Question

Or say does 1 denotes white for an RGB image?

I have this question because of this answer:

How to convert a grayscale matrix to an RGB matrix in MATLAB?

Can someone clarify it?

Answer 1

Image data in MATLAB can be stored as different data types. The type of image as well as the data type it is stored as will determine what constitutes the color “white”:

• A grayscale image matrix (which has one data value per pixel) can be any one of the following data types: uint8, uint16, int16, single, or double. From the documentation:

  For a matrix of class single or
  double, using the default grayscale
  colormap, the intensity 0 represents
  black and the intensity 1 represents
  white. For a matrix of type uint8,
  uint16, or int16, the intensity
  intmin(class(I)) represents black and
  the intensity intmax(class(I))
  represents white.

• An RGB image matrix (which has three data values per pixel: red, green, and blue) can be any one of the following data types: uint8, uint16, single, or double. From the documentation:

  In a truecolor array of class single
  or double, each color component is a
  value between 0 and 1. A pixel whose
  color components are (0,0,0) is
  displayed as black, and a pixel whose
  color components are (1,1,1) is
  displayed as white.