Confused about the RGB colour coding

Hello, I wonder if the Matlab RGB color index is just the usual RGB index divided by 255??? The default RGB color list is as follows in Matlab:

For example green is [0 1 0] the default RGB coding in the Colour software like Photoshop is [0 255 0] so do I just divide the color coding in Photoshop RGB format by 255 to arrive at the Matlab RGB color code?

I wonder if there is an inbuilt function like that... Thanks! D

Answer 1

[Jan]

If you store the RGB values as a [X, Y, 3] DOUBLE array, the values are going form 0 to 1. If you use an UINT8 array, the values are in the interval [0, 255], as in many other applications (Photoshop, color-pickers, HTML, etc).

A simple conversion:

RGB_double = rand(200, 100, 3);
RGB_uint8  = uint8(RGB * 255 + 0.5);

The 0.5 cares for the same weights of the UINT8(0) and UINT8(255) bins.

See also: im2double and im2uint8.

[Dima]

THANK YOU FOR YOUR ANSWER....I wonder if there is a function that can transform the usual format in the Photoshop for example to the Matlab format? for example I have this colour in Photoshop

0, 204, 255 which corresponds to [0 0.8 1] in Matlab.....do I just divide the vector manually typed from Photoshop by 255 to arrive at the Matlab color?

thanks!))

[Image Analyst]

Yes. Dividing by 255 is fine. Or by intmax('uint16') if you're using 16 bit numbers.

[Walter Roberson]

im2double() does the type-checking and divides by the appropriate scaling factor.