You can pass XData and YData properties to imagesc() in order to control the positions of the data pixels in data coordinates. By careful choice of axes Position and axes Units properties, and using the XData and YData properties, you can control the exact number of pixels that an image will take on the display.
However:
- Be careful: XData and YData correspond to coordinates of the centers of the boundary pixels, not to the edges. You need to allow space for half a pixel relative to the coordinates given
- With high enough resolution displays, on Windows MATLAB maps 100 "pixels" to 1 inch, and on Mac MATLAB maps 72 "pixels" to 1 inch. Determining the correct adjustment for physical pixels can be a nuisance.
- data pixels cannot be different sizes when this is used. If you need data pixels to be different sizes, see warp()
... But I suspect that is not what you are talking about. I suspect what you are looking for is painting the grid. "grid on", and look at XTicks and XMinorTicks to control grid locations.
