Understanding FLIF – A new, lossless image compression format

Since the arrival of digital photography, most of us are used to recording our images in RAW or sometimes in JPEG, in camera. RAW is digital photography’s equivalent of the negative in film photography. Simply put, it is collection of “RAW” information straight from the pixel. This information then needs to be put back together like the pieces in a puzzle. This process is called “de-mosaicing”, after that, white balance and tonal range information gets added to the file. It should be kept in mind that, all of this happens, after the picture is taken, and the RAW data is recorded. Therefore, technically, speaking, RAW is not exactly a file format, it is simply a set of Binary Information i.e. Ones and Zeros that contains Red, Green and Blue Pixel information.

Therefore, when it comes to publishing, printing and delivering images to printers, or clients, photographers and the photography industry is used to certain, set, tried and tested image formats – TIFF, JPEG, PNG and BMP. RAW files are never used for any of these purposes because, there just isn’t any way of displaying RAW data. When you click a a photograph in RAW and play it back in your camera, the camera actually shows you a JPEG thumbnail version of the file. Even when you directly open your RAW file in an editing software such as Photoshop or Lightroom, the software, first converts the RAW data into a readable format (usually TIFF) and then displays it to your screen.

Each of these formats has its own advantages and disadvantages. Some of these formats are “Lossy” compressions such as JPEG. A lossy compression is simply a format in which you loose resolution and detail when you compress the file. Some of the data is simply thrown out when you save the file and never recovered again Some for of these compressions such as TIFF and PNG are Loss-less compressions which implies that data gets compressed when you save the file, and gets de compressed when you read it again.

As the internet rapidly expands, a crucial aspect of file formats has become the file size and load times. The most crucial factor is delivering image quality in a compact file size. Most importantly, this has to be done without consuming too much internet bandwidth. More importantly, the file has to deliver the same quality and load time on a mobile device as on a desktop computer.

In 2010, Google released a new file format called WebP, which promised to speed up the internet by shrinking file size without compromising on quality. 5 years on, and that format has not really caught on.

Now enters Free Lossless Image Format or FLIF as it is called.

The format looks promising as it claims to deliver (on average) 35% smaller than typical PNG files and 37% smaller than lossless JPEG 2000 formats.

As per its creators “Even if the best image format was picked out of PNG, JPEG 2000, WebP or BPG for a given image, depending on the type of image (photograph, line art, etc), then FLIF still beats that by an average of 10% in our comparisons.” This is very impressive.

The biggest advantage of FLIF is that it works on all kinds of images. It’s developers say “FLIF does away with knowing what image format performs the best at any given task. You are supposed to know that PNG works well for line art, but not for photographs. For regular photographs where some quality loss is acceptable, JPEG can be used, but for medical images you may want to use lossless JPEG 2000. And so on. It can be tricky for non-technical end-users.”

Another big advantage of FLIF is that it is a progressive file format, unlike other formats that are Interlaced. Interlacing simply means, that your images is divided into rows and columns and are then put back together when on display on a screen. A significant disadvantage of this is that, on a slow internet connection or when viewing images on a mobile device, your image will not get a preview of the image, until the entire image has been downloaded. This can be commonly seen when your are viewing images on a slow connection, and the images loads in parts, from top to bottom. FLIF, because it is a progressive format, the entire image is created at once, not in rows and columns, therefore you only need to download the first part of the file to get a quick and reasonable preview of an image.

Here is a short video from its developer that demonstrates this feature, and its quickness. Note, you get a reasonable preview of the image, with only 1% of the image downloaded.

At this moment, FLIF has its disadvantages though. FLIF is a work in progress, and there are things such as EXIF support that are missing, so photographers may not be the quickest to adopt this format. Another thing that developers are working on are CMYK colour space support so that the format can be easily adapted for printing as well as web browsing support.

So what exactly does it mean for photographers? Well, most importantly, it delivers image quality in less than half the size, which will ensure quick loading of images, especially on slower connections. So anywhere that your images are shown or published, be it on the web or your portfolio website, or in simply day to day activities such as uploading to social media or emailing to a client or a friend, it will eat up less space, without compromising on resolution.

And not to forget, FLIF is completely free. There are no royalty fees or software patents attached to it.

If you want to know more about the format you can visit the official website or download the source code from GitHub. 


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