Tuesday 07th January 2014
GIF, JPEG, PNG, TIFF - those of you who are new to the world of digital images might feel a little overwhelmed by the acronyms alone, and they can seem a bit daunting to us old hands as well sometimes. When you're saving your perfectly edited image, whether it's a digital painting or a photograph of your latest sculpture, it can sometimes seem completely impossible to navigate the wide arrays of file formats and settings that you are presented with. The four listed above are really the only ones you're like to need to work with, and we'll take you through the merits of each one.
GIF, which is actually supposed to be pronounced 'jiff', is one you can discount almost immediately. It was quite popular in the early days of the web, but unless you're creating work that has a very limited colour palette, it's not your best option. It can be very useful for maintaining minimal file sizes, but the reason it excels at that is its limited colour palette. It's great for animated cats, but it's not worth using for your art images.
JPEG is by far the most popular image file format for web-based imagery. It has a great blend of low file size and a wide colour palette, and it can be read by virtually every browser on every device ever made. When saving your JPEGs, the most important choice to make involves the amount of compression you're going to use, typically presented as a range from 0-100 (although sometimes from 1-10 or 1-12). Unless you have truly exceptional visual acuity, you can save yourself some file size by starting out around 80 (relatively large file size, but near-perfect image representation). In many cases, you can reduce all the way down to 65 or even 60 without any noticeable impact on the image quality. This can be very helpful when creating large numbers of image thumbnails or if you want larger images to load more quickly.
PNG is a special case image format, that can have some very specific uses in web design, for example when designing or customizing your Gallereo page. The main thing that makes PNG stand out is that it is capable of including something called an 'alpha channel', which allow PNGs to contain transparent elements. Each digital image contains 3 channels, Red/Green/Blue, which are each greyscale versions of your image. White pixels on the red channel show up as red, etc. The alpha channel is a fourth channel that controls the transparency of each pixel. It also has a relatively good file size to quality ratio, but unless you're using transparency, JPEG is usually a better option. If you do opt to use PNG, be sure you're using PNG-24 not PNG-8.
TIFF is what you want to be using for saving your full-resolution images. It is what's known as an uncompressed file format, meaning that it won't compromise your image quality at all, and newer versions of the TIFF standard support ZIP compression and another form of lossless compression known as LZW. Either way, though, TIFF files wind up with extremely large file sizes - a JPEG that is 2 megabytes in size might be as much as 20 megabytes when saved in the TIFF format. Because of this, reserve TIFFs for sending to your printer, and don't use them for the web.
Posted on January 07th 2014 on 07:07pm