Subsampling is a commonly used technique for modern image and video compression. Existing image and video standards such as JPEG, MPEG, and H.264 provide support for uniform chroma subsampling. This paper presents an algorithm that uses adaptive luma subsampling based on a combination of three perceptually significant image characteristics (texture, edges, and brightness) to complement uniform chroma subsampling. The algorithm is computationally efficient, simple to implement, and easy to integrate into existing standards. Experimental results show that the introduction of adaptive luma subsampling improves image quality both quantitatively and qualitatively when compared with the sole use of uniform chroma subsampling.