Covert the images to sRGB color gamut, that's standard for image color processing in most internet browsers.
If you edit an image in Photoshop or render it on your color proofed monitor then it will have monitor profile embedded (or adobe RGB if it's coming from digital camera), keep in mind these are wider color spaces to work in, if you display these images in a more narrow color space like sRGB then they will get over saturated and darker because of gamma mismatches.
So keep in mind to convert working color spaces to lower sRGB standard for net and adobe RGB for print.
You can use "color management" keywords to find more info on the subject.
There are many programs that can convert/add color profiles, for example Photoshop.
In Photoshop you can use convert to profile option.
Some info here (https://imageoptim.com/color-profiles.html)
And a tutorial here (https://www.youtube.com/watch?v=rpdBXMt2Mms)
Video is old but still valid.