Update dependencies (#1610)

* Update dependencies

* Update module to go 1.17

7 files changed, 0 insertions, 1725 deletions

diff --git a/vendor/golang.org/x/image/tiff/buffer.go b/vendor/golang.org/x/image/tiff/buffer.go
deleted file mode 100644
index d1801be4..00000000
--- a/vendor/golang.org/x/image/tiff/buffer.go
+++ /dev/null
@@ -1,69 +0,0 @@
-// Copyright 2011 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package tiff
-
-import "io"
-
-// buffer buffers an io.Reader to satisfy io.ReaderAt.
-type buffer struct {
-	r   io.Reader
-	buf []byte
-}
-
-// fill reads data from b.r until the buffer contains at least end bytes.
-func (b *buffer) fill(end int) error {
-	m := len(b.buf)
-	if end > m {
-		if end > cap(b.buf) {
-			newcap := 1024
-			for newcap < end {
-				newcap *= 2
-			}
-			newbuf := make([]byte, end, newcap)
-			copy(newbuf, b.buf)
-			b.buf = newbuf
-		} else {
-			b.buf = b.buf[:end]
-		}
-		if n, err := io.ReadFull(b.r, b.buf[m:end]); err != nil {
-			end = m + n
-			b.buf = b.buf[:end]
-			return err
-		}
-	}
-	return nil
-}
-
-func (b *buffer) ReadAt(p []byte, off int64) (int, error) {
-	o := int(off)
-	end := o + len(p)
-	if int64(end) != off+int64(len(p)) {
-		return 0, io.ErrUnexpectedEOF
-	}
-
-	err := b.fill(end)
-	return copy(p, b.buf[o:end]), err
-}
-
-// Slice returns a slice of the underlying buffer. The slice contains
-// n bytes starting at offset off.
-func (b *buffer) Slice(off, n int) ([]byte, error) {
-	end := off + n
-	if err := b.fill(end); err != nil {
-		return nil, err
-	}
-	return b.buf[off:end], nil
-}
-
-// newReaderAt converts an io.Reader into an io.ReaderAt.
-func newReaderAt(r io.Reader) io.ReaderAt {
-	if ra, ok := r.(io.ReaderAt); ok {
-		return ra
-	}
-	return &buffer{
-		r:   r,
-		buf: make([]byte, 0, 1024),
-	}
-}
diff --git a/vendor/golang.org/x/image/tiff/compress.go b/vendor/golang.org/x/image/tiff/compress.go
deleted file mode 100644
index 3f176f00..00000000
--- a/vendor/golang.org/x/image/tiff/compress.go
+++ /dev/null
@@ -1,58 +0,0 @@
-// Copyright 2011 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package tiff
-
-import (
-	"bufio"
-	"io"
-)
-
-type byteReader interface {
-	io.Reader
-	io.ByteReader
-}
-
-// unpackBits decodes the PackBits-compressed data in src and returns the
-// uncompressed data.
-//
-// The PackBits compression format is described in section 9 (p. 42)
-// of the TIFF spec.
-func unpackBits(r io.Reader) ([]byte, error) {
-	buf := make([]byte, 128)
-	dst := make([]byte, 0, 1024)
-	br, ok := r.(byteReader)
-	if !ok {
-		br = bufio.NewReader(r)
-	}
-
-	for {
-		b, err := br.ReadByte()
-		if err != nil {
-			if err == io.EOF {
-				return dst, nil
-			}
-			return nil, err
-		}
-		code := int(int8(b))
-		switch {
-		case code >= 0:
-			n, err := io.ReadFull(br, buf[:code+1])
-			if err != nil {
-				return nil, err
-			}
-			dst = append(dst, buf[:n]...)
-		case code == -128:
-			// No-op.
-		default:
-			if b, err = br.ReadByte(); err != nil {
-				return nil, err
-			}
-			for j := 0; j < 1-code; j++ {
-				buf[j] = b
-			}
-			dst = append(dst, buf[:1-code]...)
-		}
-	}
-}
diff --git a/vendor/golang.org/x/image/tiff/consts.go b/vendor/golang.org/x/image/tiff/consts.go
deleted file mode 100644
index 3e5f7f14..00000000
--- a/vendor/golang.org/x/image/tiff/consts.go
+++ /dev/null
@@ -1,149 +0,0 @@
-// Copyright 2011 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package tiff
-
-// A tiff image file contains one or more images. The metadata
-// of each image is contained in an Image File Directory (IFD),
-// which contains entries of 12 bytes each and is described
-// on page 14-16 of the specification. An IFD entry consists of
-//
-//  - a tag, which describes the signification of the entry,
-//  - the data type and length of the entry,
-//  - the data itself or a pointer to it if it is more than 4 bytes.
-//
-// The presence of a length means that each IFD is effectively an array.
-
-const (
-	leHeader = "II\x2A\x00" // Header for little-endian files.
-	beHeader = "MM\x00\x2A" // Header for big-endian files.
-
-	ifdLen = 12 // Length of an IFD entry in bytes.
-)
-
-// Data types (p. 14-16 of the spec).
-const (
-	dtByte     = 1
-	dtASCII    = 2
-	dtShort    = 3
-	dtLong     = 4
-	dtRational = 5
-)
-
-// The length of one instance of each data type in bytes.
-var lengths = [...]uint32{0, 1, 1, 2, 4, 8}
-
-// Tags (see p. 28-41 of the spec).
-const (
-	tImageWidth                = 256
-	tImageLength               = 257
-	tBitsPerSample             = 258
-	tCompression               = 259
-	tPhotometricInterpretation = 262
-
-	tFillOrder = 266
-
-	tStripOffsets    = 273
-	tSamplesPerPixel = 277
-	tRowsPerStrip    = 278
-	tStripByteCounts = 279
-
-	tT4Options = 292 // CCITT Group 3 options, a set of 32 flag bits.
-	tT6Options = 293 // CCITT Group 4 options, a set of 32 flag bits.
-
-	tTileWidth      = 322
-	tTileLength     = 323
-	tTileOffsets    = 324
-	tTileByteCounts = 325
-
-	tXResolution    = 282
-	tYResolution    = 283
-	tResolutionUnit = 296
-
-	tPredictor    = 317
-	tColorMap     = 320
-	tExtraSamples = 338
-	tSampleFormat = 339
-)
-
-// Compression types (defined in various places in the spec and supplements).
-const (
-	cNone       = 1
-	cCCITT      = 2
-	cG3         = 3 // Group 3 Fax.
-	cG4         = 4 // Group 4 Fax.
-	cLZW        = 5
-	cJPEGOld    = 6 // Superseded by cJPEG.
-	cJPEG       = 7
-	cDeflate    = 8 // zlib compression.
-	cPackBits   = 32773
-	cDeflateOld = 32946 // Superseded by cDeflate.
-)
-
-// Photometric interpretation values (see p. 37 of the spec).
-const (
-	pWhiteIsZero = 0
-	pBlackIsZero = 1
-	pRGB         = 2
-	pPaletted    = 3
-	pTransMask   = 4 // transparency mask
-	pCMYK        = 5
-	pYCbCr       = 6
-	pCIELab      = 8
-)
-
-// Values for the tPredictor tag (page 64-65 of the spec).
-const (
-	prNone       = 1
-	prHorizontal = 2
-)
-
-// Values for the tResolutionUnit tag (page 18).
-const (
-	resNone    = 1
-	resPerInch = 2 // Dots per inch.
