如何在 Linux 中优化和压缩 JPEG 或 PNG 图片

information technologylinux

您是否想在将图片上传到云端或本地存储之前，优化或压缩图片而不损失其原始质量?有很多图形界面或网页应用程序可以帮助您优化图片。本文将指导您如何在 Linux 命令行中优化和压缩 JPEG 或 PNG 图片。

使用 jpegoptim

jpegoptim 是一个简单的实用程序，可以优化 JPEG 图片而不损失质量。它提供无损优化和"有损"优化，具体取决于设置，并具有最大质量因子。

要安装 jpegoptim，请使用以下命令:

$ sudo apt-get install jpegoptim

示例输出应如下所示 -

The following packages were automatically installed and are no longer required:
gcc-4.8-base:i386 libasn1-8-heimdal:i386 libasound2:i386
libasound2-plugins:i386 libasyncns0:i386 libavahi-client3:i386
libavahi-common-data:i386 libavahi-common3:i386 libbit-vector-perl
libcapi20-3:i386 libcarp-clan-perl libclass-method-modifiers-perl
libcups2:i386 libdata-random-perl libdate-calc-perl libdate-calc-xs-perl
libdrm-amdgpu1:i386 libdrm-intel1:i386 libdrm-nouveau2:i386
libdrm-radeon1:i386 libedit2:i386 libelf1:i386 libexif12:i386 libexpat1:i386
libffi6:i386 libflac8:i386 libfontconfig1:i386 libfreetype6:i386
libgcrypt11:i386 libgd-perl libgd3:i386 libgif4:i386
libgl1-mesa-dri-lts-wily:i386 libgl1-mesa-glx-lts-wily:i386
libglapi-mesa-lts-wily:i386 libglib2.0-0:i386 libglu1-mesa:i386
libgnome2-gconf-perl libgnutls26:i386 libgpg-error0:i386 libgphoto2-6:i386
libgphoto2-port10:i386 libgssapi-krb5-2:i386 libgssapi3-heimdal:i386
libgstreamer-plugins-base0.10-0:i386 libgstreamer0.10-0:i386
libhcrypto4-heimdal:i386 libheimbase1-heimdal:i386 libheimntlm0-heimdal:i386
libhx509-5-heimdal:i386 libice6:i386 libieee1284-3:i386
libjack-jackd2-0:i386 libjbig0:i386 libjpeg-turbo8:i386 libjpeg8:i386
libk5crypto3:i386 libkeyutils1:i386 libkrb5-26-heimdal:i386 libkrb5-3:i386
libkrb5support0:i386 liblcms2-2:i386 libldap-2.4-2:i386 libllvm3.6:i386
libltdl7:i386 libmouse-perl libmpg123-0:i386 libnet-dropbox-api-perl
libogg0:i386 libopenal1:i386 liborc-0.4-0:i386 libosmesa6:i386
libp11-kit-gnome-keyring:i386 libp11-kit0:i386 libpciaccess0:i386
libpulse0:i386 libroken18-heimdal:i386 libsamplerate0:i386 libsane:i386
libsasl2-2:i386 libsasl2-modules:i386 libsasl2-modules-db:i386 libsm6:i386
libsndfile1:i386 libspeexdsp1:i386 libsqlite3-0:i386 libssl1.0.0:i386
libstdc++6:i386 libtasn1-6:i386 libtiff5:i386 libtxc-dxtn-s2tc0:i386
.........................

使用 Jpegoptim 图像优化器

使用以下命令优化 tp1.jpg 文件

$ jpegoptim /home/linux/Desktop/tp1.jpg

示例输出应如下所示 -

/home/linux/Desktop/tp1.jpg 1024x744 24bit N IPTC Adobe JFIF [OK] 535222 --> 508663 bytes (4.96%), optimized.

上述命令将图像优化到最大可能大小，并减少 4.96% 的文件大小。但是，您可以将给定的图像压缩到特定大小，但这会禁用无损优化。

例如，要将上述图像压缩到大约 250K，请使用以下命令:

$ jpegoptim --size=250k /home/linux/Desktop/tp1.jpg

示例输出应如下所示 -

/home/linux/Desktop/tp1.jpg 1024x744 24bit N IPTC JFIF [OK] 508663 --> 249866 bytes (50.88%), optimized.

