Thumbnails color changes

Does anyone knows how to avoid the change of the colors in the images wordpress made after the uploading?

If I export an illustration in safe colors and upload (black and grey illustration), the colors of the Thumbnails change.

Left one, the mew image from wordpress, right one the original color.

I export as sRGB from adobe illustrator .

This was the first search result I found:

Yes, I read some of them. All say the same but those tutorials maybe are for jpb, because I try with a .jpg file and it works, but if I try with a .png, do not works. The colors are a litle different of the original one. A very dark gray instead of the original gray.

Regardless: this isn’t a Pressbooks issue. You are more likely to find specific answers to you problem on the WordPress forums:

Is your PNG translucent?

I know is not a PB issue, but is a situation that will afect to all the PB users if they upload a .png image.

The .png are not translucent.

I will keep searching a litle more. I did ask in WP, i´m waiting an aswer.