-	resPerCM   = 3 // Dots per centimeter.
-)
-
-// imageMode represents the mode of the image.
-type imageMode int
-
-const (
-	mBilevel imageMode = iota
-	mPaletted
-	mGray
-	mGrayInvert
-	mRGB
-	mRGBA
-	mNRGBA
-	mCMYK
-)
-
-// CompressionType describes the type of compression used in Options.
-type CompressionType int
-
-// Constants for supported compression types.
-const (
-	Uncompressed CompressionType = iota
-	Deflate
-	LZW
-	CCITTGroup3
-	CCITTGroup4
-)
-
-// specValue returns the compression type constant from the TIFF spec that
-// is equivalent to c.
-func (c CompressionType) specValue() uint32 {
-	switch c {
-	case LZW:
-		return cLZW
-	case Deflate:
-		return cDeflate
-	case CCITTGroup3:
-		return cG3
-	case CCITTGroup4:
-		return cG4
-	}
-	return cNone
-}
diff --git a/vendor/golang.org/x/image/tiff/fuzz.go b/vendor/golang.org/x/image/tiff/fuzz.go
deleted file mode 100644
index b27c5400..00000000
--- a/vendor/golang.org/x/image/tiff/fuzz.go
+++ /dev/null
@@ -1,30 +0,0 @@
-// Copyright 2019 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build gofuzz
-// +build gofuzz
-
-package tiff
-
-import "bytes"
-
-func Fuzz(data []byte) int {
-	cfg, err := DecodeConfig(bytes.NewReader(data))
-	if err != nil {
-		return 0
-	}
-	if cfg.Width*cfg.Height > 1e6 {
-		return 0
-	}
-	img, err := Decode(bytes.NewReader(data))
-	if err != nil {
-		return 0
-	}
-	var w bytes.Buffer
-	err = Encode(&w, img, nil)
-	if err != nil {
-		panic(err)
-	}
-	return 1
-}
diff --git a/vendor/golang.org/x/image/tiff/lzw/reader.go b/vendor/golang.org/x/image/tiff/lzw/reader.go
deleted file mode 100644
index 78204ba9..00000000
--- a/vendor/golang.org/x/image/tiff/lzw/reader.go
+++ /dev/null
@@ -1,272 +0,0 @@
-// Copyright 2011 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// Package lzw implements the Lempel-Ziv-Welch compressed data format,
-// described in T. A. Welch, ``A Technique for High-Performance Data
-// Compression'', Computer, 17(6) (June 1984), pp 8-19.
-//
-// In particular, it implements LZW as used by the TIFF file format, including
-// an "off by one" algorithmic difference when compared to standard LZW.
-package lzw // import "golang.org/x/image/tiff/lzw"
-
-/*
-This file was branched from src/pkg/compress/lzw/reader.go in the
-standard library. Differences from the original are marked with "NOTE".
-
-The tif_lzw.c file in the libtiff C library has this comment:
-
-----
-The 5.0 spec describes a different algorithm than Aldus
-implements.  Specifically, Aldus does code length transitions
-one code earlier than should be done (for real LZW).
-Earlier versions of this library implemented the correct
-LZW algorithm, but emitted codes in a bit order opposite
-to the TIFF spec.  Thus, to maintain compatibility w/ Aldus
-we interpret MSB-LSB ordered codes to be images written w/
-old versions of this library, but otherwise adhere to the
-Aldus "off by one" algorithm.
-----
-
-The Go code doesn't read (invalid) TIFF files written by old versions of
-libtiff, but the LZW algorithm in this package still differs from the one in
-Go's standard package library to accomodate this "off by one" in valid TIFFs.
-*/
-
-import (
-	"bufio"
-	"errors"
-	"fmt"
-	"io"
-)
-
-// Order specifies the bit ordering in an LZW data stream.
-type Order int
-
-const (
-	// LSB means Least Significant Bits first, as used in the GIF file format.
-	LSB Order = iota
-	// MSB means Most Significant Bits first, as used in the TIFF and PDF
-	// file formats.
-	MSB
-)
-
-const (
-	maxWidth           = 12
-	decoderInvalidCode = 0xffff
-	flushBuffer        = 1 << maxWidth
-)
-
-// decoder is the state from which the readXxx method converts a byte
-// stream into a code stream.
-type decoder struct {
-	r        io.ByteReader
-	bits     uint32
-	nBits    uint
-	width    uint
-	read     func(*decoder) (uint16, error) // readLSB or readMSB
-	litWidth int                            // width in bits of literal codes
-	err      error
-
-	// The first 1<<litWidth codes are literal codes.
-	// The next two codes mean clear and EOF.
-	// Other valid codes are in the range [lo, hi] where lo := clear + 2,
-	// with the upper bound incrementing on each code seen.
-	// overflow is the code at which hi overflows the code width. NOTE: TIFF's LZW is "off by one".
-	// last is the most recently seen code, or decoderInvalidCode.
-	clear, eof, hi, overflow, last uint16
-
-	// Each code c in [lo, hi] expands to two or more bytes. For c != hi:
-	//   suffix[c] is the last of these bytes.
-	//   prefix[c] is the code for all but the last byte.
-	//   This code can either be a literal code or another code in [lo, c).
-	// The c == hi case is a special case.
-	suffix [1 << maxWidth]uint8
-	prefix [1 << maxWidth]uint16
-
-	// output is the temporary output buffer.
-	// Literal codes are accumulated from the start of the buffer.
-	// Non-literal codes decode to a sequence of suffixes that are first
-	// written right-to-left from the end of the buffer before being copied
-	// to the start of the buffer.
-	// It is flushed when it contains >= 1<<maxWidth bytes,
-	// so that there is always room to decode an entire code.
-	output [2 * 1 << maxWidth]byte
-	o      int    // write index into output
-	toRead []byte // bytes to return from Read
-}
-
-// readLSB returns the next code for "Least Significant Bits first" data.
-func (d *decoder) readLSB() (uint16, error) {
-	for d.nBits < d.width {
-		x, err := d.r.ReadByte()
-		if err != nil {
-			return 0, err
-		}
-		d.bits |= uint32(x) << d.nBits
-		d.nBits += 8
-	}
-	code := uint16(d.bits & (1<<d.width - 1))
-	d.bits >>= d.width
-	d.nBits -= d.width
-	return code, nil
-}
-
-// readMSB returns the next code for "Most Significant Bits first" data.
-func (d *decoder) readMSB() (uint16, error) {
-	for d.nBits < d.width {
-		x, err := d.r.ReadByte()
-		if err != nil {
-			return 0, err
-		}
-		d.bits |= uint32(x) << (24 - d.nBits)
-		d.nBits += 8
-	}
-	code := uint16(d.bits >> (32 - d.width))
-	d.bits <<= d.width
-	d.nBits -= d.width
-	return code, nil
-}
-
-func (d *decoder) Read(b []byte) (int, error) {
-	for {
-		if len(d.toRead) > 0 {
-			n := copy(b, d.toRead)
-			d.toRead = d.toRead[n:]
-			return n, nil
-		}
-		if d.err != nil {
-			return 0, d.err
-		}
-		d.decode()
-	}
-}
-
-// decode decompresses bytes from r and leaves them in d.toRead.
-// read specifies how to decode bytes into codes.
-// litWidth is the width in bits of literal codes.
-func (d *decoder) decode() {
-	// Loop over the code stream, converting codes into decompressed bytes.
