libpng: New version 1.6.23

[J08nY]

Updated libpng to version 1.6.27 1.6.23
Needed to fix iCCp chunk in a lot of pngs, since libpng 1.6 is more strict in this matter. See [1] [2] [3].
Projects will also need to fix their pngs if they have an incorrect iCC profile or will receive warnings like:
ERROR: _png_warn_function: iCCP: known incorrect sRGB profile
Will do a PR in the godot-docs repo about this, adding some documentation about the errors and fixing them.

fixes #3059, updates: #5248

[akien-mga]

Meh, I merged too fast and noticed too late that you made a typo in the version number :) 1.6.27 does not exist, what we have is 1.6.23.

[akien-mga]

I fixed with 9bf3ee7 the bug that made libpng warnings treated as errors; they now raise a Godot warning instead:

WARNING: _png_warn_function: iCCP: known incorrect sRGB profile
   At: drivers/png/image_loader_png.cpp:65.

[J08nY]

Oops, sorry on the version number, I guess we just have to wait for 1.6.27 and be like ha! We had that moths ago! 😃

[rgrams]

Well this is annoying. So is there a color profile that it will accept, or does everyone have to go through some rigmarole to remove the chunk for every new png?

[vnen]

@rgrams I fixed all my problems with ImageMagicks mogrify tool (just by running find . -name '*.png' -exec mogrify {} \; in my project's dir). If the profile is correct it'll accept, since not all of my project's PNGs were showing the warning.

[reduz]

I did some fixes to ScrollContainer some time ago, maybe it fixed it

On Mon, Jul 4, 2016 at 4:05 PM, George Marques notifications@github.com
wrote:

@rgrams https://github.com/rgrams I fixed all my problems with
ImageMagicks mogrify tool (just by running find . -name '*.png' -exec
mogrify {} ; in my project's dir). If the profile is correct it'll
accept, since not all of my project's PNGs were showing the warning.

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[vnen]

@reduz maybe you meant to post on #3472?

[J08nY]

@rgrams I will do a PR in godot-docs shortly, explaining the warning and will give instructions to fix PNGs on all platforms hopefully.

[rgrams]

Could the warning message be made to specify which image it's having an issue with?

[akien-mga]

Could the warning message be made to specify which image it's having an issue with?

I don't think so, at least not without modifying the libpng source code, but that's not something we should do. Those libpng16 warnings have been all over open source projects using PNGs for years, and have always been that unhelpful sadly; improving those warnings should be discussed directly upstream.

Edit: On second thought, actually we might be able to intercept the warning and mention what file triggered it, that's worth looking into.

[J08nY]

@akien-mga Hmm will look into it, afaik libpng has no knowledge of the image source file in godot, it just reads the raw data and does its job. Although something of that sort could be done in image_loader_png.cpp

[J08nY]

For everyone searching the repo for the error message:

WARNING: _png_warn_function: iCCP: known incorrect sRGB profile

Here is a guide to fixing PNGs.

[ghost]

@reduz or @J08nY please...

godot/thirdparty/libpng/png.c

Line 2350 in d463b6e

if (png_sRGB_checks[i].is_broken != 0)

Is it legal to remove this if?

                  /* Warn that this being done; this isn't even an error since
                   * the profile is perfectly valid, but it would be nice if
                   * people used the up-to-date ones.
                   */

e: Denied here, I made a request: pnggroup/libpng#163

[akien-mga]

No. We don't touch upstream sources.