Curved Motion Blur

S
Posted By
Sean
Dec 12, 2003
Views
2250
Replies
8
Status
Closed
Lets say I have an image of a knight astride a horse holding out and apparently swinging a sword. Now suppose this image was created on a bright sunny day and there is absolutely no motion blur in the image.

Next suppose you want add a small amount motion blur to the sword and arm holding it and having some curvature to the blur . I know I can do this by:

– Extracting the sword
– Placing it in a new image, such that it is centered horizontally and perfectly vertical touching the top and bottom of the frame. The size of this image is dependent upon how much curvature you want the polar coordinates transformation to create.
– Doubling the image size in pixels via resampling.
– Applying a horizontal motion blur to it.
– Applying the polar coordinates transform to the blur. – Copying pasting, rotating, and properly placing the blur into the original image.
– Use a layer mask to get thing just right.

So now if you are still with me, then I will get to my question. Do you know of a more efficient way of doing this? This is not engineering so the curvature can be arbitrary so long as it looks okay. The requirement is that the blur follow a smooth curve and that the blur matches the object in coloration exactly.

Any insight would be appreciated.

enjoy your day,

Sean

"In the End, we will remember not the words of our enemies, but the silence of our friends."

– Martin Luther King Jr. (1929-1968)

Redesigned – Last Updated 15 October 2003
Photo Archive @ http://www.tearnet.com/Sean
Related Tags
blur curve motion

Must-have mockup pack for every graphic designer 🔥🔥🔥

Easy-to-use drag-n-drop Photoshop scene creator with more than 2800 items.

L
l
Dec 12, 2003
In article ,
Sean wrote:

engineering so the curvature can be arbitrary so long as it looks okay. The requirement is that the blur follow a smooth curve and that the blur matches the object in coloration exactly.

Try creating a curved path and stroking that using the Smudge tool. Maybe add a fade value in the Brushes dialog as well.

..lauri
N
nettle
Dec 12, 2003
On Fri, 12 Dec 2003, Sean wrote:

Lets say I have an image of a knight astride a horse holding out and apparently swinging a sword. Now suppose this image was created on a bright sunny day and there is absolutely no motion blur in the image.
Next suppose you want add a small amount motion blur to the sword and arm holding it and having some curvature to the blur .

<snip>

So now if you are still with me, then I will get to my question. Do you know of a more efficient way of doing this? This is not engineering so the curvature can be arbitrary so long as it looks okay. The requirement is that the blur follow a smooth curve and that the blur matches the object in coloration exactly.

Don’t know if this is necessarily more efficient, but you can try this:
Create a selection of the arm and sword. Copy and paste to new layer. Use free transform to rotate copy slightly (move rotation point to shoulder or elbow joint). Use rectangular marguee to select around arm and sword (will allow better control of blur effect). Use radial blur and choose spin. Move pattern inside the control box so that the spin originates from the corner of your selection where your arm joint sits. Blur around 10-15, depending on effect desired. Use soft eraser to blend in rotation point.

You can also create more than one layer with slightly different rotation and blur amounts to create different effects. This effect goes pretty quickly once you get a feel for it. I just tried it on a horse leg and it only took me a couple minutes. Check out this image: http://www.tstonramp.com/~niemand/pspics/radialblur.jpg
Quickly done, but you can get the idea of the effect.

—
nettle
J
JJS
Dec 12, 2003
Good suggestions so far.

One short and easy tip: Remember that when rotating (image-transform-rotate) or applying radial blur (filter-blur-radial), you can set the pivot point. If you move the pivot point closer to the hilt or handle of the sword, it will have a more realistic blurred path. You can add perspective to the merged sword-blur with Image-Transform. Then do the luminance things.
S
Sean
Dec 14, 2003
On Fri, 12 Dec 2003 11:54:18 +0200, l
reverently intoned up the aether:

In article ,
Sean wrote:

engineering so the curvature can be arbitrary so long as it looks okay. The requirement is that the blur follow a smooth curve and that the blur matches the object in coloration exactly.

