diff --git a/kadai1/imura81gt/.devcontainer/Dockerfile b/kadai1/imura81gt/.devcontainer/Dockerfile
new file mode 100644
index 0000000..12623de
--- /dev/null
+++ b/kadai1/imura81gt/.devcontainer/Dockerfile
@@ -0,0 +1,68 @@
+#-------------------------------------------------------------------------------------------------------------
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License. See https://go.microsoft.com/fwlink/?linkid=2090316 for license information.
+#-------------------------------------------------------------------------------------------------------------
+
+FROM golang:1
+
+# Avoid warnings by switching to noninteractive
+ENV DEBIAN_FRONTEND=noninteractive
+
+# This Dockerfile adds a non-root 'vscode' user with sudo access. However, for Linux,
+# this user's GID/UID must match your local user UID/GID to avoid permission issues
+# with bind mounts. Update USER_UID / USER_GID if yours is not 1000. See
+# https://aka.ms/vscode-remote/containers/non-root-user for details.
+ARG USERNAME=vscode
+ARG USER_UID=1000
+ARG USER_GID=$USER_UID
+
+# Configure apt, install packages and tools
+RUN apt-get update \
+    && apt-get -y install --no-install-recommends apt-utils dialog 2>&1 \
+    #
+    # Verify git, process tools, lsb-release (common in install instructions for CLIs) installed
+    && apt-get -y install git iproute2 procps lsb-release \
+    #
+    # Install gocode-gomod
+    && go get -x -d github.com/stamblerre/gocode 2>&1 \
+    && go build -o gocode-gomod github.com/stamblerre/gocode \
+    && mv gocode-gomod $GOPATH/bin/ \
+    #
+    # Install Go tools
+    && go get -u -v \
+        github.com/mdempsky/gocode \
+        github.com/uudashr/gopkgs/cmd/gopkgs \
+        github.com/ramya-rao-a/go-outline \
+        github.com/acroca/go-symbols \
+        github.com/godoctor/godoctor \
+        golang.org/x/tools/cmd/guru \
+        golang.org/x/tools/cmd/gorename \
+        github.com/rogpeppe/godef \
+        github.com/zmb3/gogetdoc \
+        github.com/haya14busa/goplay/cmd/goplay \
+        github.com/sqs/goreturns \
+        github.com/josharian/impl \
+        github.com/davidrjenni/reftools/cmd/fillstruct \
+        github.com/fatih/gomodifytags \
+        github.com/cweill/gotests/... \
+        golang.org/x/tools/cmd/goimports \
+        golang.org/x/lint/golint \
+        golang.org/x/tools/cmd/gopls \
+        github.com/alecthomas/gometalinter \
+        honnef.co/go/tools/... \
+        github.com/golangci/golangci-lint/cmd/golangci-lint \
+        github.com/mgechev/revive \
+        github.com/derekparker/delve/cmd/dlv 2>&1 \
+    #
+    # Create a non-root user to use if preferred - see https://aka.ms/vscode-remote/containers/non-root-user.
+    && groupadd --gid $USER_GID $USERNAME \
+    && useradd -s /bin/bash --uid $USER_UID --gid $USER_GID -m $USERNAME \
+    # [Optional] Add sudo support
+    && apt-get install -y sudo \
+    && echo $USERNAME ALL=\(root\) NOPASSWD:ALL > /etc/sudoers.d/$USERNAME \
+    && chmod 0440 /etc/sudoers.d/$USERNAME \
+    #
+    # Clean up
+    && apt-get autoremove -y \
+    && apt-get clean -y \
+    && rm -rf /var/lib/apt/lists/*
\ No newline at end of file
diff --git a/kadai1/imura81gt/.devcontainer/devcontainer.json b/kadai1/imura81gt/.devcontainer/devcontainer.json
new file mode 100644
index 0000000..e9e5f3e
--- /dev/null
+++ b/kadai1/imura81gt/.devcontainer/devcontainer.json
@@ -0,0 +1,32 @@
+// For format details, see https://aka.ms/vscode-remote/devcontainer.json or the definition README at
+// https://github.com/microsoft/vscode-dev-containers/tree/master/containers/go
+{
+	"name": "Go",
+	"dockerFile": "Dockerfile",
+	"runArgs": [
+		// Uncomment the next line to use a non-root user. On Linux, this will prevent
+		// new files getting created as root, but you may need to update the USER_UID
+		// and USER_GID in .devcontainer/Dockerfile to match your user if not 1000.
