The process of making an animated sticker is much more complex than a static sticker. In addition to having animation skills, sticker creator must follow the technical rules of LINE and Apple iMessage. In this article, we will give you guidance and tips on how to make animated stickers for LINE and Apple iMessage.
Getting to know the APNG, the animated sticker file format
Before we get into the technical stuff. First, you need to know the animated sticker file format. LINE and Apple iMessage are using the APNG (Animated PNG) file format. The file extension remains .PNG. Regular PNG contains only one image, where the APNG file contains the PNG format sequence. When opened by an APNG-enabled app, the sequential image will become animated.
Apple iMessage actually supports GIF files, but APNG remains superior to GIF because APNG supports alpha and more colors that make images sharper. In addition to better image quality, in some cases, APNG images have smaller file sizes than GIFs.
The Technical Process on Creating Animated Stickers
The work of sticker animation depends heavily on sticker creator’s ability. The process of making the same as making an animated film and can use any animation software.
You need to set the frame rate or FPS (Frame Per Second) as low as possible without damaging the animation quality. Most animation software has the ability to change FPS. FPS settings are important, because of the limit of APNG file size the amount of FPS will affect the size of the generated APNG file. In addition, to file limits there is also a first frame rule in LINE that will be explained below.
FPS and File Size
APNG file size limit for LINE is only 300 KB with 320 x 270 pixels image size, iMessage has bigger file size limit, that is 500 KB, but with bigger image 408 x 408 pixels. With very small file size limits, we recommend to set FPS ranging from 8 to 12 FPS. Sticker published by STCKRmarket uses 10 FPS, meaning that in one second there are 10 frames of images, 10 FPS is enough to produce smooth motion without generating many frames.
First Frame as Thumbnail
The first frame of the animated sticker is very important, it works as sticker thumbnail in the sticker drawer. Based on the LINE sticker guidelines, the first frame must illustrate the emotion or message of the sticker. For example in the picture below, the first frame illustrates the shocked face instead of the transition expression to the shock on the other frame.
As for Apple iMessage, there is no rule about the first frame, but we strongly recommended to apply the same practice with LINE sticker so that the expression of the sticker thumbnail on the sticker drawer is clearly illustrated.
APNG Duration and Loop
Apple iMessage does not limit the amount of animation duration. But, in order to simplify the process, a submitted sticker must follow the APNG file for LINE Sticker. Every sticker must have a full duration of 1, 2, 3 or 4 seconds. Other durations of APNG will be rejected, for example, 1.2 seconds. Please pay close attention to the total duration when you make the APNG.
In addition to the duration in LINE, there is also a rule the number of looping APNG files that is a maximum loop not exceeding 4 loops. If the animation duration is 1 second, then the loop count is 4 times or less; 2 seconds 2 loop or less; 3 and 4 seconds would results in 1 time loop due to the maximum limit of APNG duration is 4 seconds.
The Making of APNG
After creating animation with your animation software of choice, export it into PNG sequence. The APNG will be made from the PNG image sequence. But before creating APNG files you must compress PNG files into smaller ones using the PNG optimizer tool. We use PNGYU (available for Windows and macOS) to reduce the PNG file size significantly. If your sticker design uses limited colors, you should reduce the maximum number of colors to make the final PNG sequence file size smaller.
Once optimized, it’s time to create an APNG file. There are many APNG maker apps available, from open source to pay version for Windows and macOS operating systems. For MacOS users we recommend using our PNG Animator review, and Windows user can use APNG Assembler app.
When making the APNG file pay attention the loop count and duration, make sure to follow the rules as mentioned before. For compression, we recommend to use 7zip which will result in a smaller APNG file size than zlib . After done making APNG make sure the file size is below 300 KB for sticker LINE and 500 KB for iMessage sticker.
Creating animation sticker might feel like too complicated. But, once you are getting familiar with the process, it would just take a little longer working time than creating static stickers. You can consider it as a little investment because in general animation stickers perform better on sales and download numbers.
Still not sure your animation sticker already fulfill all Line’s and Apple iMessage’s requirements? or have useful tips on creating animation stickers? Feel free to brag or ask a question in the comments.