What Is TGA? A Guide to the Truevision Targa Format with Alpha

What TGA is in plain English

TGA (Truevision Targa) is a raster image format, meaning a picture is stored as a grid of pixels, each with its own color. In spirit, TGA is a close relative of BMP: both honestly list pixels one after another and don't try anything clever with compression. But TGA can do two important things old BMP couldn't: true transparency and light lossless compression.

The format's whole philosophy is simplicity and honesty. TGA doesn't throw away detail to shrink the file (the way JPEG does), and it doesn't bury data in an elaborate structure. You open the file, read a short header, and the pixels follow — that's the entire format. Artists and game developers loved it for exactly this directness: TGA is predictable, and it's nearly impossible to "accidentally ruin the picture" with it.

Where it came from: 1984 and the Targa boards

TGA is a genuine veteran. The format was defined back in 1984 at the AT&T EPICenter division, with input from Island Graphics. Its name has two expansions, and both are about hardware: TARGA stands for Truevision Advanced Raster Graphics Adapter, and TGA for Truevision Graphics Adapter.

The format wasn't born on its own — it was the "native tongue" of specific video boards, the Targa and Vista cards. These were among the first graphics cards for the IBM PC that could display true color — millions of shades at once — at a time when ordinary PCs made do with just 16 colors. The boards were used for professional video work, which is why typical TGA image sizes matched the old TV broadcast standards of the day (NTSC and PAL).

In 1987 the team bought the technology out from AT&T and formed Truevision. Then, in 1989, version 2.0 arrived (authored by Shawn Steiner) — it added a file "tail" with metadata, a thumbnail preview, and an official format signature. We cover that tail in detail in a separate article on the internals of TGA.

How a TGA file looks inside

The structure of TGA is winningly logical. The file begins with a header that is just 18 bytes long. It records the essentials: image width and height, color depth (how many bits per pixel), the image type, and whether there is a palette. One curious detail: unlike PNG or JPEG, TGA has no "magic" signature at the start of the file — the very first byte is simply the length of an optional text description. That makes a TGA harder to recognize by its opening bytes than most formats.

Right after the header come the pixels, in the order the header specifies. No chunks, checksums, or complex trees like PNG. This directness is both TGA's strength and its weakness: it's easy to read, but it's usually heavy.

Alpha channel: transparency before PNG

This is where TGA was genuinely ahead of its time. In a 32-bit TGA, each pixel takes 4 bytes: three for color (red, green, blue) and one for the alpha channel, i.e. transparency. That gives 256 levels of transparency per pixel: from fully visible to fully invisible and everything in between.

This sounds unremarkable today, but in the 1980s and 90s it was rare. PNG, the format we think of as "the one with transparency," only appeared in 1996 — more than a decade later. So when designers and video editors needed smooth transparency — to overlay a logo or a visual effect on top of footage, say — TGA was often the only option on hand.

RLE compression: lossless and dead simple

A TGA can be saved two ways. The first is completely uncompressed (the spec calls this "type 2"): every pixel is written as-is. The second uses RLE (Run-Length Encoding, "type 10"). RLE is probably the most intuitive compression scheme there is.

The idea is simple: if identical pixels run in a row, there's no point writing each one out. Instead of "blue, blue, blue, blue, blue" the format writes "blue ×5." So on simple graphics with large flat areas — icons, logos, UI screenshots — RLE shrinks the file noticeably. On photographs, where almost no two neighbouring pixels match, there's barely any gain. The key point: RLE is lossless — the image is restored exactly.

Where TGA is used today

Despite its age, TGA is no museum piece. It still lives wherever simplicity and predictability are prized:

• Game textures. Unreal Engine and Unity read TGA happily; for years it was the standard for textures with transparency. More on that in "TGA in games and graphics".
• Video and visual effects. In video production, frames are often exported as a sequence of TGA files — reliable and lossless.
• 3D and rendering. Many 3D editors save intermediate results to TGA as a "working" format.

If you want to compare TGA with modern formats and decide when it still makes sense, see our breakdown "TGA vs PNG".

How to open and convert TGA

The everyday pain point: almost nothing opens TGA. Browsers won't display it, and the default Windows viewer won't either. The simplest fix is to convert TGA to PNG: PNG is understood by every program and browser, it's also lossless, and it too supports transparency — so both quality and the alpha channel survive.

Need the opposite — to build a TGA from an ordinary image for an engine or video edit? The reverse conversion PNG to TGA has you covered. And the full list of conversions is always on the all formats page.