Before I talk about this specific free program I would just like to make a couple of general comments.
- You should only use image compression when you need to (sounds obvious) e.g. when you want to use the images on a website, forum or maybe in email. I wouldn’t use it just to save image on your hard drive or something like that.
- Always work on a copy of your image(s) or ensure you save the compressed image as a copy. It does reduce the quality of the image slightly so, if you decide to print it at a later date, it may not be as good as it was.
Image compression is a really useful tool is you are working in a situation where you want the image to be a smaller file size but not physically smaller. OK you will loose a little quality and this will vary from program to program but often so little that the image itself will hardly appear different on the internet.
Caesium Image Compression worked really well irrespective of it being free. The example we tried the compression factor was set to “50” this reduced the actual file size from 3.70 MB down to 1.57 MB with no discernible change in image quality, especially viewed in the internet. This is great when it comes to the speed of downloading a web page. Whilst many people think that isn’t so important in these days of superfast broadband but there are still a lot of people on slow /mobile connections even in countries like the UK and USA.
I did take the time to zoom right in to a couple of the images I had compressed and again saw little difference, if I wanted to be really picky then I would say they may have lost a very small amount of their contrast.
For my second test I compressed a full directory of images (158) and the size was reduced from 469 MB to 90 MB which is a tremendous saving. The program handles batches with no problem at all. You can either use the same compression factor on all the image, which is how I did it, or you can set it differently per image. Whilst I wouldn’t really send that number of file by email you can see how it would make (perhaps slightly smaller collections) it possible to send a set to a friend,. maybe telling them you can supply the uncompressed version of any image they wanted to print in large format.
This is a great free program to use when you need your images in a compressed format but again I would warn against using compression on any images by default, it may effect printing or editing at a later date.
Caesium Image Compression software is only available for Windows Operating Systems. You will find the official website here: http://caesium.sourceforge.net/