I have a stimulus which is a mosaic of image (a matrix of 4*7). I created a white border around the image, But I want to change the color of border into black only in the middle bottom of the border. This postion is where the participant seat in front of the image projecting on the wall, so this part of the border must be in black to hide the shaddow of the participant.
I would be thankful if any body could let me know if this can basically be done? and how?
An example of the stimulus is attached for better clarification.