In this paper we propose an improved mobile phones/tablets application for robust heart rate (HR) measurement. The effectiveness and robustness over the existing approaches have been demonstrated under different distances from camera source and illumination conditions. Moreover, we compare the developed method with related commercial applications of remote heart rate measurements on mobile devices including results derived from mobile devices to electrocardiograph (ECG) and from Food and Drug Administration (FDA) approved sensors (devices). Furthermore, we present the comparison between Red (645 nm), Green (530 nm) wavelength light and Blue (470 nm) Light Reflection Photoplethysmography (PPG) for HR monitoring during motion under different conditions. We show that the green wavelength light, in general, has the potential to be a better method for monitoring HR during normal daily life. Finally, we have performed various experiments with different mobile phones and tablets. HRs were collected simultaneously from 10 subjects, ages 22 to 65, by using the 3 devices during 5-minute periods, while at rest, reading aloud under observation, and playing a video game or doing research under different distances from camera source and illumination conditions.