-loop:
-	for {
-		code, err := d.read(d)
-		if err != nil {
-			if err == io.EOF {
-				err = io.ErrUnexpectedEOF
-			}
-			d.err = err
-			break
-		}
-		switch {
-		case code < d.clear:
-			// We have a literal code.
-			d.output[d.o] = uint8(code)
-			d.o++
-			if d.last != decoderInvalidCode {
-				// Save what the hi code expands to.
-				d.suffix[d.hi] = uint8(code)
-				d.prefix[d.hi] = d.last
-			}
-		case code == d.clear:
-			d.width = 1 + uint(d.litWidth)
-			d.hi = d.eof
-			d.overflow = 1 << d.width
-			d.last = decoderInvalidCode
-			continue
-		case code == d.eof:
-			d.err = io.EOF
-			break loop
-		case code <= d.hi:
-			c, i := code, len(d.output)-1
-			if code == d.hi && d.last != decoderInvalidCode {
-				// code == hi is a special case which expands to the last expansion
-				// followed by the head of the last expansion. To find the head, we walk
-				// the prefix chain until we find a literal code.
-				c = d.last
-				for c >= d.clear {
-					c = d.prefix[c]
-				}
-				d.output[i] = uint8(c)
-				i--
-				c = d.last
-			}
-			// Copy the suffix chain into output and then write that to w.
-			for c >= d.clear {
-				d.output[i] = d.suffix[c]
-				i--
-				c = d.prefix[c]
-			}
-			d.output[i] = uint8(c)
-			d.o += copy(d.output[d.o:], d.output[i:])
-			if d.last != decoderInvalidCode {
-				// Save what the hi code expands to.
-				d.suffix[d.hi] = uint8(c)
-				d.prefix[d.hi] = d.last
-			}
-		default:
-			d.err = errors.New("lzw: invalid code")
-			break loop
-		}
-		d.last, d.hi = code, d.hi+1
-		if d.hi+1 >= d.overflow { // NOTE: the "+1" is where TIFF's LZW differs from the standard algorithm.
-			if d.width == maxWidth {
-				d.last = decoderInvalidCode
-			} else {
-				d.width++
-				d.overflow <<= 1
-			}
-		}
-		if d.o >= flushBuffer {
-			break
-		}
-	}
-	// Flush pending output.
-	d.toRead = d.output[:d.o]
-	d.o = 0
-}
-
-var errClosed = errors.New("lzw: reader/writer is closed")
-
-func (d *decoder) Close() error {
-	d.err = errClosed // in case any Reads come along
-	return nil
-}
-
-// NewReader creates a new io.ReadCloser.
-// Reads from the returned io.ReadCloser read and decompress data from r.
-// If r does not also implement io.ByteReader,
-// the decompressor may read more data than necessary from r.
-// It is the caller's responsibility to call Close on the ReadCloser when
-// finished reading.
-// The number of bits to use for literal codes, litWidth, must be in the
-// range [2,8] and is typically 8. It must equal the litWidth
-// used during compression.
-func NewReader(r io.Reader, order Order, litWidth int) io.ReadCloser {
-	d := new(decoder)
-	switch order {
-	case LSB:
-		d.read = (*decoder).readLSB
-	case MSB:
-		d.read = (*decoder).readMSB
-	default:
-		d.err = errors.New("lzw: unknown order")
-		return d
-	}
-	if litWidth < 2 || 8 < litWidth {
-		d.err = fmt.Errorf("lzw: litWidth %d out of range", litWidth)
-		return d
-	}
-	if br, ok := r.(io.ByteReader); ok {
-		d.r = br
-	} else {
-		d.r = bufio.NewReader(r)
-	}
-	d.litWidth = litWidth
-	d.width = 1 + uint(litWidth)
-	d.clear = uint16(1) << uint(litWidth)
-	d.eof, d.hi = d.clear+1, d.clear+1
-	d.overflow = uint16(1) << d.width
-	d.last = decoderInvalidCode
-
-	return d
-}
diff --git a/vendor/golang.org/x/image/tiff/reader.go b/vendor/golang.org/x/image/tiff/reader.go
deleted file mode 100644
index de73f4b9..00000000
--- a/vendor/golang.org/x/image/tiff/reader.go
+++ /dev/null
@@ -1,709 +0,0 @@
-// Copyright 2011 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// Package tiff implements a TIFF image decoder and encoder.
-//
-// The TIFF specification is at http://partners.adobe.com/public/developer/en/tiff/TIFF6.pdf
-package tiff // import "golang.org/x/image/tiff"
-
-import (
-	"compress/zlib"
-	"encoding/binary"
-	"fmt"
-	"image"
-	"image/color"
-	"io"
-	"io/ioutil"
-	"math"
-
-	"golang.org/x/image/ccitt"
-	"golang.org/x/image/tiff/lzw"
-)
-
-// A FormatError reports that the input is not a valid TIFF image.
-type FormatError string
-
-func (e FormatError) Error() string {
-	return "tiff: invalid format: " + string(e)
-}
-
-// An UnsupportedError reports that the input uses a valid but
-// unimplemented feature.
-type UnsupportedError string
-
-func (e UnsupportedError) Error() string {
-	return "tiff: unsupported feature: " + string(e)
-}
-
-var errNoPixels = FormatError("not enough pixel data")
-
-type decoder struct {
-	r         io.ReaderAt
-	byteOrder binary.ByteOrder
-	config    image.Config
-	mode      imageMode
-	bpp       uint
-	features  map[int][]uint
-	palette   []color.Color
-
-	buf   []byte
-	off   int    // Current offset in buf.
-	v     uint32 // Buffer value for reading with arbitrary bit depths.
-	nbits uint   // Remaining number of bits in v.
-}
-
-// firstVal returns the first uint of the features entry with the given tag,
-// or 0 if the tag does not exist.
-func (d *decoder) firstVal(tag int) uint {
-	f := d.features[tag]
-	if len(f) == 0 {
-		return 0
-	}
-	return f[0]
-}
-
-// ifdUint decodes the IFD entry in p, which must be of the Byte, Short
-// or Long type, and returns the decoded uint values.
-func (d *decoder) ifdUint(p []byte) (u []uint, err error) {
-	var raw []byte
-	if len(p) < ifdLen {
-		return nil, FormatError("bad IFD entry")
-	}
-
-	datatype := d.byteOrder.Uint16(p[2:4])
-	if dt := int(datatype); dt <= 0 || dt >= len(lengths) {
-		return nil, UnsupportedError("IFD entry datatype")
-	}
-
-	count := d.byteOrder.Uint32(p[4:8])
-	if count > math.MaxInt32/lengths[datatype] {
-		return nil, FormatError("IFD data too large")
-	}
-	if datalen := lengths[datatype] * count; datalen > 4 {
-		// The IFD contains a pointer to the real value.
-		raw = make([]byte, datalen)
-		_, err = d.r.ReadAt(raw, int64(d.byteOrder.Uint32(p[8:12])))
-	} else {
-		raw = p[8 : 8+datalen]
-	}
-	if err != nil {
-		return nil, err
-	}
-
-	u = make([]uint, count)
-	switch datatype {
-	case dtByte:
-		for i := uint32(0); i < count; i++ {
-			u[i] = uint(raw[i])
-		}
-	case dtShort:
-		for i := uint32(0); i < count; i++ {
-			u[i] = uint(d.byteOrder.Uint16(raw[2*i : 2*(i+1)]))
-		}
-	case dtLong:
-		for i := uint32(0); i < count; i++ {
-			u[i] = uint(d.byteOrder.Uint32(raw[4*i : 4*(i+1)]))
-		}
-	default:
-		return nil, UnsupportedError("data type")
-	}
-	return u, nil
-}
-
-// parseIFD decides whether the IFD entry in p is "interesting" and
-// stows away the data in the decoder. It returns the tag number of the
-// entry and an error, if any.
