Different steganography techniques have been presented based on RGB image as the image is considered secure cover for hidden data. Specifically, this paper presents edge-based image steganographic method using parameterised Canny edge detector that relies on embedding the secret message bits into variable LSB length of the blue colour channel of the cover image. The blue colour channel is selected because the steganography-based research showed that the visual perception of blue colour intensity is less distinct than the red and green colours. Secret message bits are embedded up to four bits of LSB which are selected by a random number generator. Additionally, as the less significant information is carried out by the LSB of each pixel so slight changes of LSB will not affect the visual quality of the cover image. The proposed algorithm was tested on a set of RGB colour images, and satisfactory results were demonstrated regarding minimum distortion in the blue colour of a pixel and visually identical original and stego image.