This thesis proposes a new steganographic method called threshold based method that conserves and hides a message using least significant bits of RGB colored image. This method is based on the Run-Length of the secret message. The runs-down will be stored in the red components of the image, while the runs-up will be stored in the green components of the image. The blue components have a special use, i.e. they are used as a parity bit to ensure that the hidden message did not face any distortion or modification and to indicate the end of the hidden message. The proposed method is not robust against modification, but it can hide large amount of data inside the cover image. A comparison for the suggested method with Hide4PGP and STools has been accomplished using four image quality measurements which are Mean Square Error (MSE), Peak Signal to Noise Ratio (PSNR), Pearson Correlation Coefficient (Corr.), and Structural Content correlation (SC).