It’s an RGB. We pronounce the abbreviation RGB as individual letters, and the letter "R" starts with a vowel sound; therefore, it takes the article "an".

It’s an RGB. We pronounce the abbreviation RGB as individual letters, and the letter "R" starts with a vowel sound; therefore, it takes the article "an".

An RGB image has three color channels.

A RGB image has three color channels.

Remember, when choosing between "a" and "an", it's the sound of the following word, not the spelling, which is important.

You can use an RGB color model to achieve certain effects.

And we put "an" before the abbreviation RGB (Red Green Blue—color model).

The color for a page background is often specified by an RGB value.

Follow the same convention with other abbreviations and words that begin with "R" and are pronounced as separate letters; for example, we say an R (not "a R") and an R&D project.

Write an R in cursive.