Adobe Photoshop may be using the CMYK color mode, but change it to RGB. To make this change in Photoshop CS6 or CC 2018, open the file in Photoshop.

Conversely, CMYK color mode is intended for print products, so these images won't render properly on the web. Some browsers won't display your image at all, because they don't know what CMYK means.

CMYK color mode is best for artwork that will be used for printing. The CMYK color mode has fewer color variations and is more suitable for printing. CMYK color will look paler on screens.