-func (d *decoder) parseIFD(p []byte) (int, error) {
-	tag := d.byteOrder.Uint16(p[0:2])
-	switch tag {
-	case tBitsPerSample,
-		tExtraSamples,
-		tPhotometricInterpretation,
-		tCompression,
-		tPredictor,
-		tStripOffsets,
-		tStripByteCounts,
-		tRowsPerStrip,
-		tTileWidth,
-		tTileLength,
-		tTileOffsets,
-		tTileByteCounts,
-		tImageLength,
-		tImageWidth,
-		tFillOrder,
-		tT4Options,
-		tT6Options:
-		val, err := d.ifdUint(p)
-		if err != nil {
-			return 0, err
-		}
-		d.features[int(tag)] = val
-	case tColorMap:
-		val, err := d.ifdUint(p)
-		if err != nil {
-			return 0, err
-		}
-		numcolors := len(val) / 3
-		if len(val)%3 != 0 || numcolors <= 0 || numcolors > 256 {
-			return 0, FormatError("bad ColorMap length")
-		}
-		d.palette = make([]color.Color, numcolors)
-		for i := 0; i < numcolors; i++ {
-			d.palette[i] = color.RGBA64{
-				uint16(val[i]),
-				uint16(val[i+numcolors]),
-				uint16(val[i+2*numcolors]),
-				0xffff,
-			}
-		}
-	case tSampleFormat:
-		// Page 27 of the spec: If the SampleFormat is present and
-		// the value is not 1 [= unsigned integer data], a Baseline
-		// TIFF reader that cannot handle the SampleFormat value
-		// must terminate the import process gracefully.
-		val, err := d.ifdUint(p)
-		if err != nil {
-			return 0, err
-		}
-		for _, v := range val {
-			if v != 1 {
-				return 0, UnsupportedError("sample format")
-			}
-		}
-	}
-	return int(tag), nil
-}
-
-// readBits reads n bits from the internal buffer starting at the current offset.
-func (d *decoder) readBits(n uint) (v uint32, ok bool) {
-	for d.nbits < n {
-		d.v <<= 8
-		if d.off >= len(d.buf) {
-			return 0, false
-		}
-		d.v |= uint32(d.buf[d.off])
-		d.off++
-		d.nbits += 8
-	}
-	d.nbits -= n
-	rv := d.v >> d.nbits
-	d.v &^= rv << d.nbits
-	return rv, true
-}
-
-// flushBits discards the unread bits in the buffer used by readBits.
-// It is used at the end of a line.
-func (d *decoder) flushBits() {
-	d.v = 0
-	d.nbits = 0
-}
-
-// minInt returns the smaller of x or y.
-func minInt(a, b int) int {
-	if a <= b {
-		return a
-	}
-	return b
-}
-
-// decode decodes the raw data of an image.
-// It reads from d.buf and writes the strip or tile into dst.
-func (d *decoder) decode(dst image.Image, xmin, ymin, xmax, ymax int) error {
-	d.off = 0
-
-	// Apply horizontal predictor if necessary.
-	// In this case, p contains the color difference to the preceding pixel.
-	// See page 64-65 of the spec.
-	if d.firstVal(tPredictor) == prHorizontal {
-		switch d.bpp {
-		case 16:
-			var off int
-			n := 2 * len(d.features[tBitsPerSample]) // bytes per sample times samples per pixel
-			for y := ymin; y < ymax; y++ {
-				off += n
-				for x := 0; x < (xmax-xmin-1)*n; x += 2 {
-					if off+2 > len(d.buf) {
-						return errNoPixels
-					}
-					v0 := d.byteOrder.Uint16(d.buf[off-n : off-n+2])
-					v1 := d.byteOrder.Uint16(d.buf[off : off+2])
-					d.byteOrder.PutUint16(d.buf[off:off+2], v1+v0)
-					off += 2
-				}
-			}
-		case 8:
-			var off int
-			n := 1 * len(d.features[tBitsPerSample]) // bytes per sample times samples per pixel
-			for y := ymin; y < ymax; y++ {
-				off += n
-				for x := 0; x < (xmax-xmin-1)*n; x++ {
-					if off >= len(d.buf) {
-						return errNoPixels
-					}
-					d.buf[off] += d.buf[off-n]
-					off++
-				}
-			}
-		case 1:
-			return UnsupportedError("horizontal predictor with 1 BitsPerSample")
-		}
-	}
-
-	rMaxX := minInt(xmax, dst.Bounds().Max.X)
-	rMaxY := minInt(ymax, dst.Bounds().Max.Y)
-	switch d.mode {
-	case mGray, mGrayInvert:
-		if d.bpp == 16 {
-			img := dst.(*image.Gray16)
-			for y := ymin; y < rMaxY; y++ {
-				for x := xmin; x < rMaxX; x++ {
-					if d.off+2 > len(d.buf) {
-						return errNoPixels
-					}
-					v := d.byteOrder.Uint16(d.buf[d.off : d.off+2])
-					d.off += 2
-					if d.mode == mGrayInvert {
-						v = 0xffff - v
-					}
-					img.SetGray16(x, y, color.Gray16{v})
-				}
-				if rMaxX == img.Bounds().Max.X {
-					d.off += 2 * (xmax - img.Bounds().Max.X)
-				}
-			}
-		} else {
-			img := dst.(*image.Gray)
-			max := uint32((1 << d.bpp) - 1)
-			for y := ymin; y < rMaxY; y++ {
-				for x := xmin; x < rMaxX; x++ {
-					v, ok := d.readBits(d.bpp)
-					if !ok {
-						return errNoPixels
-					}
-					v = v * 0xff / max
-					if d.mode == mGrayInvert {
-						v = 0xff - v
-					}
-					img.SetGray(x, y, color.Gray{uint8(v)})
-				}
-				d.flushBits()
-			}
-		}
-	case mPaletted:
-		img := dst.(*image.Paletted)
-		for y := ymin; y < rMaxY; y++ {
-			for x := xmin; x < rMaxX; x++ {
-				v, ok := d.readBits(d.bpp)
-				if !ok {
-					return errNoPixels
-				}
-				img.SetColorIndex(x, y, uint8(v))
-			}
-			d.flushBits()
-		}
-	case mRGB:
-		if d.bpp == 16 {
-			img := dst.(*image.RGBA64)
-			for y := ymin; y < rMaxY; y++ {
-				for x := xmin; x < rMaxX; x++ {
-					if d.off+6 > len(d.buf) {
-						return errNoPixels
-					}
-					r := d.byteOrder.Uint16(d.buf[d.off+0 : d.off+2])
-					g := d.byteOrder.Uint16(d.buf[d.off+2 : d.off+4])
-					b := d.byteOrder.Uint16(d.buf[d.off+4 : d.off+6])
-					d.off += 6
-					img.SetRGBA64(x, y, color.RGBA64{r, g, b, 0xffff})
-				}
-			}
-		} else {
-			img := dst.(*image.RGBA)
-			for y := ymin; y < rMaxY; y++ {
-				min := img.PixOffset(xmin, y)
-				max := img.PixOffset(rMaxX, y)
-				off := (y - ymin) * (xmax - xmin) * 3
-				for i := min; i < max; i += 4 {
-					if off+3 > len(d.buf) {
-						return errNoPixels
-					}
-					img.Pix[i+0] = d.buf[off+0]
-					img.Pix[i+1] = d.buf[off+1]
-					img.Pix[i+2] = d.buf[off+2]
