Low Quality with image processing using Filter image_masque

Dear community,

I have a modele I use for embedding images in the text. I have noticed the quality of the images drops really low when I try to use the |image_masque filter.

This behaviour is not due to the |image_smush filter applied.

Here is an example of an image using a JPG and overlaying a transparent PNG with logo on top using |image_masquelink.png,mode=normal :

I’m using GD2 for image processing. Selecting different image processors results in different, but always low-quality output. Example :

https://www.ursriggenbach.com/d3d239a672f98eaf7b8c6eff6ffd6935.png

Here is the code of the modele :

<img  src="[(#CHEMIN{#ENV{path}}
|image_proportions{[(#ENV{aspect}|sinon{0})]}
|image_masque{#CHEMIN{#GET{branding}},mode=normal}
|image_reduire{[(#ENV{size}|sinon{960})],*}
|image_smush|extraire_attribut{src})]
" >

My question is how do I make sure the automatic image processing is doing all actions without reducing the quality of the images ?

Kind regards,
Urs