And if I may, since I noticed the bit of blue around the light, lemme give you a trick to isolate just that red: If you're using Photoshop, go to Select > Color Range, and either select "Red" from the drop-down menu, or use the little dropper and click on the red area of the image. Increase the "fuzziness" slider value to include more than just the circle itself (if you wanted any red light reflecting elsewhere in the image for example), or decrease it to select less. Once you've done that, feather your selection a little bit (Select > Modify > Feather). I like to then make a new layer with this selection (Layer > New > Layer Via Copy), duplicate it a few times to be sure it's opaque, and then desaturate the rest of the image, leaving just the red in its own layer. Then just flatten the image and you're good to go! Anyway, hope that will be helpful to you in some way.
And if I may, since I noticed the bit of blue around the light, lemme give you a trick to isolate just that red: If you're using Photoshop, go to Select > Color Range, and either select "Red" from the drop-down menu, or use the little dropper and click on the red area of the image. Increase the "fuzziness" slider value to include more than just the circle itself (if you wanted any red light reflecting elsewhere in the image for example), or decrease it to select less. Once you've done that, feather your selection a little bit (Select > Modify > Feather). I like to then make a new layer with this selection (Layer > New > Layer Via Copy), duplicate it a few times to be sure it's opaque, and then desaturate the rest of the image, leaving just the red in its own layer. Then just flatten the image and you're good to go! Anyway, hope that will be helpful to you in some way.