Image regress tests.

regress/image-sixel-palette.sh

@@ -0,0 +1,34 @@
+#!/bin/sh
+
+# Reduce a 512-colour cube to a SIXEL palette. Check colour error, opaque
+# pixels, palette size, extremes and reproducible output after redraws.
+
+PATH=/bin:/usr/bin
+TERM=screen
+export TERM
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+
+python3 -B - "$TEST_TMUX" <<'PY'
+import sys
+from image_test import image_test, sixel
+
+levels = [0, 14, 29, 43, 57, 71, 86, 100]
+palette = [(r, g, b) for r in levels for g in levels for b in levels]
+expected = [tuple((c * 255 + 50) // 100 for c in p) for p in palette]
+with image_test(sys.argv[1]) as test:
+    client = test.attach()
+    test.emit(sixel(32, 16, palette, list(range(512))))
+    images = client.images()
+    assert len(images) == 1 and images[0][:2] == (32, 16)
+    actual = images[0][2]
+    assert all(c is not None for c in actual), 'dithering introduced holes'
+    assert 128 <= len(set(actual)) <= 256, len(set(actual))
+    errors = [abs(a - e) for p, q in zip(actual, expected) for a, e in zip(p, q)]
+    assert max(errors) <= 80, max(errors)
+    assert sum(errors) / len(errors) <= 16, sum(errors) / len(errors)
+    assert max(actual[0]) <= 30 and min(actual[-1]) >= 225, (
+        'black/white extremes lost', actual[0], actual[-1])
+    for _ in range(3):
+        test.redraw()
+        assert client.images() == images, 'palette or dithering changed on redraw'
+PY