The picture read from the file is generally represented by 8-bit or 24-bit binary number for each pixel.
Read in the image I=imread ('file name');
Generally, it is the uint8 matrix of mxn or the uint8 matrix of mxnx3.
Where m, n is the pixel size of the image.
If it is 8-bit data, that is, a picture with 256 colors, a 2-dimensional matrix is obtained.
The value of a pixel is represented by uint8, that is, unsigned shaped data.
If it is 8-bit data, that is, RGB true color pictures, a three-dimensional matrix is obtained.
In the third dimension, three layers of uint8, that is, unsigned plastic data, represent RGB values of pixels.
The data type mainly used for operation in matlab is double-precision floating-point number, which is double.
Double(I) forcibly converts the type of image data into double type, which is convenient for subsequent processing and calculation.