Gifs vs Jpgs

I just learned something today.  The .gif format sometimes changes the color of an image.  I just posted a .gif of a sketch I did  this morning and saw that the reds were dulled down.  I looked at the jpg of the same sketch and it retained the reds.  Something to consider when posting sketches.
Here are the two versions.

JPG Colors are more true.

GIF format dulled down the red and yellow colors.