Click thumbnails for full-size images (768x100 px, 70 - 180 kB each).
Download and unzip the ZIP archive below and unzip into a directory of your choice. Run the Ring.bat file - this will open a command prompt window and then the Java application in its own window.
1) Load the image: Press the load button and select a Retcam image file (24 bit RGB bitmap, 640x480) to examine.
2) Set the radius: Select the desired radius of the circle to analyse using the combo box below the load button.
3) Select the Circle Origin: Right-click on the image at the centre of the optic disk - a circle centred on this point is drawn. You can adjust the radius of this circle in the combo box below the load button. If you adjust the radius before placing the circle the red green and blue values for 360 pixels around the circumference of the circle will be displayed in the area below the image. If you adjust the radius after selecting the circle's origin then you will have to click the update button next to the chart area.
4) Mark points of Interest: Use the left and right arrow keys to move the white point around the circumference of the circle. When you wish to mark a point of interest press the spacebar -prwessing the spacebar when over an existing marked point deletes the marker. A grey line is drawn on the updated charts below to identify each point of interest - e.g. vessel crossing points.
5) Save the results: When you are satisfied with the results the pixel data can be saved by clicking the save button - this will generate a tab-delimited text file of pixel vales at one degree intervals around the perimeter of the circle along with a column marking the points you have selected. The coordinates of the centre of the circle and its radius setting are also saved and the file can be opened in MS excel for plotting and further analysis. Generally the green channel gives the best contrast between vessels and background.
Download a ZIP archive containing the .class file for this application along with instructions for installation and operation, example image and the invoking .bat file.