Opacity

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2025-06-06

What is "Opacity" in the Computer?

Opacity means the opposite of transparency. In the computer, opacity and transparency are terms used in image editing, video editing, and graphic design software. If we have an object or layer with 50% opacity, that means it's semi-transparent. 0% opacity means it's 100% transparent and therefore invisible. On the other hand, 100% opacity means it's fully opaque and not transparent at all.

A panel labelled "Layers." In it, a dropdown list button reads "normal," and a spinner reads "Opacity: 100%." A filter icon button and a hamburger menu button can be seen. The main area is a list with 3 items, labelled "Group 2," "Paint Layer 1," and "Background." The paint layer is indented to indicate that its a child of the group. Several icons can be seen on each layer: an eye icon, a checkbox, a padlock, an icon with the Greek latter alpha, and checkerboard icon, and a brick wall icon. At the bottom, several buttons: a plus with a dropdown, a duplicate icon, a down arrow and up arrow, an icon that resembles sliders with a dropdown, and a trash icon. — Krita's "`Layers`" docker, featuring a group layer, a paint layer (selected), and a locked background. Observe that there is a slider to change the opacity of the selected layer. In most image editing software, you will find a similar graphical user interface.

In modern digital image editing, the individual pixels of images and layers can have varying degrees of opacity, also known as their alpha value in the RGBA format. What this means is that the opacity of the layer is multiplied by the opacity of the pixel, e.g. a pixel with 25% opacity has 25% opacity if the layer has 100% opacity, but if the layer has 50% opacity then the opacity of the pixel is 50% of 25%, which is 12.5%.

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