Albedo: A Reflectance App 1.1

Albedo is an application specifically crafted to measure the albedo, also known as reflectance, of various surfaces. Albedo is quantified as the ratio between light reflected by a surface and the light it receives. It is essentially an indicator of the percentage of incident light reflected by a surface; for example, fresh snow boasts an albedo of approximately 90%, whereas asphalt typically exhibits an albedo of around 10%. The Albedo app is adept at assessing both the broadband albedo, covering the entire visible spectrum, and the spectral albedo across the red, green, and blue color channels of a camera.

Important: To operate Albedo effectively, users must employ an 18% photographers gray card as a reference point. These cards are readily available at photography outlets and online stores. For further information on gray cards, kindly peruse the accompanying website.

• Albedo provides a user-friendly interface that efficiently steers users through the image collection process, requiring snapshots of both a gray card and any desired surface. Once these images are captured, they can be promptly analyzed. During image analysis, the Albedo app computes the albedo of the surface relative to the RGB color channels of the camera. The gathered data is automatically stored and can be either retrieved within the Albedo app or downloaded to a computer from Albedo's designated data folder (accessible via iTunes).

How it operates:

Albedo leverages the camera as a basic light sensor (photometer). Relative light intensity can be gauged by standardizing the pixel values of the camera based on exposure. Consequently, the camera's three color channels (RGB: Red, Green, Blue) furnish insights into light intensity across distinct visible spectrum regions.

The app measures the light intensity reflected from a surface when a user captures an image thereof. This reading is normalized against ambient lighting utilizing the gray card image. The ultimate output is a nearly illumination-agnostic evaluation of surface albedo. Surface albedo stands as a pivotal metric for environmental scientists seeking to unravel how different surfaces and substances interact with light. Albedo finds widespread applicability in fields such as climatology, astronomy, and geoengineering.