+		// "-u", "vscode",
+
+		"--cap-add=SYS_PTRACE", "--security-opt", "seccomp=unconfined"
+	],
+
+	// Use 'settings' to set *default* container specific settings.json values on container create. 
+	// You can edit these settings after create using File > Preferences > Settings > Remote.
+	"settings": { 
+		"terminal.integrated.shell.linux": "/bin/bash",
+		"go.gopath": "/go"
+	},
+	
+	// Uncomment the next line if you want to publish any ports.
+	// "appPort": [],
+
+	// Uncomment the next line to run commands after the container is created.
+	// "postCreateCommand": "go version",
+
+	// Add the IDs of extensions you want installed when the container is created in the array below.
+	"extensions": [
+		"ms-vscode.go"
+	]
+}
\ No newline at end of file
diff --git a/kadai1/imura81gt/README.md b/kadai1/imura81gt/README.md
new file mode 100644
index 0000000..cc5e8d0
--- /dev/null
+++ b/kadai1/imura81gt/README.md
@@ -0,0 +1,183 @@
+Convert Image
+================================================================================
+
+TOC
+--------------------------------------------------------------------------------
+- [Convert Image](#convert-image)
+  - [TOC](#toc)
+  - [Q. 【TRY】画像変換コマンドを作ろう](#q-try画像変換コマンドを作ろう)
+  - [Links](#links)
+    - [About filepath](#about-filepath)
+    - [About image](#about-image)
+  - [Build](#build)
+  - [Usage](#usage)
+  - [Test Data](#test-data)
+  - [Example](#example)
+    - [e.g. use no option](#eg-use-no-option)
+    - [e.g. use option](#eg-use-option)
+
+Q. 【TRY】画像変換コマンドを作ろう
+--------------------------------------------------------------------------------
+
+次の仕様を満たすコマンドを作って下さい
+
+- [x] 1. ディレクトリを指定する
+- [x] 2. 指定したディレクトリ以下のJPGファイルをPNGに変換（デフォルト）
+- [x] 3. ディレクトリ以下は再帰的に処理する
+- [x] 4. 変換前と変換後の画像形式を指定できる（オプション）
+
+以下を満たすように開発してください
+
+- [x] 5. mainパッケージと分離する
+- [x] 6. 自作パッケージと標準パッケージと準標準パッケージのみ使う
+  - 準標準パッケージ：golang.org/x以下のパッケージ
+- [x] 8. ユーザ定義型を作ってみる
+- [x] 9. GoDocを生成してみる
+
+
+Links
+--------------------------------------------------------------------------------
+
+### About filepath
+
+- https://golang.org/pkg/path/filepath/
+
+### About image
+
+- [Package image](https://golang.org/pkg/image/)
+    - [gif](https://golang.org/pkg/image/gif/)
+    - [jpeg](https://golang.org/pkg/image/jpeg/)
+    - [png](https://golang.org/pkg/image/png/)
+    - get format
+        - [DecodeConfig](https://golang.org/pkg/image/#DecodeConfig)
+- [The Go Blog](https://blog.golang.org/)
+    - [The Go image package](https://blog.golang.org/go-image-package#TOC_5.)
+
+
+Go doc
+--------------------------------------------------------------------------------
+
+```
+$ go doc github.com/gopherdojo/dojo7/kadai1/imura81gt/imgconv/img
+package img // import "github.com/gopherdojo/dojo7/kadai1/imura81gt/imgconv/img"
+
+func AllImageFiles(dirs []string) (files []string)
+func Convert(r io.Reader, w io.Writer, t string) error
+func ConvertAll(dirs []string, iType ImageType, oType ImageType) error
+func ExpectedImageFiles(files []string, iType ImageType) (f []string)
+func IsExpectedImage(path string, iType ImageType) bool
+func IsImage(path string) bool
+type ImageType struct{ ... }
+```
+
+OR
+
+```
+cd $(go env GOPATH)/src/github.com/gopherdojo/dojo7/kadai1/imura81gt/imgconv
+godoc -http=:8080
+```
+
+http://localhost:8080/pkg/github.com/gopherdojo/dojo7/kadai1/imura81gt/imgconv/img/
+
+Build
+--------------------------------------------------------------------------------
+
+```
+cd $(go env GOPATH)/src/github.com/gopherdojo/dojo7/kadai1/imura81gt/imgconv
+GO111MODULE=on go build
+```
+
+Usage
+--------------------------------------------------------------------------------
+
+```
+$ ./imgconv
+./imgconv <option> dir1 dir2 dir3
+option:
+  -G    convert to gif.
