Or, run the following command in your terminal. Almost all the tasks which can be performed using usual GUI tools can be done using ImageMagick’s convert command line tool.įor a complete list of all the things convert command can do, see the convert man page. In a similar way, other attributes can be modified. And of course, larger image size too as compared to high compression levels. └ Note: Lower compression level means better quality of image. To change the quality index (compression level) of a JPEG image, use: convert test.jpg -quality 15 test_2.jpg To change contrast level of an image, use : convert -brightness-contrast x5 test.png test_2.png To change image brightness, use: convert -brightness-contrast 10 test.png test_2.png convert test.png test.jpg Change Image Brightness and ContrastĬonvert can be used to modify attributes such as brightness, contrast, compression level, etc. It supports huge number of formats.īelow is an example command to convert a PNG image to JPG format. The convert tool can convert images from one image format to the other. # This keeps the width but changes height to 200 Convert Image Format # This keeps the height but changes width to 300 # 300 is the width to be converted to in pixels, and 200 is the height in pixels # Here test.png is the source image, test_2.png is the name for converted image To resize an image, we use the flag -resize: convert test.png -resize 300x200 test_2.png To install on CentOS and Fedora, run: yum install ImageMagick Resize an Image using Convert └ Note: For older Ubuntu versions (version 14.04 and below), you need to use apt-get instead of apt. If it is not installed, we can install it on Ubuntu and Debian with: sudo apt install imagemagick Installing ImageMagick ( convert)įirst verify if ImageMagick is already installed using: convert -version It consists of many tools with number of options for image modification, conversion, etc. If you need to do some more advanced find commands that use regex this should help.ImageMagick is a suite of image modification software for Linux. Make sure to compress your images with lossless ( guide) or lossy compression ( guide). You can use the top command and look for jpegoptim processes once in a while.Ĭheck the folder size again du -sh foldername sudo apt-get install screenĬreate a new screen session, press space or enter at the intro screen screenĮxecute the script bash ~/scripts/batch-image-resize.shĭetach the screen with Ctrl A and pressing D (detach). Screen will ensure the batch command keeps on running even if your SSH session is terminated. #resize png or jpg to either height or width, keeps proportions using imagemagick It will overwrite your original images so make sure you have a backup before running this!įOLDER="/var/www//wp-content/uploads" WIDTH is the max width and HEIGHT is the max height. Paste the script below, remember to change the FOLDER variable!įOLDER is the absolute path to your image folder Now we can move on to batch resizing Batch Resize Images with Linux with ImagemagickĬreate the following script mkdir -p ~/scripts Note that this overwrites your original image! convert image.jpg -resize 600x400\> image.jpgĬheck the image was resized identify -format "%wx%h" image.jpg This will automatically preserve the aspect ratio of the image too. You can resize the image if it is larger than the specified dimensions. For example: Alternatively if using a batch file you might try something like this: set CDTI 'c:program filesSoftinterface, IncConvert Document To ImageCDTI.EXE '. You will see the resolution, width is first then height. We can use the identify command to get the width ( %w) and height ( %h) identify -format "%wx%h" image.jpg Batch Resize Images using Linux Command Line and Imagemagickįirst we need to install Imagemagick from the repository on Debian or Ubuntu sudo apt-get update If you want to install Imagemagick on CentOS see this guide. This guide shows you how to batch resize jpg and png files using Imagemagick on Ubuntu or Debian. If you never had any image size restrictions or automatic resizing on your site, it can be extremely convenient to batch resize those images in Linux. The most common culprit is image size or lack of compression. Note that the page index starts at 0 instead of 1. The number inside the bracket is used to select a page. Large images means a large page size which means slow WordPress page load times for users. To convert a single page of PDF to image, use the following command: convert -density 150 presentation.pdf 0 -quality 90 test.jpg.
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