Why does my transparent logo have a white background now?

It was probably saved as JPG, which cannot store transparency, so the transparent areas were filled with white. Re-export from the original as PNG or WebP.

Does transparency increase file size?

The alpha channel adds some data, so a transparent PNG is usually larger than the same image without alpha. WebP and AVIF keep transparency at smaller sizes.

Do these tools upload my images?

No. Utilumo's image tools decode, edit, and export pictures inside the browser tab. The files are never uploaded or stored on a server.

Explainer1 min readUpdated June 29, 2026

What is an alpha channel (image transparency)?

Short answer

An alpha channel is extra per-pixel data that stores transparency: how much of the background shows through. It is what gives a logo a see-through background instead of a white box. PNG, WebP, and AVIF support it; JPG does not.

A fourth channel for transparency

A color pixel has red, green, and blue values. The alpha channel adds a fourth value for opacity: 0 is fully transparent, the maximum is fully opaque, and values in between are partly see-through. That is the A in RGBA. See HEX, RGB, and HSL color codes.

Which formats support it

PNG — full alpha transparency, the usual choice for logos and icons
WebP and AVIF — support transparency with smaller files
GIF — only fully transparent or fully opaque pixels, no soft edges
JPG — no transparency at all

Converting to JPG loses transparencyBecause JPG has no alpha channel, exporting a transparent image to JPG fills the see-through areas with a solid color, usually white. Use PNG or WebP to keep transparency.

Try it: Image ConverterConvert between PNG, WebP, and JPG locally, keeping or flattening transparency.Open tool

Soft edges and halos

Partial alpha is what makes anti-aliased edges look smooth. If a transparent image was flattened against the wrong background color, you can get a faint halo around the edges, which is a sign it was exported onto a mismatched background.