+  -J    convert to jpeg.
+  -P    convert to png.
+  -g    inpt files are gif.
+  -j    inpt files are jpeg.
+  -p    inpt files are png.
+```
+
+
+Test Data
+--------------------------------------------------------------------------------
+
+```
+$ tree testdata/
+testdata/
+├── chdir
+│   ├── gLenna.gif
+│   ├── jLenna.jpeg
+│   └── pLenna.png
+├── gLenna.gif
+├── jLenna.jpg
+├── pLenna.png
+├── this_is_not_image.gif
+├── this_is_not_image.jpg
+└── this_is_not_image.png
+
+1 directory, 9 files
+$
+```
+
+
+Example
+--------------------------------------------------------------------------------
+
+### e.g. use no option
+
+```
+$ ./imgconv testdata/
+```
+
+In stdout, the command output input files and output files.
+
+```
+["testdata/chdir/jLenna.jpeg" "testdata/jLenna.jpg"]
+["output/png/testdata/chdir/jLenna.png" "output/png/testdata/jLenna.png"]
+```
+
+```
+$ tree output/
+output/
+└── png
+    └── testdata
+        ├── chdir
+        │   └── jLenna.png
+        └── jLenna.png
+$
+```
+
+### e.g. use option
+
+- input: png, jpeg
+- output: gif
+
+```
+$ ./imgconv testdata/ -p -j -G
+```
+
+In stdout, the command output input files and output files.
+
+```
+
+["testdata/chdir/jLenna.jpeg" "testdata/chdir/pLenna.png" "testdata/jLenna.jpg" "testdata/pLenna.png"]
+["output/gif/testdata/chdir/jLenna.gif" "output/gif/testdata/chdir/pLenna.gif" "output/gif/testdata/jLenna.gif" "output/gif/testdata/pLenna.gif"]
+```
+
+```
+$ tree output/
+output/
+└── gif
+    └── testdata
+        ├── chdir
+        │   ├── jLenna.gif
+        │   └── pLenna.gif
+        ├── jLenna.gif
+        └── pLenna.gif
+$
+```
diff --git a/kadai1/imura81gt/imgconv/.gitignore b/kadai1/imura81gt/imgconv/.gitignore
new file mode 100644
index 0000000..171d55f
--- /dev/null
+++ b/kadai1/imura81gt/imgconv/.gitignore
@@ -0,0 +1,2 @@
+output
+imgconv
diff --git a/kadai1/imura81gt/imgconv/go.mod b/kadai1/imura81gt/imgconv/go.mod
new file mode 100644
index 0000000..f2983a6
--- /dev/null
+++ b/kadai1/imura81gt/imgconv/go.mod
@@ -0,0 +1,3 @@
+module github.com/gopherdojo/dojo7/kadai1/imura81gt/imgconv
+
+go 1.12
diff --git a/kadai1/imura81gt/imgconv/go.sum b/kadai1/imura81gt/imgconv/go.sum
new file mode 100644
index 0000000..5726ce0
--- /dev/null
+++ b/kadai1/imura81gt/imgconv/go.sum
@@ -0,0 +1 @@
+github.com/gopherdojo/dojo7 v0.0.0-20190903074013-69385d40c994 h1:UbdhtSFDdFiSYOb/TkEmlRIUFQRrBlKOzVDY3+SXaSw=
diff --git a/kadai1/imura81gt/imgconv/img/convert.go b/kadai1/imura81gt/imgconv/img/convert.go
new file mode 100644
index 0000000..4c812e8
--- /dev/null
+++ b/kadai1/imura81gt/imgconv/img/convert.go
@@ -0,0 +1,195 @@
+package img
+
+import (
+	"fmt"
+	"image"
+	"image/gif"
+	"image/jpeg"
+	"image/png"
+	"io"
+	"os"
+	"path/filepath"
+)
+
+const (
+	saveDir  = "output"
+	pngType  = "png"
+	jpegType = "jpeg"
+	gifType  = "gif"
+)
+
+// ConvType is type of converted image files
+// 8. ユーザ定義型を作ってみる
+type ImageType struct {
+	Png  bool
+	Jpeg bool
+	Gif  bool
+}
+
+func (i ImageType) Enable() []string {
+	var types []string
+	if i.Png {
+		types = append(types, pngType)
+	}
+	if i.Jpeg {
+		types = append(types, jpegType)
+	}
+	if i.Gif {
+		types = append(types, gifType)
+	}
+	return types
+}
+
+// ConvertAll convert all image files in dirs
+func ConvertAll(dirs []string, iType ImageType, oType ImageType) error {
+	files, err := AllImageFiles(dirs)
+	if err != nil {
+		return err
+	}
+	files = ExpectedImageFiles(files, iType)
+	fmt.Printf("%q\n", files)