-					img.Pix[i+3] = 0xff
-					off += 3
-				}
-			}
-		}
-	case mNRGBA:
-		if d.bpp == 16 {
-			img := dst.(*image.NRGBA64)
-			for y := ymin; y < rMaxY; y++ {
-				for x := xmin; x < rMaxX; x++ {
-					if d.off+8 > len(d.buf) {
-						return errNoPixels
-					}
-					r := d.byteOrder.Uint16(d.buf[d.off+0 : d.off+2])
-					g := d.byteOrder.Uint16(d.buf[d.off+2 : d.off+4])
-					b := d.byteOrder.Uint16(d.buf[d.off+4 : d.off+6])
-					a := d.byteOrder.Uint16(d.buf[d.off+6 : d.off+8])
-					d.off += 8
-					img.SetNRGBA64(x, y, color.NRGBA64{r, g, b, a})
-				}
-			}
-		} else {
-			img := dst.(*image.NRGBA)
-			for y := ymin; y < rMaxY; y++ {
-				min := img.PixOffset(xmin, y)
-				max := img.PixOffset(rMaxX, y)
-				i0, i1 := (y-ymin)*(xmax-xmin)*4, (y-ymin+1)*(xmax-xmin)*4
-				if i1 > len(d.buf) {
-					return errNoPixels
-				}
-				copy(img.Pix[min:max], d.buf[i0:i1])
-			}
-		}
-	case mRGBA:
-		if d.bpp == 16 {
-			img := dst.(*image.RGBA64)
-			for y := ymin; y < rMaxY; y++ {
-				for x := xmin; x < rMaxX; x++ {
-					if d.off+8 > len(d.buf) {
-						return errNoPixels
-					}
-					r := d.byteOrder.Uint16(d.buf[d.off+0 : d.off+2])
-					g := d.byteOrder.Uint16(d.buf[d.off+2 : d.off+4])
-					b := d.byteOrder.Uint16(d.buf[d.off+4 : d.off+6])
-					a := d.byteOrder.Uint16(d.buf[d.off+6 : d.off+8])
-					d.off += 8
-					img.SetRGBA64(x, y, color.RGBA64{r, g, b, a})
-				}
-			}
-		} else {
-			img := dst.(*image.RGBA)
-			for y := ymin; y < rMaxY; y++ {
-				min := img.PixOffset(xmin, y)
-				max := img.PixOffset(rMaxX, y)
-				i0, i1 := (y-ymin)*(xmax-xmin)*4, (y-ymin+1)*(xmax-xmin)*4
-				if i1 > len(d.buf) {
-					return errNoPixels
-				}
-				copy(img.Pix[min:max], d.buf[i0:i1])
-			}
-		}
-	}
-
-	return nil
-}
-
-func newDecoder(r io.Reader) (*decoder, error) {
-	d := &decoder{
-		r:        newReaderAt(r),
-		features: make(map[int][]uint),
-	}
-
-	p := make([]byte, 8)
-	if _, err := d.r.ReadAt(p, 0); err != nil {
-		if err == io.EOF {
-			err = io.ErrUnexpectedEOF
-		}
-		return nil, err
-	}
-	switch string(p[0:4]) {
-	case leHeader:
-		d.byteOrder = binary.LittleEndian
-	case beHeader:
-		d.byteOrder = binary.BigEndian
-	default:
-		return nil, FormatError("malformed header")
-	}
-
-	ifdOffset := int64(d.byteOrder.Uint32(p[4:8]))
-
-	// The first two bytes contain the number of entries (12 bytes each).
-	if _, err := d.r.ReadAt(p[0:2], ifdOffset); err != nil {
-		return nil, err
-	}
-	numItems := int(d.byteOrder.Uint16(p[0:2]))
-
-	// All IFD entries are read in one chunk.
-	p = make([]byte, ifdLen*numItems)
-	if _, err := d.r.ReadAt(p, ifdOffset+2); err != nil {
-		return nil, err
-	}
-
-	prevTag := -1
-	for i := 0; i < len(p); i += ifdLen {
-		tag, err := d.parseIFD(p[i : i+ifdLen])
-		if err != nil {
-			return nil, err
-		}
-		if tag <= prevTag {
-			return nil, FormatError("tags are not sorted in ascending order")
-		}
-		prevTag = tag
-	}
-
-	d.config.Width = int(d.firstVal(tImageWidth))
-	d.config.Height = int(d.firstVal(tImageLength))
-
-	if _, ok := d.features[tBitsPerSample]; !ok {
-		// Default is 1 per specification.
-		d.features[tBitsPerSample] = []uint{1}
-	}
-	d.bpp = d.firstVal(tBitsPerSample)
-	switch d.bpp {
-	case 0:
-		return nil, FormatError("BitsPerSample must not be 0")
-	case 1, 8, 16:
-		// Nothing to do, these are accepted by this implementation.
-	default:
-		return nil, UnsupportedError(fmt.Sprintf("BitsPerSample of %v", d.bpp))
-	}
-
-	// Determine the image mode.
-	switch d.firstVal(tPhotometricInterpretation) {
-	case pRGB:
-		if d.bpp == 16 {
-			for _, b := range d.features[tBitsPerSample] {
-				if b != 16 {
-					return nil, FormatError("wrong number of samples for 16bit RGB")
-				}
-			}
-		} else {
-			for _, b := range d.features[tBitsPerSample] {
-				if b != 8 {
-					return nil, FormatError("wrong number of samples for 8bit RGB")
-				}
-			}
-		}
-		// RGB images normally have 3 samples per pixel.
-		// If there are more, ExtraSamples (p. 31-32 of the spec)
-		// gives their meaning (usually an alpha channel).
-		//
-		// This implementation does not support extra samples
-		// of an unspecified type.
-		switch len(d.features[tBitsPerSample]) {
-		case 3:
-			d.mode = mRGB
-			if d.bpp == 16 {
-				d.config.ColorModel = color.RGBA64Model
-			} else {
-				d.config.ColorModel = color.RGBAModel
-			}
-		case 4:
-			switch d.firstVal(tExtraSamples) {
-			case 1:
-				d.mode = mRGBA
-				if d.bpp == 16 {
-					d.config.ColorModel = color.RGBA64Model
-				} else {
-					d.config.ColorModel = color.RGBAModel
-				}
-			case 2:
-				d.mode = mNRGBA
-				if d.bpp == 16 {
-					d.config.ColorModel = color.NRGBA64Model
-				} else {
-					d.config.ColorModel = color.NRGBAModel
-				}
-			default:
-				return nil, FormatError("wrong number of samples for RGB")
-			}
-		default:
-			return nil, FormatError("wrong number of samples for RGB")
-		}
-	case pPaletted:
-		d.mode = mPaletted
-		d.config.ColorModel = color.Palette(d.palette)
-	case pWhiteIsZero:
-		d.mode = mGrayInvert
-		if d.bpp == 16 {
-			d.config.ColorModel = color.Gray16Model
-		} else {
-			d.config.ColorModel = color.GrayModel
-		}
-	case pBlackIsZero:
-		d.mode = mGray
-		if d.bpp == 16 {
-			d.config.ColorModel = color.Gray16Model
-		} else {
-			d.config.ColorModel = color.GrayModel
-		}
-	default:
-		return nil, UnsupportedError("color model")
-	}
-
-	return d, nil
-}
-
-// DecodeConfig returns the color model and dimensions of a TIFF image without
-// decoding the entire image.
