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Add support for Group4 (CCITTFAX4) compression to TIFF output (#1208)

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This commit is contained in:
Nathan Graves 2018-04-26 11:49:08 -07:00 committed by Lovell Fuller
parent 6d2da2b3ba
commit 5d140d949f
3 changed files with 19 additions and 3 deletions
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2
docs/api-output.md
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@ -213,7 +213,7 @@ Use these TIFF options for output image.
- `options` **[Object][15]?** output options
- `options.quality` **[Number][18]** quality, integer 1-100 (optional, default `80`)
- `options.force` **[Boolean][16]** force TIFF output, otherwise attempt to use input format (optional, default `true`)
- `options.compression` **[Boolean][16]** compression options: lzw, deflate, jpeg (optional, default `'jpeg'`)
- `options.compression` **[Boolean][16]** compression options: lzw, deflate, jpeg, ccittfax4 (optional, default `'jpeg'`)
- `options.predictor` **[Boolean][16]** compression predictor options: none, horizontal, float (optional, default `'horizontal'`)
- `options.xres` **[Number][18]** horizontal resolution in pixels/mm (optional, default `1.0`)
- `options.yres` **[Number][18]** vertical resolution in pixels/mm (optional, default `1.0`)

4
lib/output.js
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@ -326,10 +326,10 @@ function tiff (options) {
}
// compression
if (is.defined(options) && is.defined(options.compression)) {
if (is.string(options.compression) && is.inArray(options.compression, ['lzw', 'deflate', 'jpeg', 'none'])) {
if (is.string(options.compression) && is.inArray(options.compression, ['lzw', 'deflate', 'jpeg', 'ccittfax4', 'none'])) {
this.options.tiffCompression = options.compression;
} else {
const message = `Invalid compression option "${options.compression}". Should be one of: lzw, deflate, jpeg, none`;
const message = `Invalid compression option "${options.compression}". Should be one of: lzw, deflate, jpeg, ccittfax4, none`;
throw new Error(message);
}
}

16
test/unit/io.js
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@ -1083,6 +1083,22 @@ describe('Input/output', function () {
});
});
it('TIFF ccittfax4 compression shrinks b-w test file', function (done) {
const startSize = fs.statSync(fixtures.inputTiff).size;
sharp(fixtures.inputTiff)
.toColourspace('b-w')
.tiff({
squash: true,
compression: 'ccittfax4'
})
.toFile(fixtures.outputTiff, (err, info) => {
if (err) throw err;
assert.strictEqual('tiff', info.format);
assert(info.size < startSize);
fs.unlink(fixtures.outputTiff, done);
});
});
it('TIFF deflate compression with horizontal predictor shrinks test file', function (done) {
const startSize = fs.statSync(fixtures.inputTiffUncompressed).size;
sharp(fixtures.inputTiffUncompressed)