Only PNG supports transparency, is that true?

Question

I found JPG does not support transparency, the alpha value is always 255. I am wondering only png supports transparency?

Easygoing

There is a bunch of formats supporting transparency, just JPEG isn't one of 'em... – Anyhow

faqs.org/faqs/jpeg-faq/part1/section-12.html – Phillisphilly

TGA targa i think has alpha channel. pic formats and bit depths are amazing complex. rgba argb in all combinations for 16 to 32 bit – Garrettgarrick

Answer 1

• png-32 supports different levels of transparency. Each pixel can have an opacity between 0 and 255, with 0 as completely transparent.

• png-24 supports setting one color as fully transparent. Everything else will be opaque.

• gif uses a color palette. You can specify that one color in the palette is fully transparent.

• png-8 also uses a color palette but each color in the palette has its own opacity value, so it supports varying levels of transparency too.

• jpg does not support transparency.

Erechtheum

This is not correct. Paletted PNG-8 supports varying levels of transparency (see pngquant). Only Photoshop and GIMP don't, so you need better tools for this (e.g. Fireworks or the aforementioned pngquant). – Po

And what about bitmap images? – Albano

PNG-24 supports only GIF-like transparency (one color is specified to be the transparent color and it is fully transparent). PNG-32 supports different levels of transparency via the alpha channel, in which each pixel can have an opacity between 0 and 255. There may be some applications that erroneously refer to PNG32 files as "PNG-24". – Principe

Answer 2

JPEG 2000 supports full transparency. See JPEG 2000 Side channel spatial information.

Agnola

JPEG2000 is a new file format, not an extension of the original JPEG format. – Mintamintage

Not to be confused with the .JPG file format discussed in the question. JPEG 2000 is .jp2 – Roseroseann

Answer 3

JPEG XR (not the same as JPEG 2000) also supports transparency.
However it is not a useful format for the web as only Internet Explorer and Edge support it.

WebP is another emerging image format with support for transparency.
However, Internet Explorer lacks support for it.

Rohn

Answer 4

From Transparency (graphic) - Wikipedia:

Raster file formats that support transparency include GIF, PNG, BMP, TIFF, TGA and JPEG 2000, through either a transparent color or an alpha channel.

Autobahn