JPEG conversion and transparency

Help & Support
1

the image conversion dialog allows setting transparent colour for alpha in jpegs
and I thought jpeg had been updated to support this, (not sure if its a seperate codec, jpeg2000 or jpegxl ?)
but after conversion the jpeg images do not have alpha.

image
image745×454 45.3 KB

can we have some support for the new jpeg codecs please.

2

JPEG doesn't support alpha. That option is there so you can specify a solid color to put the image on before converting to JPEG.

3

The feature request ?

4

Which codecs do you mean?

5

JPEG2000 and JPEG XL are both advanced image codecs, but they have some key differences:

JPEG2000:

  • Compression: Offers both lossy and lossless compression.
  • Quality: Known for high-quality image compression, especially for medical imaging and digital cinema.
  • Adoption: Widely used in specific industries but not as common for general web use.
  • Features: Supports alpha transparency, progressive decoding, and error resilience.

JPEG XL:

  • Compression: Also supports both lossy and lossless compression.
  • Quality: Provides better compression efficiency and quality compared to JPEG2000.
  • Adoption: Designed to be a universal replacement for many image formats, including JPEG, PNG, and GIF.
  • Features: Legacy-friendly, meaning it can transcode existing JPEG files without additional loss. It also supports alpha transparency and progressive decoding.

In summary, JPEG XL is a more modern and versatile format with better compression efficiency and broader applicability. However, JPEG2000 remains relevant in certain specialized fields. If you're looking for a future-proof, high-quality image format, JPEG XL might be the better choice.

(hmmm - asked copilot as was quicker than doing web search, but seems to be kosher :slight_smile: )

6

Opus already supports JPEG 2000.

7

I do not see it ?
image

8

It’s read only, and JPEG2000 is a failed and ridiculous format almost nothing else supports and nothing ever fully implemented.

If you want transparency, use PNG.

9

Leo is right: If you want transparency, use PNG.

There are many fake JPEG formats, "JPEG 2000" is the first one and "JPEG XL" is the last one.

The current real version is JPEG 9, and the next one will be JPEG 10, it is as simple as that.

See 33 Years JPEG: Ubiquitous Presence and Still in its Infancy, and particularly the corresponding article.

Notice that Directory Opus is mentioned as a reference application for JPEG.

JPEG 10 makes further progress as described in the article, but transparency is still not contained, maybe in JPEG 11...

Use JPEG and PNG respectively and you are well served for common usage. Avoid WebP, because it is inferior.

Regards
Guido
JPEG developer

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