Jason - you can change the y-ticks on the axes as follows
% create the image
h = imagesc(stdmap,[100,500]);
% get the handle to the parent axes
hAxes = get(h,'Parent');
% create the new y-ticks at the integer positions from 1 to
% the maximum integer
newYTicks = 1:floor(max(get(hAxes,'YTick')));
% set the ticks and the labels for the y-axis
set(hAxes,'YTick',newYTicks,'YTickLabel',num2str(newYTicks))
We use the handle of the image, h, to get the handle to the parent axes, hAxes. Then we obtain the positions of the YTick tick marks (along the y-axis) and convert to newYTicks which will just be the integers from 1 to the (integer once floored) maximum tick position. Then we set the tick positions and labels.
As for adding the actual values on to the plot, do you mean into the figure itself at each "square"? I think you would have to use text objects for that.
