1. A method for real-time estimating of an image quality, for use with a device that comprises in a single enclosure a digital camera module or functionality that comprises an optical lens for focusing received light from a scene and an image sensor coupled to the optical lens for capturing an image of the scene; a motion or location sensor for sensing the device motion; and a processor coupled to the image sensor and to the digital camera for receiving data therefrom, the method by the processor comprising: Obtaining a first value (QI1) responsive to the device motion from the motion or location sensor; estimating a first weight (c1) associated with the first; obtaining a second value (QI2) associated with the digital camera; estimating a second weight (c2) associated with the second value; analyzing the captured image for detecting or recognizing one or more objects in, or one or more characteristics of, the image; obtaining a third value (QI3) associated with the analysis; estimating a third weight (c3) associated with the third value; calculating a total value according to, or based on, the first value (QI1) weighted according to first weight (c1), the second value (QI2) weighted according to second weight (c2), the third value (QI3) weighted according to third weight (c3); comparing the total value to a threshold; determining whether the total value is higher than, or below than, the threshold; and acting in response to the determining.