drawing - Black and white horizontal stripes, with short grey bars: on the left the grey bars sit on the black stripes, on the right on the white stripes. The left bars look lighter.
Our own drawing - A wide panel shading smoothly from dark grey on the left to light grey on the right, with a purple line underneath showing the real brightness: flat, a straight ramp, then flat.
Our own drawing - Three pale discs behind grids of thin coloured lines: blue and green lines over the left disc, red and blue over the middle one, red and green over the right one.
Our own drawing - Horizontal stripes of blue and yellow. Orange bars sit on the yellow stripes on the left and on the blue stripes on the right: the left set looks redder, the right set looks yellower.
Our own drawing - Three wavy circles drawn with a purple outer line and a thin orange inner line. Inside, the white paper looks faintly orange.
Our own drawing - Sixteen black lines radiating outwards from an empty centre; near the centre each line turns green. A pale green glowing disc seems to fill the middle.
Our own drawing - A flag of turquoise, black and yellow stripes with a dot to stare at
Our own drawing - Twelve pink blobs in a ring around a cross
Our own drawing - Benham’s top: half black, half white with black arcs
Our own drawing - Our drawing of five strawberries on a tart, all under a strong turquoise tint. The strawberries look reddish even though they are drawn in grey.
Our own drawing - Two copies of the same striped swatch, pale blue and brown stripes. On the left it sits in bright yellowish surroundings; on the right in bluish shadow.
Our own drawing
The drawings are simplified teaching drawings, not to scale, made from the sourced descriptions on this site. Useless the eraser is the network’s own mascot. Fonts: Bricolage Grotesque, Newsreader and Kalam (SIL Open Font Licence), served from this site.