Introduction: Reduce Motion Blur Using the GIMP
This Instructable helps you reduce the effects of soft motion blur you get because of camera shake. This is an experimental method developed by me, so please try out and leave comments, preferably with images.
As is evident from the quality of the photograph I hereby present, I am not a Pro. Heck. I don't even come close to my 5th grade cousin.
But I am OK with my favourite photo editor GIMP. So I tried developing a technique similar to the Unsharp Mask filter. All out of trial and error, so I don't guaranty anything. I have noticed it only reduces soft motion blur. So take a backup of the images you try this on. You have been warned.
( I found that the steps apply much better to the following images :
So here goes nothing.
Select your camera shake affected photograph and move on to the next step.
Click on the images in the following steps for a full view. Instructables seems to be cropping off the images in thumbnails, sometimes the important sections.
Step 1: Measure the Blur.
Find a suitable item/part of your image where you can 'Measure' your motion blur. That is, the angle and length. For the uninitiated, GIMP has a Measure tool. Find it. It usually looks like a divider/compass from the geometry box.
Step 2: Triplicate the Layer.
We will need the top 2 to create a sort of difference between an even more blurred version of the image (next step) and the original. Then we remove this difference from the original to get a some-what better image.
Don't ask me exactly how I came up with this. It was a bit of looking in the code of "unsharp mask" filter and a lot of trial and error.
Step 3: Add Motion Blur.
Yes. We add motion blur. If you have a slow enough computer, or large enough image on which you have run "unsharp mask" filter, you might have noticed "Blurring" before "Masking". Yes. What we do here is somewhat the same. Instead of blurring equally on all directions, we do a motion blur. Because we want to remove the motion blur.
For people who did not catch the above, it is simple : We fight motion blur with more motion blur, kind of like fighting fire with fire. Now on to what we do in this step.
In step 1, we measured the motion blur. Use this to fill the parameters for filters>blur>motion blur. Make sure you do this for the top layer. You may have to add or subtract a multiple of 90 to create the right motion blur.
Experimenting is a nice productive time pass. Do it.
Step 4: Switch Top Layer Mode to Grain Extract.
Make sure you have selected the top layer in the layers dialog, and change it's mode to grain extract. Don't panic at the result. All is fine.
Step 5: Merge the Top 2 Layers or Move to Group.
If Older than Gimp-2.8:
- Merge the top layer with the 2nd layer. Use the steps in the image to achieve it.
If Gimp-2.8 or later:
- Create a new Layer Group, and move the 2 layers to the new group.
Step 6: "Grain Merge" the Resultant Layer or Layer Group.
If older than Gimp-2.8
- Set the layer blending mode of the resultant top layer to "Grain merge".
If Gimp-2.8 or later
- Set the layer blending mode of the Layer group to "Grain Merge"
Play with Colors>Levels and the opacity of the layer/layer group to your liking. After each unblurring, if more is left, repeat. The resulting image is a bit sharper than the original.
The effect depends on different qualities of blurring, both during the shoot and step 3.
Your mileage may vary. Inputs are very much welcome.