A noble method was developed for determining indoor greenery ratio through a digital camera and image analysis. Photographs with 10 different exposure compensations level were taken at indoor room using the function of “Partial color (green)” in a digital camera under varied indoor light conditions. RGB photographs were converted into Lab mode using [Image/Mode] function of Photoshop software program. The number of green pixels were calculated within 1 to 127 level (equivalent to -127 to -1 of Hunter a* value) through “Channel a” in [Histogram] function of the software. Greenery ratio was calculated by maximum green pixel number of an exposure compensation in relation to total pixel number, as maximum green pixels number would be obtained under a certain exposure compensation level when it minimizes achromatic color by partially excessive lower or higher light condition within certain area of photograph. When greenery ratio obtained from this method was compared with general greenery calculation of green area through manual selection, coefficient of determination was 0.9852, indicating appropriate greenery ratio estimating method. When applied to vertical planter of veranda and office, greenery ratio varied at 0.53~14.96%. In our experimental condition, error of the function, “Partial color” by the digital camera was within 0.013, while the error of the function, “Channel a” by the software was within 0.005.