MATLAB: What are compile-time constant

Image Processing ToolboxMATLABmatlab codermex

Hi I want to generate a MEX file for following function

function RGB = test(I)
RGB = insertShape(I,'circle',[150 280 35],'LineWidth',5,'Color', 'green');

I am using following cmds to generate .mex file

I = imread('peppers.png');
codegen('test.m','-args',{I})

Error: '??? COLOR must be numeric for code generation'

In insertshape doc it is mentioned that. 'Color' and 'SmoothEdges' must be compile-time constants.

I dont understand this instruction.

use [0 1 0] for the color instead of 'green'

You can change the colormap to contain blue and white. Like this:

I = im2bw(imread('cameraman.tif'));
imshow(I)
colormap([0 0 1; 1 1 1]) % Blue = [0 0 1], White = [1 1 1]

There is no built-in method to convert between True Color format and RGB vector format.

However you can easily convert because both formats are basically the same, just the numerical representation is different.

To convert an RGB array to True Color format use the following code:

truecol = hex2dec(sprintf(dec2hex(255*flipdim(rgb,2))'));

To convert a True Color number to RGB vector format use the following code:

rgb = mod([truecol floor(truecol/256) floor((truecol)/256^2)],256) /255;