Blockproc handle function problem

Hello i have a question about using blockproc i have create this code, its a simple blockproc usage i took this from example file :

% read image
awal = imread('h.jpg');
% global threshold
global_thres = graythresh(awal);
% callback function
fun=@(block_struct)...
  im2bw(block_struct.data,graythresh(block_struct.data));
% partition
info_gambar = imfinfo('h.jpg');
tinggi = info_gambar.Height/5;
lebar = info_gambar.Width/5;
I2 = blockproc(awal,[tinggi lebar],fun);
figure;
imshow(awal);
figure;
imshow(I2,[]);

in this part of code i know that we can set a custom callback function for each block created by blockproc, but if i use this code i cant add an if else condition, i want to use if else condition to determine threshold method for each block. this is a pseudocode i want to achieve

if global_threshold > then otsu local threshold on block
use otsu threshold
else 
use other threshold method
end

is there a clue for me to do this ? what i have to do with the code, i am new to matlab and maybe the solution is a kind of very basic things on matlab, any answers will help.

Thank you Regards, Putra