+
+	var oFiles []string
+	for _, iPath := range files {
+		for _, t := range oType.Enable() {
+			oPath := filepath.Join(saveDir, t, iPath[:len(iPath)-len(filepath.Ext(iPath))]+"."+t)
+
+			i, err := os.Open(iPath)
+			if err != nil {
+				fmt.Fprintln(os.Stderr, err)
+				return err
+			}
+
+			err = os.MkdirAll(filepath.Dir(oPath), 0755)
+			if err != nil {
+				fmt.Fprintln(os.Stderr, err)
+				return err
+			}
+
+			w, err := os.Create(oPath)
+			defer func() error {
+				err = w.Close()
+				if err != nil {
+					return err
+				}
+				return nil
+			}()
+			if err != nil {
+				fmt.Fprintln(os.Stderr, err)
+				return err
+			}
+
+			err = Convert(i, w, t)
+			if err != nil {
+				fmt.Fprintln(os.Stderr, err)
+				return err
+			}
+			oFiles = append(oFiles, oPath)
+		}
+	}
+	fmt.Printf("%q\n", oFiles)
+	return nil
+}
+
+func AllImageFiles(dirs []string) ([]string, error) {
+	// 3. ディレクトリ以下は再帰的に処理する
+	var files []string
+	for _, dir := range dirs {
+		err := filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
+			if info.IsDir() {
+				return nil
+			}
+
+			if IsImage(path) {
+				files = append(files, path)
+			}
+
+			return nil
+		})
+		if err != nil {
+			fmt.Fprintln(os.Stderr, err)
+			return nil, err
+		}
+	}
+	return files, nil
+}
+
+func ExpectedImageFiles(files []string, iType ImageType) (f []string) {
+	var ret []string
+	for _, path := range files {
+		if IsExpectedImage(path, iType) {
+			ret = append(ret, path)
+		}
+	}
+	return ret
+}
+
+// IsImage return true if path is image.
+func IsImage(path string) bool {
+	r, err := os.Open(path)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		return false
+	}
+	defer r.Close()
+
+	_, _, err = image.DecodeConfig(r)
+	if err != nil {
+		return false
+	}
+	return true
+}
+
+func IsExpectedImage(path string, iType ImageType) bool {
+	r, err := os.Open(path)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		return false
+	}
+	defer r.Close()
+
+	_, format, err := image.DecodeConfig(r)
+	if err != nil {
+		return false
+	}
+
+	for _, t := range iType.Enable() {
+		if t == format {
+			return true
+		}
+	}
+
+	return false
+}
+
+// Convert function is image file converter
+func Convert(r io.Reader, w io.Writer, t string) error {
+	jpego := &jpeg.Options{
+		Quality: jpeg.DefaultQuality,
+	}
+
+	gifo := &gif.Options{
+		NumColors: 256,
+		Quantizer: nil,
+		Drawer:    nil,
+	}
+
+	m, _, err := image.Decode(r)
+	if err != nil {
+		return err
+	}
+
+	switch t {
+	case "png":
+		return png.Encode(w, m)
+	case "gif":
+		return gif.Encode(w, m, gifo)
+	case "jpeg", "jpg":
+		return jpeg.Encode(w, m, jpego)
+	default:
+		return png.Encode(w, m)
+	}
+
+	return nil
+
+}
diff --git a/kadai1/imura81gt/imgconv/main.go b/kadai1/imura81gt/imgconv/main.go
new file mode 100644
index 0000000..84fd552
--- /dev/null
+++ b/kadai1/imura81gt/imgconv/main.go
@@ -0,0 +1,80 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+
+	"github.com/gopherdojo/dojo7/kadai1/imura81gt/imgconv/img"
+)
+
+var (
+	dirs  []string
+	oType img.ImageType
+	iType img.ImageType
+)
+
+func main() {
+
+	// check that dir is existed.
+	for _, dir := range dirs {
+		_, err := os.Stat(dir)
+		if err != nil {
+			fmt.Fprintln(os.Stderr, err)
+			os.Exit(1)
+		}
+	}
+
+	err := img.ConvertAll(dirs, iType, oType)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+
+}
+
+func init() {
+	// 4. 変換前と変換後の画像形式を指定できる（オプション）
+	ip := flag.Bool("p", false, "inpt files are png.")
