The function imread can read an image file, for illustration a JPEG (.jpg) file. The function reads color images into a 3-dimensional matrix.
>> myimage1 = imread('Fishing_1.JPG');
1536 2048 3
In this situation, the image is presented as true color matrix. This points that the image consists 1536 × 2048 pixels. The image can be altered by manipulating the numbers in the matrix. For illustration, multiplying each number by 0.75 will result in a range of values from 0 to 191 rather than from 0 to 255.
>> dimmer = 0.75*myimage1;