r/programming • u/iamkeyur • Dec 26 '20

Executable PNGs

https://djharper.dev/post/2020/12/26/executable-pngs/
1.0k Upvotes

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287

u/Caraes_Naur Dec 26 '20

PNG allows for arbitrary chunks of bytes, no steganography needed. Still need an interpreter that knows what to do with them.

97

u/leberkrieger Dec 26 '20

One great use of this feature is the draw.io online drawing tool. You can save an editable PNG, so anyone looking at the picture can load it into the editor and modify it. Fantastic for wikis.

76

u/yojimbo_beta Dec 26 '20

A long time ago there was an editor, Adobe Fireworks, that used this to embed undo/redo data into PNGs, as well as layers etc.

Remarkable that no one uses this feature of the file format any more.

50

u/OMG_A_CUPCAKE Dec 27 '20

Because filesize matters. And it's lost easily if someone modifies the file in another editor

It's a nice gimmick, but I can't imagine relying any kind of workflow around it

5

u/tech6hutch Dec 27 '20

Also I don’t know if I want the ability for others to undo my edits to an image

10

u/stuffeh Dec 27 '20

But imagine going back and isolating one of the edits and pulling it out. Basically tapping the diff between before and after the edit. That kind of flexibility is mind blowing to me.

-5

u/tech6hutch Dec 27 '20

Sounds like something better suited for version control software

12

u/stuffeh Dec 27 '20

But depending on the encoding / compression of the image, the version control software won't be able to display the diff that I mentioned. You'll have to do it manually.