Motion Blur Tutorial

Tutorial steps

1. This tutorial will use one of the images provided on the CDROM. This image is called lighthouse.jpg The image can be loaded using the Load Image... option in the File pull down menu. After you have selected this option, use the file requester to select the proper directory and file to be loaded. Once the image has loaded, you will see an image which shows a ship near an island with two "moons" above in the sky. We will use the motion blur on this still image to make the ship appear as though it is moving slowly, and then rapidly to the right.

2. The next step is to select the Motion Blur operation. This can be done in one of two ways. You could select the Motion Blur icon from the Motion group. This will access the Motion Blur dialog for use. You also have the option of selecting the Motion Blur option from the Motion Group area in the Operations pull down menu. The motion blur dialog consists of three controls used to specify the length, direction, and the amount of the motion blur effect. The Length control allows you to specify an actual length for the blur effect. This length is measured as a percentage of the entire area selection. For example, a setting of 100% would result in a blur that is the entire length of the area select for each pixel in the region. So, if the area select was 20 pixels across, the blur for each pixel would be 20 pixels in the specified direction. Increasing this value will give you more blur, and a decrease will give you less blur.

   The Direction Control allows you to specify the actual direction of the blur. This means that a blur can occur in any direction that you wish, not just left, right, up, or down. The direction is specified as an angle value that can range between 0 and 360 degrees, with 0 and 360 being an upwards blur. The angle is measured clockwise from vertical. This means that 90 degrees is a blur to the right, 180 is a blur down, and so on.

   The final control is the Amount specification. The amount slider allows you to set a percentage value for the overall application of the effect. For example, a setting off 50% would give you half of the total blur available to you. A setting of 100% is the maximum value, and will achieve the largest amount of the blur effect.

3. Now that you are a little more familiar with the controls, let's apply some motion blurs to the LIGHT.JPG image. For this example, you will want to select the Rectangle Area Selection Mode. This is located in the first column, second row of the Area Selection Tool Box. This allows you to select rectangular regions using the left mouse button for sizing, and the right mouse button for positioning. Place the rectangle so that it is the height of the ship, and covers from the front of the ship to off of the actual image. Placing a portion of the area selection off of the image will increase the effective area select, and will create a nicer effect. If you have not altered the default motion blur settings, the blur should occur straight up, and have a length of 50. Since we want to create the idea of motion to the right, the blur should occur to the left of the image. As you know, the direction control measures angles clockwise from vertical, therefore a blur to the left would be at 270 degrees. Set the Degrees control to read 270 degrees at this time. You will also want to select the Undo button to eliminate the unwanted test blur, and then select the Redo button in the Area Selection Tool Box to preserve the last area selection that was made. You will also need to alter the Length and Amount controls to read 35 and 45 respectively. These settings will produce a blur which is directly to the left, 35% of the area select in length, and applies about 45% of the total blur possible. Once you have set the sliders to the correct position, simply click on the LIGHT.JPG image to apply the effect. Notice that this creates a very subtle blurring effect, which may give you the impression that the ship is moving to the right.

4. Now that we have created a subtle motion blur, let's create a more dramatic effect. Begin by pressing the Undo button to erase the last motion blur. Now, set the Length to 75, and the Amount to 85. The overall effect should be a longer blur that is even more "blurry" than the previous example. You can apply this effect by simply clicking on the image. After generation is complete, you should have a more dramatic blur effect on the ship. You get the impression that the ship is moving rapidly to the right. You should undo this application, and continue to apply various Length, Direction, and Amount settings until you feel comfortable with the effect. This tutorial will not cover the use of a motion blur in an animation sequence. The motion blur operation is useful for making moving objects appear more realistic. You can use the same concepts presented in the Asterize tutorial to create a motion blur animation.

WinImages F/x Manual Version 7, Revision 5, Level B