I need to embed text in an image, research papers say HSI produces better mse and psnr therefore are better for steganography. I have RGB values(69,223,90) and its corresponding HSI is (127.223,0.458 ,0.499) I transformed I-plane 0.499 so its between 0 and 255 and got 127 as the Intensity, decreased it by one to 126(embed 0 bit). 126 was converted to the I plane normal range 0.494 and the new RGB values are red=68 green=221 blue=89. It decreased all 3 RGB values and green even more than 1. I dont understand how this is better and makes psnr better? I know the equation but say i decreased/increased the value of the intensity plane by 1 how does this affect RGB?