要查找文件大小，请使用以下命令-

$ du -sh /home/linux/Desktop/tp1.jpg

示例输出应如下所示 -

248K/home/linux/Desktop/tp1.jpg

jpegoptim 命令会将图像压缩到 248k 的大小。如有需要，您可以更改图像大小。

批量 JPEG 图像压缩和优化

jpegoptim 可以批量压缩图像，现在选择要压缩的图像文件夹，如下所示-

$ cd /home/linux/Desktop/img
/Desktop/img$ ls -l

上述命令会显示所有图像的列表，如下所示 -

total 2188
-rw-rw-r-- 1 linux linux 32616 Feb 27 10:46 Converted_file_1a46a9ef.jpg
-rw-rw-r-- 1 linux linux 35925 Feb 27 10:46 Converted_file_96eba41d.jpg
-rw-rw-r-- 1 linux linux 50600 Feb 27 10:46 Converted_file_dd3307c9.jpg
-rw-rw-r-- 1 linux linux 5083 Feb 27 10:48 LOGO122.png
-rw-rw-r-- 1 linux linux 2047570 Feb 27 12:39 nexus_6_0134.jpg
-rw-rw-r-- 1 linux linux 36364 Feb 27 10:45 unnamed.jpg

然后，您可以运行以下命令一次性压缩所有JPEG图像。

/Desktop/img$ jpegoptim --size=250k *.jpg

示例输出应如下所示 -

Converted_file_1a46a9ef.jpg 480x800 24bit N JFIF [OK] 32616 --> 32616 bytes (0.00%), skipped.
Converted_file_96eba41d.jpg 480x800 24bit N JFIF [OK] 35925 --> 35925 bytes (0.00%), skipped.
Converted_file_dd3307c9.jpg 480x800 24bit N JFIF [OK] 50600 --> 50600 bytes (0.00%), skipped.
nexus_6_0134.jpg 1607x2896 24bit N Exif IPTC ICC JFIF [OK] 1889349 --> 260524 bytes (86.21%), optimized.
unnamed.jpg 480x800 24bit N JFIF [OK] 36364 --> 24816 bytes (31.76%), optimized.

以上结果已将 JPG 文件压缩为 250K 大小的文件。

要压缩所选文件，请使用以下命令:


jpegoptim file_name.jpg file_name1.jpg file_name2.jpg

有关 jpegoptim 的更多详细信息，请使用以下命令:

$ man jpegoptim

示例输出应如下所示 -

NAME
   jpegoptim - utility to optimize/compress JPEG/JFIF files.
SYNOPSIS
   jpegoptim [ options ] [ filenames ]
DESCRIPTION
   jpegoptim is used to optimize/compress jpeg files. Program supports lossless optimization, which is based    on optimizing the Huffman tables. And so called "lossy" optimization where in addition to optimizing
   Huffman tables user can specify upperlimit for image quality.
OPTIONS
   Options may be either the traditional POSIX one letter options, or the GNU style long options. POSIX style    options start with a single ``-'', while GNU long options start with ``--''.
   Options offered by jpegoptim are the following:
   -d, --dest=
.....................

优化 PNG 图片

OptiPNG 是一款简单易用的实用工具，可在不丢失任何信息的情况下优化 PNG 图片。该程序还可以将外部格式(BMP、GIF、PNM 和 TIFF)转换为优化的 PNG 格式，并执行 PNG 完整性检查和校正。

