Why colors change after saving an image as Jpg?

[ilgk48]

Hi to all,
the question is simple anf direct:

I have an image (a simple square box) filled with RGB(255,0,0), to say completely red.
The color space is sRGB.
I save it as jpg with this options:

I do not run Optimizer

Now I reopen it (the dialog box says the ICC is none ... boh!):

I look at it and PSP says that the color is (254,0,0)!!

Please, why and there occurs this transformation? I did some test without any result.
Thank you.

PS. In 2015 there was a post "JPEG Optimizer Removes Embedded sRGB Color Profile" that in some way is related to my question: at that time the author seemed disappointed with PSP.

[Jean-Luc]

It is perhaps the normal behaviour of the JPG compression algorithm which is a lossy format.

If you do the same manipulation in Windows Paint, you will get the same 254 0 0 result when saving in JPG.

In Painter Essentials 7, when saving in JPG with sRGB IEC61966-2-1 black scaled profile incorporated, I get 255 0 0. When saving without this profile, I get 254 0 0.

Saving with PSP in PNG format gives always 255 0 0.

[ilgk48]

Thank you very much, Jean Luc.
I'm thinking to use PNG from now