GPL-3.0&#39;s &quot;Open-Sourceness&quot;, Images and Image Formats
<p>I took an SVG image from a set which is distributed under GPL-3.0 and used it as (a large) part of an icon I made to a software of mine, which is also distributed under GPL-3.0. So far, everything is fine, I suppose. I am, however, intending to distribute this icon I made (together with my whole software) as a PNG image, for it is smaller and I'm not used to Create SVG images. Is redistributing this altered version of the SVG image as a PNG an infringement of the following GPL-3.0's excerpt:</p>

<blockquote>
  <p>if you distribute copies of such a program, whether
  gratis or for a fee, you must pass on to the recipients the same
  freedoms that you received. <strong>You must make sure that they, too, receive
  or can get the source code</strong>. And you must show them these terms so they
  know their rights.`</p>
</blockquote>

<p>given that an SVG, like a script, comes with the "source code", as it IS the very source code itself, while a PNG "hides" this, being binary non-readable data? </p>

<p>The clear question is what constitutes the "source code" of an image in PNG format. Since such images <strong>can</strong> be modified, it could sensibly be argued that they are already in source code form, and no other form need be distributed with the. Since at least some people find an image in SVG form easier to modify, it could be argued that that form is the "source code", and must be included with any distribution, or offered.</p>

<p>If the OP does the modifications in SVG format, and only then converts to SVG format, that suggests that the SVG format serves as the source code.</p>

<p>I could not find any case law on this point, one way or the other.</p>

<p>It would probably be safer to provide an SVG form along with the PNG form of the logo. Clearly that would be in compliance with the GPL. Howe much extra trouble and expense, if any, it would require, the OP would have to judge. I think that a suit demanding an SVG form would be unlikely.</p>

<p>I don't suppose the logo would be "a program" in that case. I would assume almost all original PNG logos found in GPLv3 software have been created in editors that have features that are non-recoverable from the logo after it's been exported as PNG (for example, layers and paths in GIMP or Photoshop) and releasing that PNG alongside a program under GPLv3 won't violate it.</p>

<p>From a technical point of view, you can add additional data to any .png file. So you could add a TEXT chunk containing the GPL license, and an SVG chunk containing the original SVG image. You should look for example at the Wikipedia page how to do this (both would be marked as non-standard items because they are not part of the PNG standard, ancillary items because the PNG file can be opened and displayed without the software understanding these changes, and "safe to copy" because they can be copied safely by software that doesn't understand them. So if I modified your PNG image, my editor should leave all this information intact.) </p>

<p>Now it is up to you to decide if you have done your duty from a moral point of view, if you can be successfully sued for copyright infringement, and if you are likely to be sued (important because being sued is costly and inconvenient, even if you win the case). </p>

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