Caesium, Compresses Images, With Previews

Martin Brinkmann
Jul 27, 2010
Updated • Jun 21, 2018
Software, Windows software

Images and photos can often be compressed to reduce storage space requirements. If used with care, image compression can reduce file sizes of images and photos anywhere between 10% to 90%, without producing a visible loss in quality.

Webmasters for instance need to make sure the images they post on their websites are optimized to avoid prolonged loading times for visitors.

But compressing images can also be beneficial for other computer users, for instance before sending the latest vacation photos to friends and family.

Note: The developers of Caesium have released an online version that supports the core functionality that Caesium provided. The web version limits the size of images to 5 Megabytes though.


image compressor
image compressor

Caesium is a lightweight image compressor that comes with all the bells and whistles one would expect.

The Open Source software needs to be installed before it can be used. Images that you want to process are then loaded into the interface by clicking on the Add Files button in the main menu.

Each image is listed with its name, current file size and full path on the local computer system.

The lower half of the screen lists the image compression settings that are applied to all images when they are processed. The program will convert them by default to jpg images with a quality setting of 80%. Both the output format and the quality can be changed easily on the screen.

Additional options include the selection of an output directory, switching to a different output format, and an (optional) suffix.

A click on the preview button renders a preview image and displays it beneath the original image in the program interface. The preview option enables you to compare the original image with the compressed version of the image to see if there is the need for fine tuning the image compression settings.

Caesium displays the new size, ratio and quality next to the original image information. It is important to set the image container size to original under View > Image Container Size. The default image size is to small to compare the image's quality thoroughly.

compress images
compress images

A click on the compress button compresses the images in the queue, and either saves them in the same directory as the input images, or in the output directory location.

Caesium Features

  • Resize your pictures up to 90% preserving the file format. The software use an intelligent file compressing method.
  • Batch processing. Compress in a few second as pictures as you like.
  • Most common file format are supported. (JPG, BMP, PNG, GIF, WMF)
  • Easy preview, with a twin picture box that display the final result with a button.
  • Picture-by-picture compression level. You can set every single compression level at every picture.
  • Compression level can be set with an easy slider.
  • Drag&Drop. Drop your pictures directly into the list.
  • Rename all files with a custom suffix.

Closing Words

Caesium does an excellent compression job most of the time. The standard output settings seem to work really well, and usually do not generate an output image of noticeable lower quality than the original. Depending on the original image, it can happen that the new compressed size of the image is in fact larger than the original size.

The Open Source software Caesium is available for download at the developer's website over at Sourceforge.

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  1. Joe said on July 27, 2010 at 12:44 pm

    It looks less powerful and less flexible than RIOT:

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