[Gambas-user] Image.Save resp. Picture.Save Method

[Fabien Bodard]

My answer will be fast ... I don't know :-)... but I suspect you're
true about the mapping

Le dim. 5 sept. 2021 à 11:44, Claus Dietrich
<claus.dietrich at freenet.de> a écrit :
>
> Hi
>
> The Image.Save resp. Picture.Save method in Gambas is using an optional "quality" parameter, which according to
>
> the documentation is applied when saving the bitmap in the JPG and PNG file format.
>
> The PNG format however is normally using a lossless compression. That means, that the "quality" of compressed
>
> PNGs doesn't change, which also is my practical experience in Gambas. According to my research the
>
> used gdk-pixbuf library is using a "compression" parameter for PNG and "quality" parameter for jpg which makes
>
> more sense to me.
>
> Further a JPG-compression is typically provided by a 0-100 percentage-parameter, while the PNG compression
>
> is normally selected by a value between 0 and 9 where each value refers to different compression method.
>
> This raises two questions:
>
> 1.    Why is the optional saving parameter called "quality"?
>
> 2.    Is there a special mapping between the percentage value and the PNG compression methods?
>
> All of you have a good Sunday
>
> Claus
>
>
>
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-- 
Fabien Bodard