Re: RGB colorspace question

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The most likely cause of the difference is if the PNG has an embedded ICC
CMS profile, or is marked to be in an unusual colorspace.  Perhaps
ImageMagick is applying a colorspace transformation.

Try doing

convert infile -strip -colorspace rgb foo.txt

So in this case, the input file does matter, and the versions of the
software do matter since different versions of ImageMagick work differently=
.

Bob

On Fri, Jan 5, 2024 at 4:13=E2=80=AFPM Michael Orlitzky <[email protected]=
om>
wrote:

> While working on
>
>   https://github.com/gap-packages/hap/issues/115
>
> I noticed that,
>
>   convert foo.png -colorspace RGB foo.txt
>
> produces different results with ImageMagick vs. GraphicsMagick. For
> example,
>
>   $ head -n2 foo-im-rgb.txt
>   # ImageMagick pixel enumeration: 640,480,0,255,rgb
>   0,0: (220,110,7)  #DC6F07  rgb(86.3157%,43.415%,2.84276%)
>
>   $ head -n2 foo-gm-rgb.txt
>   0,0: (239,176, 47) #EFB02F
>   1,0: (239,176, 47) #EFB02F
>
> (If you want the source image, I'm happy to provide it, but I don't
> think this is at all tricky to reproduce.)
>
> I won't embarrass myself by speculating. Does anyone know what's going
> on with the different colors?
>
>
>
> _______________________________________________
> Graphicsmagick-help mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/graphicsmagick-help
>

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<div dir=3D"ltr"><div>The most likely cause of the difference is if the PNG=
 has an embedded ICC CMS profile, or is marked to be in an unusual colorspa=
ce.=C2=A0 Perhaps ImageMagick is applying a colorspace transformation.<br><=
/div><div><br></div><div>Try doing</div><div><br></div><div>convert infile =
-strip -colorspace rgb foo.txt</div><div><br></div><div>So in this case, th=
e input file does matter, and the versions of the software do matter since =
different versions of ImageMagick work differently.<br></div><div><br></div=
><div>Bob<br></div></div><br><div class=3D"gmail_quote"><div dir=3D"ltr" cl=
ass=3D"gmail_attr">On Fri, Jan 5, 2024 at 4:13=E2=80=AFPM Michael Orlitzky =
&lt;<a href=3D"mailto:[email protected]">[email protected]</a>&gt; wr=
ote:<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px=
 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">While worki=
ng on<br>
<br>
=C2=A0 <a href=3D"https://github.com/gap-packages/hap/issues/115" rel=3D"no=
referrer" target=3D"_blank">https://github.com/gap-packages/hap/issues/115<=
/a><br>
<br>
I noticed that,<br>
<br>
=C2=A0 convert foo.png -colorspace RGB foo.txt<br>
<br>
produces different results with ImageMagick vs. GraphicsMagick. For<br>
example,<br>
<br>
=C2=A0 $ head -n2 foo-im-rgb.txt<br>
=C2=A0 # ImageMagick pixel enumeration: 640,480,0,255,rgb<br>
=C2=A0 0,0: (220,110,7)=C2=A0 #DC6F07=C2=A0 rgb(86.3157%,43.415%,2.84276%)<=
br>
<br>
=C2=A0 $ head -n2 foo-gm-rgb.txt<br>
=C2=A0 0,0: (239,176, 47) #EFB02F<br>
=C2=A0 1,0: (239,176, 47) #EFB02F<br>
<br>
(If you want the source image, I&#39;m happy to provide it, but I don&#39;t=
<br>
think this is at all tricky to reproduce.)<br>
<br>
I won&#39;t embarrass myself by speculating. Does anyone know what&#39;s go=
ing<br>
on with the different colors?<br>
<br>
<br>
<br>
_______________________________________________<br>
Graphicsmagick-help mailing list<br>
<a href=3D"mailto:[email protected]" target=3D"_bla=
nk">[email protected]</a><br>
<a href=3D"https://lists.sourceforge.net/lists/listinfo/graphicsmagick-help=
" rel=3D"noreferrer" target=3D"_blank">https://lists.sourceforge.net/lists/=
listinfo/graphicsmagick-help</a><br>
</blockquote></div>

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