-func DecodeConfig(r io.Reader) (image.Config, error) {
-	d, err := newDecoder(r)
-	if err != nil {
-		return image.Config{}, err
-	}
-	return d.config, nil
-}
-
-func ccittFillOrder(tiffFillOrder uint) ccitt.Order {
-	if tiffFillOrder == 2 {
-		return ccitt.LSB
-	}
-	return ccitt.MSB
-}
-
-// Decode reads a TIFF image from r and returns it as an image.Image.
-// The type of Image returned depends on the contents of the TIFF.
-func Decode(r io.Reader) (img image.Image, err error) {
-	d, err := newDecoder(r)
-	if err != nil {
-		return
-	}
-
-	blockPadding := false
-	blockWidth := d.config.Width
-	blockHeight := d.config.Height
-	blocksAcross := 1
-	blocksDown := 1
-
-	if d.config.Width == 0 {
-		blocksAcross = 0
-	}
-	if d.config.Height == 0 {
-		blocksDown = 0
-	}
-
-	var blockOffsets, blockCounts []uint
-
-	if int(d.firstVal(tTileWidth)) != 0 {
-		blockPadding = true
-
-		blockWidth = int(d.firstVal(tTileWidth))
-		blockHeight = int(d.firstVal(tTileLength))
-
-		if blockWidth != 0 {
-			blocksAcross = (d.config.Width + blockWidth - 1) / blockWidth
-		}
-		if blockHeight != 0 {
-			blocksDown = (d.config.Height + blockHeight - 1) / blockHeight
-		}
-
-		blockCounts = d.features[tTileByteCounts]
-		blockOffsets = d.features[tTileOffsets]
-
-	} else {
-		if int(d.firstVal(tRowsPerStrip)) != 0 {
-			blockHeight = int(d.firstVal(tRowsPerStrip))
-		}
-
-		if blockHeight != 0 {
-			blocksDown = (d.config.Height + blockHeight - 1) / blockHeight
-		}
-
-		blockOffsets = d.features[tStripOffsets]
-		blockCounts = d.features[tStripByteCounts]
-	}
-
-	// Check if we have the right number of strips/tiles, offsets and counts.
-	if n := blocksAcross * blocksDown; len(blockOffsets) < n || len(blockCounts) < n {
-		return nil, FormatError("inconsistent header")
-	}
-
-	imgRect := image.Rect(0, 0, d.config.Width, d.config.Height)
-	switch d.mode {
-	case mGray, mGrayInvert:
-		if d.bpp == 16 {
-			img = image.NewGray16(imgRect)
-		} else {
-			img = image.NewGray(imgRect)
-		}
-	case mPaletted:
-		img = image.NewPaletted(imgRect, d.palette)
-	case mNRGBA:
-		if d.bpp == 16 {
-			img = image.NewNRGBA64(imgRect)
-		} else {
-			img = image.NewNRGBA(imgRect)
-		}
-	case mRGB, mRGBA:
-		if d.bpp == 16 {
-			img = image.NewRGBA64(imgRect)
-		} else {
-			img = image.NewRGBA(imgRect)
-		}
-	}
-
-	for i := 0; i < blocksAcross; i++ {
-		blkW := blockWidth
-		if !blockPadding && i == blocksAcross-1 && d.config.Width%blockWidth != 0 {
-			blkW = d.config.Width % blockWidth
-		}
-		for j := 0; j < blocksDown; j++ {
-			blkH := blockHeight
-			if !blockPadding && j == blocksDown-1 && d.config.Height%blockHeight != 0 {
-				blkH = d.config.Height % blockHeight
-			}
-			offset := int64(blockOffsets[j*blocksAcross+i])
-			n := int64(blockCounts[j*blocksAcross+i])
-			switch d.firstVal(tCompression) {
-
-			// According to the spec, Compression does not have a default value,
-			// but some tools interpret a missing Compression value as none so we do
-			// the same.
-			case cNone, 0:
-				if b, ok := d.r.(*buffer); ok {
-					d.buf, err = b.Slice(int(offset), int(n))
-				} else {
-					d.buf = make([]byte, n)
-					_, err = d.r.ReadAt(d.buf, offset)
-				}
-			case cG3:
-				inv := d.firstVal(tPhotometricInterpretation) == pWhiteIsZero
-				order := ccittFillOrder(d.firstVal(tFillOrder))
-				r := ccitt.NewReader(io.NewSectionReader(d.r, offset, n), order, ccitt.Group3, blkW, blkH, &ccitt.Options{Invert: inv, Align: false})
-				d.buf, err = ioutil.ReadAll(r)
-			case cG4:
-				inv := d.firstVal(tPhotometricInterpretation) == pWhiteIsZero
-				order := ccittFillOrder(d.firstVal(tFillOrder))
-				r := ccitt.NewReader(io.NewSectionReader(d.r, offset, n), order, ccitt.Group4, blkW, blkH, &ccitt.Options{Invert: inv, Align: false})
-				d.buf, err = ioutil.ReadAll(r)
-			case cLZW:
-				r := lzw.NewReader(io.NewSectionReader(d.r, offset, n), lzw.MSB, 8)
-				d.buf, err = ioutil.ReadAll(r)
-				r.Close()
-			case cDeflate, cDeflateOld:
-				var r io.ReadCloser
-				r, err = zlib.NewReader(io.NewSectionReader(d.r, offset, n))
-				if err != nil {
-					return nil, err
-				}
-				d.buf, err = ioutil.ReadAll(r)
-				r.Close()
-			case cPackBits:
-				d.buf, err = unpackBits(io.NewSectionReader(d.r, offset, n))
-			default:
-				err = UnsupportedError(fmt.Sprintf("compression value %d", d.firstVal(tCompression)))
-			}
-			if err != nil {
-				return nil, err
-			}
-
-			xmin := i * blockWidth
-			ymin := j * blockHeight
-			xmax := xmin + blkW
-			ymax := ymin + blkH
-			err = d.decode(img, xmin, ymin, xmax, ymax)
-			if err != nil {
-				return nil, err
-			}
-		}
-	}
-	return
-}
-
-func init() {
-	image.RegisterFormat("tiff", leHeader, Decode, DecodeConfig)
-	image.RegisterFormat("tiff", beHeader, Decode, DecodeConfig)
-}
diff --git a/vendor/golang.org/x/image/tiff/writer.go b/vendor/golang.org/x/image/tiff/writer.go
deleted file mode 100644
index c8a01cea..00000000
--- a/vendor/golang.org/x/image/tiff/writer.go
+++ /dev/null
@@ -1,438 +0,0 @@
-// Copyright 2012 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package tiff
-
-import (
-	"bytes"
-	"compress/zlib"
-	"encoding/binary"
-	"image"
-	"io"
-	"sort"
-)
-
-// The TIFF format allows to choose the order of the different elements freely.
-// The basic structure of a TIFF file written by this package is:
-//
-//   1. Header (8 bytes).
-//   2. Image data.
-//   3. Image File Directory (IFD).
-//   4. "Pointer area" for larger entries in the IFD.
-
-// We only write little-endian TIFF files.
-var enc = binary.LittleEndian
-
-// An ifdEntry is a single entry in an Image File Directory.
