Webcomic Image Formats
A common mistake I see in webcomics are image files that are saved in an incorrect format. Choosing the correct image format, or filetype, for your webcomic is dependent on the content of your image. Ideally, you want to have an image that has the lowest file size possible, while retaining the best image quality for the artwork. You can see the three most common web image filetypes in the quick reference chart below.
|Good compression and good image quality overall||Complex transparencies||Ideal for typography, solid lines & colours|
|Best compression at the expense of image quality||No transparencies||Ideal for photographs and gradients|
|Okay compression, using more colours increases filesize||Simple transparencies||The only format that allows animation|
PNGs are a relatively new image format that has two variants, PNG-8 and PNG-24, based on the variety of colours you can use. PNG-8 is limited to 256 colours, but comes a lower file size; PNG-24, on the other hand, can have up to 16 million, but with a higher file size. Both variants, unlike GIFs, support full alpha (complex gradient) transparencies. PNGs handle solid colours and edges very well, so if you have a lot of text, lines, blocks of colour and no transparency, you want to save your comic as PNG-8 every time.
JPGs, or JPEGs, are the most common image format on the web today and is primarily used for photographs. In the realm of webcomics, you should only be using JPGs if your artwork has lots of gradients or painted colours and little to no text. The reason for this is that JPGs do not handle edges very well, and you tend to see artifacts (image compression errors) in all but the highest-quality JPGs. On the plus side, JPGs boast the most effective image compression of the three file formats, although you will have to sacrifice quality in order to achieve lower file sizes.
GIFs were the standard for images with transparency, solid colours and lines before the more advanced PNGs rolled around. They don’t compress as well, have limited colours (unless you want a file hundreds of megabytes in size), and simulates complex transparencies with a method called dithering, which doesn’t look good at all. Nowadays, the only reason you should ever be using a GIF is if you are creating an image with multiple frames — an animated GIF.
In this day and age where just as many people are reading comics on their phone as they are on their desktop computer, image quality and file size has never been a more important issue. Keeping your file size low and your image quality high is going to be a constant juggling act, but as long as you know what to look for — solids vs. gradients — you shouldn’t have a difficult time deciding which format to go with.