From 5d140d949f73f8bb42f3a090114deb8972dd5b3b Mon Sep 17 00:00:00 2001
From: Nathan Graves <woolite64@users.noreply.github.com>
Date: Thu, 26 Apr 2018 11:49:08 -0700
Subject: [PATCH] Add support for Group4 (CCITTFAX4) compression to TIFF output
 (#1208)

---
 docs/api-output.md |  2 +-
 lib/output.js      |  4 ++--
 test/unit/io.js    | 16 ++++++++++++++++
 3 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/docs/api-output.md b/docs/api-output.md
index 4f37602a..0f97e86d 100644
--- a/docs/api-output.md
+++ b/docs/api-output.md
@@ -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`)
diff --git a/lib/output.js b/lib/output.js
index 528c2028..878a3ac3 100644
--- a/lib/output.js
+++ b/lib/output.js
@@ -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);
     }
   }
diff --git a/test/unit/io.js b/test/unit/io.js
index 64d5d496..59209214 100644
--- a/test/unit/io.js
+++ b/test/unit/io.js
@@ -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)