Updated March 2012.
- Software used: Photoshop CS4
- Time taken: 45 minutes.
- Try this tutorial for yourself by clicking on the image to the right to download a high resolution image.
Adding your own motion blur is useful when you haven't quite got the right kind of drama in your original action shot.
With the above motorcross shot I was careful in getting the exposure right and ensuring the necessary focus point was on the bike as it passed. In doing this I'd failed to notice that the shutter speed was too high and it's resulted in a super sharp shot, but one that looks static and lifeless. However, using a few layers and Photoshop's Motion Blur filter we can bring back the essence of the day - speed.
Step 1: Duplicate The Background Layer Twice
Duplicate the layer by dragging the background layer icon over the New Layer icon or, from the menu, Layer>Duplicate Layer. Repeat this so you have three layers: Background, Background copy and Background copy 2.
Step 2: Make A Selection Around The Bike
Use your preferred tool to select the bike and rider. I used the Polygonal lasso tool at high magnification. You may prefer to use the Pen tool or the magic wand. Make the selection exclude the grass areas in between the chassis and the gap in between the rider and the bike. Don't worry about the grass and dirt showing through the wheels, we will look at these later. Use the +/- selection options in the tool bar to add or detract from the selection. Try to make it as accurate as possible to save time later, but be aware that any mistakes you make now can be rectified later as we are going to use a pixel mask in the next step.
Step 3: Create A Pixel Mask
Add a pixel mask to your Background copy 2 layer. (If you're using older versions of Photoshop do this step by adding a layer mask.) With this layer selected go to Window > Masks to open the Mask palette and click on the circle in a square icon (top right). This adds a black and white square at the side of the layer icon.
At this stage your photo won't look any different. If you've done it right you will see a white shape has appeared in the mask where the bike is. In the illustration below I've turned off the two lower layers so you can see what you should now have. To do this click on the eye icon of the layer you want visible while holding down the alt key. The black area on the mask is what will show through from the layers below. As I've turned them off you can see transparency (the white and grey checkered grid).
Step 4: Remove The Selection
Click ctrl+D to undo the selection and reactivate the layers if you turned them off in the last step.
Step 5: Add Motion Blur To The Background Layer
Select the background layer and add some heavy motion blur: Filter > Blur > Motion Blur.
In the pop up box, set the angle to match the direction of your subject. In this case it's -9 as the bike is travelling down a slight incline. Click on the eye icon of the background layer while holding down the alt key. Make sure the Preview box is ticked so you can see the effect on your main image and adjust the distance slider so you get a good heavy blur. Make sure you maintain some detail in the streaks or it will look unnatural. In this example 150 pixels was set. Click OK.
Step 6: Add Motion Blur To The Background Copy Layer
Repeat the same blur process from step 5 on the Background copy layer, this time with less motion so a Distance of around 80 pixels.
Step 7: Add A Layer Mask To The Background Copy
Turn all the layers back on. What you should see is a slight blur to the background with a blurry outline around the rider and his bike. This is because the top layer mask is letting the slightly blurred layer below show through in all the black areas. Now we will add a gradient mask on the background copy layer to let some of the really blurred background layer come through.
With the background copy layer selected go to Layer > Layer Mask > Reveal All. This adds a white square at the side of the layer icon. Click on this square.
Step 8: Select The Gradient Tool
Select the gradient tool. Make sure black and white are the foreground and background colours. Select foreground to transparent in the gradient options and the linear gradient option.
Step 9: Draw A Gradient Over The Mask
Click on the photo in the left area, hold the mouse down and drag to the right of the subject following the same angle you applied the blur at (Path, length and direction indicated by the red arrow). Let go of the mouse and the gradient will be applied over the mask, revealing the more blurred background layer on the left at the rear of the bike. This keeps the blur at the front weaker and makes the action look more dynamic.
If you feel the blur on the background layer is too defined, like in this case where the helmet and rider's back is prominent, you can add some more blur by clicking on the background layer and repeating Step 5. Experiment until it looks right. I've redone that stage again here adding another 200 pixels distance.
Step 10: Select And Transform The Wheels
Our final step is to make the wheels spin. Using the Elliptical Marquee tool and the + selection, make a selection around each wheel (you can do one at a time if you prefer). And copy (ctrl+c) and paste (ctrl+v) onto a new layer. Turn off the other layers and select Edit>Transform>Distort. Then drag the rectangle corners around until both wheels are as close to perfect circles as you can get. We do this so the spin will look more realistic and in the correct persepctive.
Step 11: Make The Wheels Spin
Use the Elliptical Marquee tool to select the left wheel. Go to Filter>Blur>Radial Blur and set Blur Method to Spin and Quality to Good. Drag the Amount slider to around 20 and click ok. Repeat this with the right-hand wheel by making the selection and clicking ctrl+F to apply the same blur.
Step 12: Realign The Wheels With The Layer Below
Turn the other layers back on and set the new wheels layer to 60% opacity so you can see the layer below through the wheels layer. Select Edit>Transform>Distort and use the corner points to drag the wheels back and align them perfectly over the background as they used to be.
Step 13: Erase And Tidy Up Around Wheels
Set the opacity of the wheel layer back up to 100%. Add a layer mask (Layer>Layer Mask>Reveal all) and with the layer mask active paint out the sharp background around the wheels using the eraser brush. If you erase too much you can paint back by switching between erase and paint using the X key. Brush along the frame, shock absorbers, and rider's boot to make them sharp again.
Step 14: Flatten The Layers And Make Final Adjustments
Flatten the image and use the clone and heal tool to make minor tweaks to any blurred/sharp bits around the wheels. You may also want to apply a motion blur on the whole thing now and use the History brush to bring back sharp areas or set to screen mode and reduce opacity. This, along with the previous steps, certainly gives a feeling of action. In my example I lightened the shot so it looks like it's taken with second curtain fill flash.