+	ij := flag.Bool("j", false, "inpt files are jpeg.")
+	ig := flag.Bool("g", false, "inpt files are gif.")
+
+	op := flag.Bool("P", false, "convert to png.")
+	oj := flag.Bool("J", false, "convert to jpeg.")
+	og := flag.Bool("G", false, "convert to gif.")
+
+	flag.Parse()
+
+	// 1. ディレクトリを指定する
+	dirs = flag.Args()
+
+	// 2. 指定したディレクトリ以下のJPGファイルをPNGに変換（デフォルト）
+	if !(*ip || *ij || *ig) {
+		*ij = true
+	}
+
+	if !(*op || *oj || *og) {
+		*op = true
+	}
+
+	// fmt.Println(*p, *j, *g)
+	oType = img.ImageType{
+		Png:  *op,
+		Jpeg: *oj,
+		Gif:  *og,
+	}
+
+	iType = img.ImageType{
+		Png:  *ip,
+		Jpeg: *ij,
+		Gif:  *ig,
+	}
+
+	if len(dirs) <= 0 {
+		fmt.Fprintf(os.Stderr, "%s <option> dir1 dir2 dir3\n", os.Args[0])
+		fmt.Fprintln(os.Stderr, "option:")
+		flag.PrintDefaults()
+		os.Exit(1)
+	}
+
+}
diff --git a/kadai1/imura81gt/imgconv/main_test.go b/kadai1/imura81gt/imgconv/main_test.go
new file mode 100644
index 0000000..06ab7d0
--- /dev/null
+++ b/kadai1/imura81gt/imgconv/main_test.go
@@ -0,0 +1 @@
+package main
diff --git a/kadai1/imura81gt/imgconv/testdata/chdir/gLenna.gif b/kadai1/imura81gt/imgconv/testdata/chdir/gLenna.gif
new file mode 100644
index 0000000..486a545
Binary files /dev/null and b/kadai1/imura81gt/imgconv/testdata/chdir/gLenna.gif differ
diff --git a/kadai1/imura81gt/imgconv/testdata/chdir/jLenna.jpeg b/kadai1/imura81gt/imgconv/testdata/chdir/jLenna.jpeg
new file mode 100644
index 0000000..b6dfc2a
Binary files /dev/null and b/kadai1/imura81gt/imgconv/testdata/chdir/jLenna.jpeg differ
diff --git a/kadai1/imura81gt/imgconv/testdata/chdir/pLenna.png b/kadai1/imura81gt/imgconv/testdata/chdir/pLenna.png
new file mode 100644
index 0000000..654a743
Binary files /dev/null and b/kadai1/imura81gt/imgconv/testdata/chdir/pLenna.png differ
diff --git a/kadai1/imura81gt/imgconv/testdata/gLenna.gif b/kadai1/imura81gt/imgconv/testdata/gLenna.gif
new file mode 100644
index 0000000..486a545
Binary files /dev/null and b/kadai1/imura81gt/imgconv/testdata/gLenna.gif differ
diff --git a/kadai1/imura81gt/imgconv/testdata/jLenna.jpg b/kadai1/imura81gt/imgconv/testdata/jLenna.jpg
new file mode 100644
index 0000000..201a025
Binary files /dev/null and b/kadai1/imura81gt/imgconv/testdata/jLenna.jpg differ
diff --git a/kadai1/imura81gt/imgconv/testdata/pLenna.png b/kadai1/imura81gt/imgconv/testdata/pLenna.png
new file mode 100644
index 0000000..59ef68a
Binary files /dev/null and b/kadai1/imura81gt/imgconv/testdata/pLenna.png differ
diff --git a/kadai1/imura81gt/imgconv/testdata/this_is_not_image.gif b/kadai1/imura81gt/imgconv/testdata/this_is_not_image.gif
new file mode 100644
index 0000000..e69de29
diff --git a/kadai1/imura81gt/imgconv/testdata/this_is_not_image.jpg b/kadai1/imura81gt/imgconv/testdata/this_is_not_image.jpg
new file mode 100644
index 0000000..e69de29
diff --git a/kadai1/imura81gt/imgconv/testdata/this_is_not_image.png b/kadai1/imura81gt/imgconv/testdata/this_is_not_image.png
new file mode 100644
index 0000000..e69de29