-// A value of type dtRational is composed of two 32-bit values,
-// thus data contains two uints (numerator and denominator) for a single number.
-type ifdEntry struct {
-	tag      int
-	datatype int
-	data     []uint32
-}
-
-func (e ifdEntry) putData(p []byte) {
-	for _, d := range e.data {
-		switch e.datatype {
-		case dtByte, dtASCII:
-			p[0] = byte(d)
-			p = p[1:]
-		case dtShort:
-			enc.PutUint16(p, uint16(d))
-			p = p[2:]
-		case dtLong, dtRational:
-			enc.PutUint32(p, uint32(d))
-			p = p[4:]
-		}
-	}
-}
-
-type byTag []ifdEntry
-
-func (d byTag) Len() int           { return len(d) }
-func (d byTag) Less(i, j int) bool { return d[i].tag < d[j].tag }
-func (d byTag) Swap(i, j int)      { d[i], d[j] = d[j], d[i] }
-
-func encodeGray(w io.Writer, pix []uint8, dx, dy, stride int, predictor bool) error {
-	if !predictor {
-		return writePix(w, pix, dy, dx, stride)
-	}
-	buf := make([]byte, dx)
-	for y := 0; y < dy; y++ {
-		min := y*stride + 0
-		max := y*stride + dx
-		off := 0
-		var v0 uint8
-		for i := min; i < max; i++ {
-			v1 := pix[i]
-			buf[off] = v1 - v0
-			v0 = v1
-			off++
-		}
-		if _, err := w.Write(buf); err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-func encodeGray16(w io.Writer, pix []uint8, dx, dy, stride int, predictor bool) error {
-	buf := make([]byte, dx*2)
-	for y := 0; y < dy; y++ {
-		min := y*stride + 0
-		max := y*stride + dx*2
-		off := 0
-		var v0 uint16
-		for i := min; i < max; i += 2 {
-			// An image.Gray16's Pix is in big-endian order.
-			v1 := uint16(pix[i])<<8 | uint16(pix[i+1])
-			if predictor {
-				v0, v1 = v1, v1-v0
-			}
-			// We only write little-endian TIFF files.
-			buf[off+0] = byte(v1)
-			buf[off+1] = byte(v1 >> 8)
-			off += 2
-		}
-		if _, err := w.Write(buf); err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-func encodeRGBA(w io.Writer, pix []uint8, dx, dy, stride int, predictor bool) error {
-	if !predictor {
-		return writePix(w, pix, dy, dx*4, stride)
-	}
-	buf := make([]byte, dx*4)
-	for y := 0; y < dy; y++ {
-		min := y*stride + 0
-		max := y*stride + dx*4
-		off := 0
-		var r0, g0, b0, a0 uint8
-		for i := min; i < max; i += 4 {
-			r1, g1, b1, a1 := pix[i+0], pix[i+1], pix[i+2], pix[i+3]
-			buf[off+0] = r1 - r0
-			buf[off+1] = g1 - g0
-			buf[off+2] = b1 - b0
-			buf[off+3] = a1 - a0
-			off += 4
-			r0, g0, b0, a0 = r1, g1, b1, a1
-		}
-		if _, err := w.Write(buf); err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-func encodeRGBA64(w io.Writer, pix []uint8, dx, dy, stride int, predictor bool) error {
-	buf := make([]byte, dx*8)
-	for y := 0; y < dy; y++ {
-		min := y*stride + 0
-		max := y*stride + dx*8
-		off := 0
-		var r0, g0, b0, a0 uint16
-		for i := min; i < max; i += 8 {
-			// An image.RGBA64's Pix is in big-endian order.
-			r1 := uint16(pix[i+0])<<8 | uint16(pix[i+1])
-			g1 := uint16(pix[i+2])<<8 | uint16(pix[i+3])
-			b1 := uint16(pix[i+4])<<8 | uint16(pix[i+5])
-			a1 := uint16(pix[i+6])<<8 | uint16(pix[i+7])
-			if predictor {
-				r0, r1 = r1, r1-r0
-				g0, g1 = g1, g1-g0
-				b0, b1 = b1, b1-b0
-				a0, a1 = a1, a1-a0
-			}
-			// We only write little-endian TIFF files.
-			buf[off+0] = byte(r1)
-			buf[off+1] = byte(r1 >> 8)
-			buf[off+2] = byte(g1)
-			buf[off+3] = byte(g1 >> 8)
-			buf[off+4] = byte(b1)
-			buf[off+5] = byte(b1 >> 8)
-			buf[off+6] = byte(a1)
-			buf[off+7] = byte(a1 >> 8)
-			off += 8
-		}
-		if _, err := w.Write(buf); err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-func encode(w io.Writer, m image.Image, predictor bool) error {
-	bounds := m.Bounds()
-	buf := make([]byte, 4*bounds.Dx())
-	for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
-		off := 0
-		if predictor {
-			var r0, g0, b0, a0 uint8
-			for x := bounds.Min.X; x < bounds.Max.X; x++ {
-				r, g, b, a := m.At(x, y).RGBA()
-				r1 := uint8(r >> 8)
-				g1 := uint8(g >> 8)
-				b1 := uint8(b >> 8)
-				a1 := uint8(a >> 8)
-				buf[off+0] = r1 - r0
-				buf[off+1] = g1 - g0
-				buf[off+2] = b1 - b0
-				buf[off+3] = a1 - a0
-				off += 4
-				r0, g0, b0, a0 = r1, g1, b1, a1
-			}
-		} else {
-			for x := bounds.Min.X; x < bounds.Max.X; x++ {
-				r, g, b, a := m.At(x, y).RGBA()
-				buf[off+0] = uint8(r >> 8)
-				buf[off+1] = uint8(g >> 8)
-				buf[off+2] = uint8(b >> 8)
-				buf[off+3] = uint8(a >> 8)
-				off += 4
-			}
-		}
-		if _, err := w.Write(buf); err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-// writePix writes the internal byte array of an image to w. It is less general
-// but much faster then encode. writePix is used when pix directly
-// corresponds to one of the TIFF image types.
-func writePix(w io.Writer, pix []byte, nrows, length, stride int) error {
-	if length == stride {
-		_, err := w.Write(pix[:nrows*length])
-		return err
-	}
-	for ; nrows > 0; nrows-- {
-		if _, err := w.Write(pix[:length]); err != nil {
-			return err
-		}
-		pix = pix[stride:]
-	}
-	return nil
-}
-
-func writeIFD(w io.Writer, ifdOffset int, d []ifdEntry) error {
-	var buf [ifdLen]byte
-	// Make space for "pointer area" containing IFD entry data
-	// longer than 4 bytes.
-	parea := make([]byte, 1024)
-	pstart := ifdOffset + ifdLen*len(d) + 6
-	var o int // Current offset in parea.
-
-	// The IFD has to be written with the tags in ascending order.
-	sort.Sort(byTag(d))
-
-	// Write the number of entries in this IFD.
