assigning colour to a block

I have a code below

clc
clear all
grayImage = imread('cameraman.tif');
[rows columns numberOfColorBands] = size(grayImage);
figure;
subplot(2, 2, 1);
imshow(grayImage, []);
title('Original Grayscale Image', 'FontSize', 6);
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);

blockSizeR =64;
blockSizeC =64;

wholeBlockRows = floor(rows / blockSizeR);
wholeBlockCols = floor(columns / blockSizeC);

image3d = zeros(wholeBlockRows, wholeBlockCols, 3);

sliceNumber = 1;
k=1:16;
for row = 1 : blockSizeR : rows
    for col = 1 : blockSizeC : columns
        row1 = row;
        row2 = row1 + blockSizeR - 1;
        row2 = min(rows, row2);
        col1 = col;
        col2 = col1 + blockSizeC - 1;
        col2 = min(columns, col2);

          oneBlock = grayImage(row1:row2, col1:col2);

          subplot(4, 4, sliceNumber);
          imshow(oneBlock);

          caption = sprintf('Block #%d of 4', sliceNumber);
          title(caption, 'FontSize', 8);

          S{sliceNumber}=mean(mean(oneBlock)
          sliceNumber = sliceNumber + 1;
      end
  end

here i have stored the mean value for all blocks in variable S

now i want to colour blocks in red colour which are having mean value greater than 160

plz help