What is the GIF format?

1What is a GIF file?

GIF stands for Graphics Interchange Format. CompuServe created it in 1987 to exchange color images over the slow connections of the time. In 1989 version 89a was released, which added transparency and the ability to store several frames in one file, giving rise to the looping animations we now know as “GIFs.”

It remains relevant because it plays automatically, with no need to press “play,” practically everywhere: chats, social networks, emails and forums. That is why it is the format of reaction images and animated memes.

2How does a GIF work inside?

Each frame of a GIF uses a palette of up to 256 colors chosen for that image. The file stores the palette and, for each pixel, a number that points to a color. It then compresses those numbers with the LZW algorithm, with no loss of information on that palette. Each frame can include a delay time, and a flag indicates whether the animation repeats.

Because there are only 256 colors, photographs and gradients suffer: banding or dithering dots appear. Flat drawings, logos and animations with few colors, on the other hand, look good.

• Palette of up to 256 colors per frame.
• Single-color transparency, with no soft edges.
• Animation made of frames, each with its own delay.

3Advantages and limitations of GIF

Advantages: autoplay, near-total compatibility, no sound or controls, and easy sharing. Limitations: few colors, transparency without soft edges, no sound, and a very high file size when the animation is long or has a lot of motion, because each frame is stored almost like a full image.

A GIF a few seconds long can weigh several megabytes. That is why many sites internally convert GIFs to short video, which is much lighter and allows higher quality.

4GIF vs. PNG, WebP and video

For a still image, PNG is superior: more colors, soft transparency and better compression. For a short animation with few colors, GIF is still practical. For animations with higher quality and lower file size, animated WebP is a great option on today's web. And for clips several seconds long with lots of detail, a looping video is usually much lighter than a GIF.

If your GIF has poor quality, there is no real way to recover colors that aren't in the file. It's best to go back to the original video or image sequence and export again.

5Common GIF problems

The most common is file size. To reduce it, lower the dimensions, reduce the frames per second, trim the duration or limit the colors. “Compress image” and “Resize image” can help with still images. Another problem is the “blotchy” look in photos, caused by the limited palette, and jagged edges when using transparency over different backgrounds.

If you want to include the GIF in a document, keep in mind that a PDF doesn't play the animation: “Images to PDF” will use only one frame. For animations, share the file separately.

6Practical tips for GIFs

Keep GIFs under a few hundred pixels wide if you use them in chats or email, and avoid gradient colors. If you are going to make a meme, the “Meme maker” tool in Rayo PDF GO works for still images with text, and you can export them in a lightweight, compatible format.

On the privacy side, remember that a GIF downloaded from the internet may be a copyrighted image. And as with the rest of the site's tools, processing happens on your device, without sending your files to any server.

One last guideline: if you are going to use a GIF as a reply in a chat, smoothness matters less than clarity. Ten to fifteen frames per second are usually enough, and a duration of two to four seconds keeps the file manageable. If the motion needs to be smooth and long, a short looping video is better.

7How to get the most out of GIF in Rayo PDF GO

For still GIF images, “Compress image” and “Resize image” help reduce file size, and “Crop image” removes what's left over. If you want to build a document with several images, “Images to PDF” gathers them, although remember that an animation will end up as a still image.

If your goal is a meme or an image with text for chats, “Meme maker” lets you overlay text on an image. And if you need a higher-quality version, use the original material, whether a video or an image sequence, because a GIF doesn't store more information than it shows.