-	if err := binary.Write(w, enc, uint16(len(d))); err != nil {
-		return err
-	}
-	for _, ent := range d {
-		enc.PutUint16(buf[0:2], uint16(ent.tag))
-		enc.PutUint16(buf[2:4], uint16(ent.datatype))
-		count := uint32(len(ent.data))
-		if ent.datatype == dtRational {
-			count /= 2
-		}
-		enc.PutUint32(buf[4:8], count)
-		datalen := int(count * lengths[ent.datatype])
-		if datalen <= 4 {
-			ent.putData(buf[8:12])
-		} else {
-			if (o + datalen) > len(parea) {
-				newlen := len(parea) + 1024
-				for (o + datalen) > newlen {
-					newlen += 1024
-				}
-				newarea := make([]byte, newlen)
-				copy(newarea, parea)
-				parea = newarea
-			}
-			ent.putData(parea[o : o+datalen])
-			enc.PutUint32(buf[8:12], uint32(pstart+o))
-			o += datalen
-		}
-		if _, err := w.Write(buf[:]); err != nil {
-			return err
-		}
-	}
-	// The IFD ends with the offset of the next IFD in the file,
-	// or zero if it is the last one (page 14).
-	if err := binary.Write(w, enc, uint32(0)); err != nil {
-		return err
-	}
-	_, err := w.Write(parea[:o])
-	return err
-}
-
-// Options are the encoding parameters.
-type Options struct {
-	// Compression is the type of compression used.
-	Compression CompressionType
-	// Predictor determines whether a differencing predictor is used;
-	// if true, instead of each pixel's color, the color difference to the
-	// preceding one is saved.  This improves the compression for certain
-	// types of images and compressors. For example, it works well for
-	// photos with Deflate compression.
-	Predictor bool
-}
-
-// Encode writes the image m to w. opt determines the options used for
-// encoding, such as the compression type. If opt is nil, an uncompressed
-// image is written.
-func Encode(w io.Writer, m image.Image, opt *Options) error {
-	d := m.Bounds().Size()
-
-	compression := uint32(cNone)
-	predictor := false
-	if opt != nil {
-		compression = opt.Compression.specValue()
-		// The predictor field is only used with LZW. See page 64 of the spec.
-		predictor = opt.Predictor && compression == cLZW
-	}
-
-	_, err := io.WriteString(w, leHeader)
-	if err != nil {
-		return err
-	}
-
-	// Compressed data is written into a buffer first, so that we
-	// know the compressed size.
-	var buf bytes.Buffer
-	// dst holds the destination for the pixel data of the image --
-	// either w or a writer to buf.
-	var dst io.Writer
-	// imageLen is the length of the pixel data in bytes.
-	// The offset of the IFD is imageLen + 8 header bytes.
-	var imageLen int
-
-	switch compression {
-	case cNone:
-		dst = w
-		// Write IFD offset before outputting pixel data.
-		switch m.(type) {
-		case *image.Paletted:
-			imageLen = d.X * d.Y * 1
-		case *image.Gray:
-			imageLen = d.X * d.Y * 1
-		case *image.Gray16:
-			imageLen = d.X * d.Y * 2
-		case *image.RGBA64:
-			imageLen = d.X * d.Y * 8
-		case *image.NRGBA64:
-			imageLen = d.X * d.Y * 8
-		default:
-			imageLen = d.X * d.Y * 4
-		}
-		err = binary.Write(w, enc, uint32(imageLen+8))
-		if err != nil {
-			return err
-		}
-	case cDeflate:
-		dst = zlib.NewWriter(&buf)
-	}
-
-	pr := uint32(prNone)
-	photometricInterpretation := uint32(pRGB)
-	samplesPerPixel := uint32(4)
-	bitsPerSample := []uint32{8, 8, 8, 8}
-	extraSamples := uint32(0)
-	colorMap := []uint32{}
-
-	if predictor {
-		pr = prHorizontal
-	}
-	switch m := m.(type) {
-	case *image.Paletted:
-		photometricInterpretation = pPaletted
-		samplesPerPixel = 1
-		bitsPerSample = []uint32{8}
-		colorMap = make([]uint32, 256*3)
-		for i := 0; i < 256 && i < len(m.Palette); i++ {
-			r, g, b, _ := m.Palette[i].RGBA()
-			colorMap[i+0*256] = uint32(r)
-			colorMap[i+1*256] = uint32(g)
-			colorMap[i+2*256] = uint32(b)
-		}
-		err = encodeGray(dst, m.Pix, d.X, d.Y, m.Stride, predictor)
-	case *image.Gray:
-		photometricInterpretation = pBlackIsZero
-		samplesPerPixel = 1
-		bitsPerSample = []uint32{8}
-		err = encodeGray(dst, m.Pix, d.X, d.Y, m.Stride, predictor)
-	case *image.Gray16:
-		photometricInterpretation = pBlackIsZero
-		samplesPerPixel = 1
-		bitsPerSample = []uint32{16}
-		err = encodeGray16(dst, m.Pix, d.X, d.Y, m.Stride, predictor)
-	case *image.NRGBA:
-		extraSamples = 2 // Unassociated alpha.
-		err = encodeRGBA(dst, m.Pix, d.X, d.Y, m.Stride, predictor)
-	case *image.NRGBA64:
-		extraSamples = 2 // Unassociated alpha.
-		bitsPerSample = []uint32{16, 16, 16, 16}
-		err = encodeRGBA64(dst, m.Pix, d.X, d.Y, m.Stride, predictor)
-	case *image.RGBA:
-		extraSamples = 1 // Associated alpha.
-		err = encodeRGBA(dst, m.Pix, d.X, d.Y, m.Stride, predictor)
-	case *image.RGBA64:
-		extraSamples = 1 // Associated alpha.
-		bitsPerSample = []uint32{16, 16, 16, 16}
-		err = encodeRGBA64(dst, m.Pix, d.X, d.Y, m.Stride, predictor)
-	default:
-		extraSamples = 1 // Associated alpha.
-		err = encode(dst, m, predictor)
-	}
-	if err != nil {
-		return err
-	}
-
-	if compression != cNone {
-		if err = dst.(io.Closer).Close(); err != nil {
-			return err
-		}
-		imageLen = buf.Len()
-		if err = binary.Write(w, enc, uint32(imageLen+8)); err != nil {
-			return err
-		}
-		if _, err = buf.WriteTo(w); err != nil {
-			return err
-		}
-	}
-
-	ifd := []ifdEntry{
-		{tImageWidth, dtShort, []uint32{uint32(d.X)}},
-		{tImageLength, dtShort, []uint32{uint32(d.Y)}},
-		{tBitsPerSample, dtShort, bitsPerSample},
-		{tCompression, dtShort, []uint32{compression}},
-		{tPhotometricInterpretation, dtShort, []uint32{photometricInterpretation}},
-		{tStripOffsets, dtLong, []uint32{8}},
-		{tSamplesPerPixel, dtShort, []uint32{samplesPerPixel}},
-		{tRowsPerStrip, dtShort, []uint32{uint32(d.Y)}},
-		{tStripByteCounts, dtLong, []uint32{uint32(imageLen)}},
-		// There is currently no support for storing the image
-		// resolution, so give a bogus value of 72x72 dpi.
-		{tXResolution, dtRational, []uint32{72, 1}},
-		{tYResolution, dtRational, []uint32{72, 1}},
-		{tResolutionUnit, dtShort, []uint32{resPerInch}},
-	}
-	if pr != prNone {
-		ifd = append(ifd, ifdEntry{tPredictor, dtShort, []uint32{pr}})
-	}
-	if len(colorMap) != 0 {
-		ifd = append(ifd, ifdEntry{tColorMap, dtShort, colorMap})
-	}
-	if extraSamples > 0 {
-		ifd = append(ifd, ifdEntry{tExtraSamples, dtShort, []uint32{extraSamples}})
-	}
-
-	return writeIFD(w, imageLen+8, ifd)
-}