要安装 OptiPNG，请使用以下命令 –

$ sudo apt-get install optiPNG

示例输出应如下所示 -

Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
gcc-4.8-base:i386 libasn1-8-heimdal:i386 libasound2:i386
libasound2-plugins:i386 libasyncns0:i386 libavahi-client3:i386
libavahi-common-data:i386 libavahi-common3:i386 libbit-vector-perl
libcapi20-3:i386 libcarp-clan-perl libclass-method-modifiers-perl
libcups2:i386 libdata-random-perl libdate-calc-perl libdate-calc-xs-perl
libdrm-amdgpu1:i386 libdrm-intel1:i386 libdrm-nouveau2:i386
libdrm-radeon1:i386 libedit2:i386 libelf1:i386 libexif12:i386 libexpat1:i386
libffi6:i386 libflac8:i386 libfontconfig1:i386 libfreetype6:i386
libgcrypt11:i386 libgd-perl libgd3:i386 libgif4:i386
libgl1-mesa-dri-lts-wily:i386 libgl1-mesa-glx-lts-wily:i386
libglapi-mesa-lts-wily:i386 libglib2.0-0:i386 libglu1-mesa:i386
libgnome2-gconf-perl libgnutls26:i386 libgpg-error0:i386 libgphoto2-6:i386
.........................................

要查看PNG的实际大小，请使用以下命令

$ ls -lh /home/linux/Desktop/logo.png

示例输出应如下所示 -

-rw-rw-r-- 1 linux linux 3.4M Mar 3 12:05 /home/linux/Desktop/logo.png

以上图片的实际文件大小为 3.4MB，现在运行以下命令压缩该文件 -

$ optipng /home/linux/Desktop/logo.png

示例输出应如下所示 -

Copyright (C) 2001-2010 Cosmin Truta.
** Processing: /home/linux/Desktop/logo.png
2560x1920 pixels, 3x8 bits/pixel, RGB
Input IDAT size = 3506320 bytes
Input file size = 3511513 bytes
Trying:
zc = 9 zm = 8 zs = 0 f = 5IDAT size = 3260520
zc = 9 zm = 8 zs = 1 f = 5IDAT size = 3257566
Selecting parameters:
zc = 9 zm = 8 zs = 1 f = 5IDAT size = 3257566
Output IDAT size = 3257566 bytes (248754 bytes decrease)
Output file size = 3257623 bytes (253890 bytes = 7.23% decrease)

现在检查log.png的大小。使用以下命令-

$ ls -lh /home/linux/Desktop/logo.png

示例输出应如下所示 -

-rw-rw-r-- 1 linux linux 3.2M Mar 3 12:07 /home/linux/Desktop/logo.png

如上所示，tecmint.png 文件的大小已减少至 7.23%。在任何图像查看器应用程序中打开压缩后的图像，您会发现原始文件和压缩文件之间几乎没有区别。

批量 PNG 图像压缩和优化

要一次性压缩多个 PNG 图像，请使用以下命令 -

$ cd /home/linux/Desktop/img/
~/Desktop/img$ optipng *.png

示例输出应如下所示 -

Copyright (C) 2001-2010 Cosmin Truta.
** Processing: LOGO122.png
149x90 pixels, 4x8 bits/pixel, RGB+alpha
Input IDAT size = 5026 bytes
Input file size = 5083 bytes
Trying:
zc = 9 zm = 8 zs = 0 f = 0IDAT size = 4934
Selecting parameters:
zc = 9 zm = 8 zs = 0 f = 0IDAT size = 4934
Output IDAT size = 4934 bytes (92 bytes decrease)
Output file size = 4991 bytes (92 bytes = 1.81% decrease)

有关 optipng 的更多详细信息，请使用以下命令 -

$ man optipng

示例输出应如下所示 -

NAME
   OptiPNG - Advanced optimization program for Portable Network Graphics (PNG)
SYNOPSIS
   optipng [-? | -h | -help]
   optipng [options...] files...
DESCRIPTION
   The OptiPNG program shall attempt to optimize PNG files, i.e. reduce their size to a minimum, without          losing any information. In addition, this program shall perform a suite of auxiliary functions like
      integrity checks, metadata recovery and pixmap-to-PNG conversion.
   The optimization attempts are not guaranteed to succeed. Valid PNG files that cannot be optimized by this    program are normally left intact; their size will not grow. The user may request to override this
   default behavior.
................................

恭喜!现在，您已经了解如何在 Linux 命令行中优化和压缩 JPEG 或 PNG 图像。我们将在下一篇 Linux 文章中学习更多此类命令。敬请期待!