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Expose linear transform feature of libvips (#1024)

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Marcel
2018-02-04 11:36:04 +01:00
committed by Lovell Fuller
parent 73edfb3d2c
commit d599d1f29e
15 changed files with 156 additions and 1 deletions
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79
test/unit/linear.js Normal file
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'use strict';
const sharp = require('../../');
const fixtures = require('../fixtures');
const assert = require('assert');
describe('Linear adjustment', function () {
const blackPoint = 70;
const whitePoint = 203;
const a = 255 / (whitePoint - blackPoint);
const b = -blackPoint * a;
it('applies linear levels adjustment w/o alpha ch', function (done) {
sharp(fixtures.inputJpgWithLowContrast)
.linear(a, b)
.toBuffer(function (err, data, info) {
if (err) throw err;
fixtures.assertSimilar(fixtures.expected('low-contrast-linear.jpg'), data, done);
});
});
it('applies slope level adjustment w/o alpha ch', function (done) {
sharp(fixtures.inputJpgWithLowContrast)
.linear(a)
.toBuffer(function (err, data, info) {
if (err) throw err;
fixtures.assertSimilar(fixtures.expected('low-contrast-slope.jpg'), data, done);
});
});
it('applies offset level adjustment w/o alpha ch', function (done) {
sharp(fixtures.inputJpgWithLowContrast)
.linear(null, b)
.toBuffer(function (err, data, info) {
if (err) throw err;
fixtures.assertSimilar(fixtures.expected('low-contrast-offset.jpg'), data, done);
});
});
it('applies linear levels adjustment w alpha ch', function (done) {
sharp(fixtures.inputPngOverlayLayer1)
.linear(a, b)
.toBuffer(function (err, data, info) {
if (err) throw err;
fixtures.assertSimilar(fixtures.expected('alpha-layer-1-fill-linear.png'), data, done);
});
});
it('applies slope level adjustment w alpha ch', function (done) {
sharp(fixtures.inputPngOverlayLayer1)
.linear(a)
.toBuffer(function (err, data, info) {
if (err) throw err;
fixtures.assertSimilar(fixtures.expected('alpha-layer-1-fill-slope.png'), data, done);
});
});
it('applies offset level adjustment w alpha ch', function (done) {
sharp(fixtures.inputPngOverlayLayer1)
.linear(null, b)
.toBuffer(function (err, data, info) {
if (err) throw err;
fixtures.assertSimilar(fixtures.expected('alpha-layer-1-fill-offset.png'), data, done);
});
});
it('Invalid linear arguments', function () {
assert.throws(function () {
sharp(fixtures.inputPngOverlayLayer1)
.linear('foo');
});
assert.throws(function () {
sharp(fixtures.inputPngOverlayLayer1)
.linear(undefined, { 'bar': 'baz' });
});
});
});