Capture and Analysis

To capture our photos we use the DV Capture program and a Firewire to pull the frames directly from the camera.  The Firewire allows the total amount of information to be captured with no loss of information.  The images are then saved to our working drive and opened in Adode Photoshop for editing and analysis.  First is the re-sizing of the images are a must for correct data analysis.  The cameras are setup to record images at 720x480 resolution which is incorrect for our purposes.  To be able to analyze the image correctly the resolution should be 658x480, the 658 being the correct sizing to the nearest pixel.  The images (BMP.) of the same event are then layered on the program and saved as a PSD. file which we will use for analysis.  The first step is to find the conversion factor of the image.  To do this we used the ball at rest in the first images.  We use the ruler function in Photoshop and calculated the diameter in pixels of the ball at four different angles.  These values were averaged together to get the diameter of the ball.  In the real world we measured the diameter of the ball using a similar method and calculated the diameter, in meters, of the ball.  To find the conversion factor we divided meters by pixels for each event (PSD file).  To measure the distance of any moving object on our captured images we used the ruler function in Adobe.  We measured the distance in pixels between the each frame of movement by taking the horizontal and vertical elevation of the two points and using the Pythagorean theorem to find the distance traveled on the image.  Then using the conversion factor of that file we then find the actual distance traveled in the real world.  The interval of the successive image is then recorded (in seconds) and the average velocity of the object can be ascertained when the entire set of frames is analyzed.