Try creating a curved path and stroking that using the Smudge tool. Maybe add a fade value in the Brushes dialog as well.

.lauri

Thanks Lauri. That is something I did not know how to do and did not know how to think about. It seems elegant and would work well in more complex situations. It did require a very carefully places path start and creating a custom brush to get the smudge tool to do the job. The only downside is this solution is very CPU intensive. I will probably hold off exploring it extensively until I have a faster computer due to the size of images I am working with.

enjoy,

Sean :o)

"In the End, we will remember not the words of our enemies, but the silence of our friends."

– Martin Luther King Jr. (1929-1968)

Redesigned – Last Updated 15 October 2003
Photo Archive @ http://www.tearnet.com/Sean
S
Sean
Dec 14, 2003
Thank you Nettle. The result is roughly the same. The set of operations is simpler. But I am not quite as fond of the character of the blur used. But alternate ways of achieving similar ends is what I was looking for and you provided such.

enjoy, :o)

Sean

"In the End, we will remember not the words of our enemies, but the silence of our friends."

– Martin Luther King Jr. (1929-1968)

Redesigned – Last Updated 15 October 2003
Photo Archive @ http://www.tearnet.com/Sean
S
Sean
Dec 14, 2003
On Fri, 12 Dec 2003 11:52:12 -0600, "jjs"
reverently intoned up the aether:

rt and easy tip: Remember that when rotating (image-transform-rotate) or applying radial blur (filter-blur-radial), you can set the pivot point. If you move the pivot point closer to the hilt or handle of the sword, it will have a more realistic blurred path. You can add perspective to the merged sword-blur with Image-Transform. Then do the luminance things.

Thanks.

enjoy,

Sean

"In the End, we will remember not the words of our enemies, but the silence of our friends."

– Martin Luther King Jr. (1929-1968)

Redesigned – Last Updated 15 October 2003
Photo Archive @ http://www.tearnet.com/Sean
MA
mohamed_al_dabbagh
Dec 14, 2003
Hi Sean!

I am not sure what kind of curved motion blur you ask for. However, I use some procedure that you might find it helpful in some cases, when you want a motion blur with curved streak and vanishing end point. I do the following:

1- Duplicate the layer of the object to be motion blurred (isolate the object if necessary by extracting it alone before duplication).

2- On the lower layer, use motion blur with sufficient number of pixels and the best suited angle of the streak. Apply Free Transform making the required perspective distort and streching the required amount. To make the streak looks smoother use eraser to gently erase the sharp edges remaining or you may do some feathering
(Select>Feather [value may range between 20 to 100 according to image resolution]>Reverse Selection [Cmd (or CTRL in
PC)+Shift+I]>Backspace>Backspace).

3- From Filter>distort use Shear filter. Shear filter enables you to put anchor point in the middle to concave the image (you may need to rotate the layer 90 degrees before you use this filter properly). Do the required concave distortion.

4- If you want to increase transparency, from transparency panel dilute the layer such that it well fit with the background.

5- If you want to emphasize the streak you may duplicate the streak’s layer by dragging the layer in layer panel on the new layer icon, such that you decrease the transparency that resulted from stretching the layer in step (2).

5- If you are still not happy with the streak smoothness, do some Gaussian blur until you get the best result.

Hope this helps!

Mohamed Al-Dabbagh
Senior Graphic Designer
S
Sean
Dec 16, 2003
Hi Mohamed,

Thanks for the idea of the shear filter. That is yet another filter I have never used (I am a photographer) and presents me with yet another way of achieving my goal.

enjoy your day,

Sean

"In the End, we will remember not the words of our enemies, but the silence of our friends."

– Martin Luther King Jr. (1929-1968)

Redesigned – Last Updated 15 October 2003
Photo Archive @ http://www.tearnet.com/Sean

How to Improve Photoshop Performance

Learn how to optimize Photoshop for maximum speed, troubleshoot common issues, and keep your projects organized so that you can work faster than ever before!

Related Discussion Topics

Nice and short text about related topics in discussion sections