Digital images are the most common cover files used for steganography. This paper investigates the pros and cons of colour and grayscale versions of images when used as steganography covers. Therefore, it comparatively evaluates the performance of both grayscale and colour versions of a given cover image when they are used with a given steganography method. Moreover, this paper examines the capability and impact of using the chrominance components for data hiding. However, two steganography methods are used as test methods, JSteg and JMQT. As a result, using colour images is better than using grayscale images for data hiding. In order to increase the hiding capacity, chrominance components can be used for data hiding. However, this degrades the quality of stego images and increases the ultimate stego image size.