OpenCV/Patch to support WebP format on OpenCV 2.4.2

OpenCV/Patch to support WebP format on OpenCV 2.4.2 †

#multilang(ja){{

概要

OpenCV 2.4.2でWebP形式のフォーマットを扱えるようにするパッチです．
※OpenCV 2.4.2を対象としたパッチです．

ダウンロード

変更履歴

使い方

WebPライブラリのビルド

1. こちらからWebPのソースをダウンロードする．※今回はlibwebp-0.2.0.tar.gzを用いた．
2. libwebp-0.2.0.tar.gzを展開する．
3. Visual Studio コマンド プロンプトを起動する．
4. コマンド プロンプトでlibwebp-0.2.0のディレクトリに移動する．
5. 下記のコマンドを実行する（release用ライブラリが生成される）．

   nmake /f Makefile.vc CFG=release-static RTLIBCFG=static OBJDIR=output
   

   　※Linux，Macの場合は以下のコマンドを実行する．

   make -f makefile.unix

OpenCV WebPパッチの適用

1. 上記リンクからopencv2.4.2_webp_enable_patch_20120809.zipをダウンロードして展開します．
2. 展開したディレクトリをOpenCVディレクトリに上書きします． 　※Linux，Macに適用する場合には，パッチ（下記ファイル）の改行コードをあらかじめnkfコマンド等でLFに変換して下さい．

• opencv2.4.2_webp_enable_patch_20120809\CMakeLists?.txt
• opencv2.4.2_webp_enable_patch_20120809\cmake\OpenCVFindLibsGrfmt?.cmake
• opencv2.4.2_webp_enable_patch_20120809\cmake\OpenCVFindWebP.cmake
• opencv2.4.2_webp_enable_patch_20120809\modules\highgui\CMakeLists?.txt
• opencv2.4.2_webp_enable_patch_20120809\modules\highgui\include\opencv2\highgui\highgui.hpp
• opencv2.4.2_webp_enable_patch_20120809\modules\highgui\include\opencv2\highgui\highgui_c.h
• opencv2.4.2_webp_enable_patch_20120809\modules\highgui\src\grfmt_webp.cpp
• opencv2.4.2_webp_enable_patch_20120809\modules\highgui\src\grfmt_webp.hpp
• opencv2.4.2_webp_enable_patch_20120809\modules\highgui\src\grfmts.hpp
• opencv2.4.2_webp_enable_patch_20120809\modules\highgui\src\loadsave.cpp

OpenCVのビルド †

OpenCVをCMakeを用いてビルドする．

1. WITH_WEBPにチェックを入れて，「Configure」ボタンを押す．
   
   
   
   
2. WEBP_INCLUDE_DIRSにWebPのソースがあるディレクトリを指定して，「Generate」ボタンを押す．
   
   
   
   

おまけ(1)

下記のような設定をすることでデコード時のquality(0～100)を指定できる．
※以下の例では最大品質の100を指定．

C API

int param[2];
param[0] = CV_IMWRITE_WEBP_QUALITY;
param[1] = 100;
cvSaveImage("img.webp", img, &param[0]);

C++ API

vector<int> param = vector<int>(2);
param[0] = CV_IMWRITE_WEBP_QUALITY;
param[1] = 100;
imwrite("img.webp", img, param);

おまけ(2)

下記のような設定をすることでlossless圧縮を指定できる．

C API

int param[2];
param[0] = CV_IMWRITE_WEBP_LOSSLESS;
param[1] = 1;
cvSaveImage("img.webp", img, &param[0]);

C++ API

vector<int> param = vector<int>(2);
param[0] = CV_IMWRITE_WEBP_LOSSLESS;
param[1] = 1;
imwrite("img.webp", img, param);

制限事項

• Windows 32bit/Mac 64bitのみで動作検証．
• 保存対象画像となるdepthは8Uのみ．

注意点

• CV_IMWRITE_WEBP_QUALITYによる指定が無い場合，デフォルトで95が指定される．

}}

#multilang(en){{

Abstract

This page describes the method to use WebP format on OpenCV 2.4.2.

Download

ChangeLog?

Usage

Build WebP library

1. Please download WebP source code from Official page. I used libwebp-0.2.0.tar.gz for testing.
2. Please extract libwebp-0.2.0.tar.gz.
3. Please start Visual Studio command prompt.
4. Please move to libwebp-0.2.0 directory.
5. Please run the following command to make WebP library(release build).

   nmake /f Makefile.vc CFG=release-static RTLIBCFG=static OBJDIR=output

   　If you use on Linux or Max, please run the following command to make WebP library

   make -f makefile.unix

Applying WebP patch

1. Please download opencv2.4.2_webp_enable_patch_20120809.zip. And,extract this file.
2. Please overwrite to OpenCV's directory.

If you want to apply this patch to OpenCV-2.4.2(Linux or Mac), please convert newline character of these file to LF from CRLF.

• opencv2.4.2_webp_enable_patch_20120809\CMakeLists?.txt
• opencv2.4.2_webp_enable_patch_20120809\cmake\OpenCVFindLibsGrfmt?.cmake
• opencv2.4.2_webp_enable_patch_20120809\cmake\OpenCVFindWebP.cmake
• opencv2.4.2_webp_enable_patch_20120809\modules\highgui\CMakeLists?.txt
• opencv2.4.2_webp_enable_patch_20120809\modules\highgui\include\opencv2\highgui\highgui.hpp
• opencv2.4.2_webp_enable_patch_20120809\modules\highgui\include\opencv2\highgui\highgui_c.h
• opencv2.4.2_webp_enable_patch_20120809\modules\highgui\src\grfmt_webp.cpp
• opencv2.4.2_webp_enable_patch_20120809\modules\highgui\src\grfmt_webp.hpp
• opencv2.4.2_webp_enable_patch_20120809\modules\highgui\src\grfmts.hpp
• opencv2.4.2_webp_enable_patch_20120809\modules\highgui\src\loadsave.cpp

Build OpenCV

Please build OpenCV using CMake.

1. Please check WITH_WEBP and push Configure button.
   
   
   
   
2. Please specify WebP source's directory to WEBP_INCLUDE_DIRS and push Generate button.
   
   
   
   

Tips(1)

You can specify the compression quality(min:0, max:100) by the following settings.

C API

int param[2];
param[0] = CV_IMWRITE_WEBP_QUALITY;
param[1] = 100;
cvSaveImage("img.webp", img, &param[0]);

C++ API

vector<int> param = vector<int>(2);
param[0] = CV_IMWRITE_WEBP_QUALITY;
param[1] = 100;
imwrite("img.webp", img, param);

Tips(2)

You can specify the lossless compression by the following settings.

C API

int param[2];
param[0] = CV_IMWRITE_WEBP_LOSSLESS;
param[1] = 1;
cvSaveImage("img.webp", img, &param[0]);

C++ API

vector<int> param = vector<int>(2);
param[0] = CV_IMWRITE_WEBP_LOSSLESS;
param[1] = 1;
imwrite("img.webp", img, param);

Limitation

• I have only tested this environment.
  • Windows 32bit and Mac 64bit
• Save image depth supports 8U only.

Notes

• If you does not specify the quality by CV_IMWRITE_WEBP_QUALITY, 95 is specified by default. }}