66 lines
3.6 KiB
C
66 lines
3.6 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "dsp/tty/quant.h"
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#include "libc/testlib/testlib.h"
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struct TtyRgb res;
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TEST(rgb2ansi, testDesaturatedPurple_isQuantizedBetterThanEuclideanDistance) {
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ttyquantsetup(kTtyQuantXterm256, kTtyQuantRgb, kTtyBlocksUnicode);
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/*
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* the challenge to the xterm256 palette is that it was likely
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* intended for just syntax highlighting, rather than accurately
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* modeling the natural phenomenon of illumination.
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*
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* as a syntax highlighting palette, it focuses mostly on bright
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* saturated colors, while also providing a really good greyscale for
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* everything else.
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*
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* as such, if one were to project the colors of this palette into a
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* three-dimensional space, we might see something like an HSV cone,
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* where all the color samples are projected mostly around the outside
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* of the cone, and the greyscale dots tracing through the middle.
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*
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* if we want to convert an a real color into an xterm color, we can
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* use euclidean distance functions to pick the closest color, such as
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* sum of squared distance. however this will only work well if it's
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* either a pure grey color, or a bright saturated one.
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*
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* but euclidean distance doesnt work well for the sorts of colors
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* that are generally used for things like film, which conservatively
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* edits for the colors more towards the middle of the space; and as
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* such, which basically causes the distance function to pick greys
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* for almost everything.
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*/
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res = rgb2tty(0x56, 0x38, 0x66);
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/* EXPECT_NE(0x4e, res.r); */
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/* EXPECT_NE(0x4e, res.g); */
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/* EXPECT_NE(0x4e, res.b); */
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/* EXPECT_NE(239, res.xt); */
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/* EXPECT_EQ(0x5f, res.r); */
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/* EXPECT_EQ(0x00, res.g); */
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/* EXPECT_EQ(0x5f, res.b); */
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/* EXPECT_EQ(53, res.xt); */
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}
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