How to compress images using linux commandline

JPEGOPTIM – To compress JPEG images with out loosing the quality.

OPTIPNG – To optimize and compress the images without loosing the quality.

Install jpegoptim in Linux

To install jpegoptim on your Linux systems, run the following command from your terminal.

On Debian and it’s Derivatives

# apt-get install jpegoptim
or
$ sudo apt-get install jpegoptim

On RedHat based Systems

On RPM based distros you need to enable to EPEL repo which can be installed directly with commandline.

# yum install epel-release
# dnf install epel-release    [On Fedora 22+ version]

Next install jpegoptim program from the repository as shown:

# yum install jpegoptim
# dnf install jpegoptim    [On Fedora 22+ version]

How to Use Jpegoptim Image Optimizers

The syntax of jpegoptm is:

$ jpegoptim filename.jpeg
$ jpegoptim [options] filename.jpeg

Let’s now compress the following codingsec.jpeg images, but before optimizing the image, first find out the actual size of the image using du command as shown.

$ du -sh codingsec.jpeg 

6.2M	codingsec.jpeg

Here the actual file size is 6.2MB, now compress this file by running:

$ jpegoptim codingsec.jpeg

Our file is compressed down by 30%

If you want more

 jpegoptim --size=250k codingsec.jpeg

Compress or Optimize PNG Images from Command Line Program

OptiPNG is a command line tool used for optimize and compress PNG (portable network graphics) file without losing its original quality.

The installation and usage of OptiPNG is very same as to jpegoptim.

Install OptiPNG in Linux

To install OptiPNG on your Linux systems, run the following command from your terminal.

On Debian and it’s Derivatives

# apt-get install optipng
or
$ sudo apt-get install optipng

On RedHat based Systems

# yum install optipng
# dnf install optipng    [On Fedora 22+ versions]

Note: You must have epel repository on your RHEL/CentOS based systems to install optipng program.

How to Use OptiPNG Image Optimizer

The general syntax of optipng is:

$ optipng filename.png
$ optipng [options] filename.png

Let us compress the codingsec.png image, but before optimizing, first check the actual size of the image as shown:

harry@codingsec~/img $ ls -lh codingsec.png 
-rw------- 1 codingsec codingsec 350K Jan 19 12:54 codingsec.png

Here the actual file size of above image is 350K, now compress this file by running:

harry@codingsec~/img $ optipng codingsec.png 
OptiPNG 0.6.4: Advanced PNG optimizer.
Copyright (C) 2001-2010 Cosmin Truta.

** Processing: tecmint.png
1493x914 pixels, 4x8 bits/pixel, RGB+alpha
Reducing image to 3x8 bits/pixel, RGB
Input IDAT size = 357525 bytes
Input file size = 358098 bytes

Trying:
  zc = 9  zm = 8  zs = 0  f = 0		IDAT size = 249211
                               
Selecting parameters:
  zc = 9  zm = 8  zs = 0  f = 0		IDAT size = 249211

Output IDAT size = 249211 bytes (108314 bytes decrease)
Output file size = 249268 bytes (108830 bytes = 30.39% decrease)

As you see in the above output, the size of the codingsec.png file has been reduced up to 30.39%. Now verify the file size again using:

harry@codingsec~/img $ ls -lh codingsec.png 
-rw-r--r-- 1 codingsec codingsec 244K Jan 19 12:56 codingsec.png

Open the image is compressed in any image viewer application, you will not find any major differences between the original and compressed files. The source and compressed images will have the same quality.

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