What is in alpha channel
When we look at images or videos with complex graphic elements or editing made by professionals, we don’t think about how they did it. However, with the capabilities of modern editors, every feature has a distinct meaning and even amateurs can create a lot of interesting things using them.
When complex manipulations with visuals are needed, alpha channels play a significant role – in fact, one of the simplest examples are PNG images with a transparent background.
Now, what does a transparent background mean? This is exactly what it sounds like! So, if you try to combine a picture with transparent elements with a colored background, only the already visible parts will be placed over it. This is possible thanks to the alpha channel, which, simply put, is a component that affects the level of opacity in a file.
How alpha channels work
An image file typically stores color information for each pixel. Alpha channels add an extra layer of information that determines how visible each pixel is.
Its values usually range from 0 to 255, where 0 means full transparency and 255 – full opacity. The remaining values indicate partial visibility, and its intensity depends on the specific number chosen. By adjusting the value, the creator can show parts of one image through transparent areas of the other one when it’s placed over it.
Common formats supporting alpha channels
For images, the most common formats that support transparency channels are PNG, TIFF, PSD, and SVG.
Many video formats and codecs also have alpha channels, for example, WEBM (VP8 and VP9), MOV/QuickTime (HEVC, Apple ProRes 444), FLV, and AVI.
If you want to know whether any file you have has an alpha channel, most image and video editors can display information about it. For example, in Adobe Photoshop, you can check if there’s an alpha channel in an image in the "Channels" tab.
As for videos, in editors like Adobe After Effects, DaVinci Resolve, or some other one you can enable the display of the alpha channel in the preview settings and see if it is there.
In addition, there are online services and software where you can check files’ properties, especially for the popular PNG and WEBM formats.
With the development of software, working with alpha channels is also supported by an increasing number of video and image editors. There are online video editing tools that allow you to place transparent files over another background.
However, often, professional video editing software is still needed to save files with a transparent canvas. While some tools can save in .webm or .png, this does not guarantee that the canvas will be transparent, as not all tools support alpha channels to that extent. Therefore, before editing your assets, always verify the supported formats and check if downloading with a transparent canvas is an option.
Applications of files with alpha channels
Despite the simplicity of the effect, images and videos that support alpha channels are viable in a variety of ways. The ability to adjust the transparency of the entire file or some of its parts simply opens up too many opportunities for both professionals and amateurs.
For example, when using chroma key backdrops, the alpha channel defines the transparency of a green (or any other color) background. It can then be replaced with another image or video sequence. This way, when editing footage of people filmed in one room, you can make it seem like they are visiting many different locations.
Transparency also helps when working with multiple layers and when creating complex scenes with overlapping pics and clips. For example, you can place one layer with transparent areas on top of another image or scene.
In addition, transparency is a great instrument for streamers and vloggers as a whole. Animated or static logos and overlays are great for helping viewers remember the creator and show what visual vibes to expect from them. Video editing tools can be utilized to add watermarks to videos, ensuring visibility while allowing the underlying content to subtly show through. Image files with transparency work best for this purpose.
Emojis are also quite popular, especially when it comes to memes. While they are often left with a fully visible background to add humor, emojis with a transparent background are no less common.
Motion graphics for titles, animations, and other graphic overlays often use alpha channels for smooth blending and compositing.
During image editing, removing unwanted objects from an image can be done more precisely with tools that utilize alpha channels.
FAQs
What is an alpha channel?
It’s an extra color channel that allows adjusting the level of transparency in a specific area of a picture or video. It helps to overlay images, make them semi-visible, and also partially show other elements through transparent areas.
What video formats support transparency?
Such formats include WEBM, CineForm, FLV, MOV, AVI, and others. MOV and AVI, however, require special codecs to display video with an alpha channel without issues.
What image formats support transparency?
The main formats are PNG, TIFF, PSD, BMP, TGA, and SVG. Most of them work with transparent elements without any special conditions, but in the case of BMP, you need to be sure to use the extended version, as the standard one doesn’t support alpha channels.
Conclusion
An alpha channel is a component that allows visual format files to have transparent sections and settings. This feature enables the creation of multi-layered images and videos with visible or semi-visible elements. This makes it an indispensable tool for visual effects, chroma keying, compositing, and animation.
