I heard that a lot of people blur the background in photoshop. I tried to do it on a studio shot with a grey background. I did it on a new layer, select around the model, invers and used gaussian blur, than adjust the opacity. I dont know if I'm wright but on the result in a big print I could see the separation between the blur and the non blur part of the background. Can somebody help me and I would be interested to see before and after results.
Martin,
If you have CS, it's better to use "Lens Blur" rather than Gaussian blur. If you feather correctly, and adjust the opacity once blurred - if too much, you will practically see no halo. One thing, though, if you have some area around the model, and close to it, especially around the feet for full length shots, you have to make the blur realistic by varying the depth of field of the blur. I hope you know what I mean. In other words, close objects should be in focus, and as you go more in the background photo, the blur becomes more pronounced.
richardj7, do you feather wright on the model or you leave a space between the model and the selection. Do you know what I mean? I dont know the lens blur but I'll try it for sure.
What I would do, and I find it to be much easier is to duplicate the layer, and do a complete lens blur on the whole image.
On the blurred image, I'd then use the eraser tool on the subject, and erase the blur part, to show the focused layer under. I use the soft edge eraser.
This also lets you adjust the opacity of the eraser, so you can make it more of a natural DOF effect.
I find it works very well, and more natural looking than outlining the subject.
I've done quite a bit of this in the past when I did not have an SLR with reasonable DOF. The methods above will help reduce the problem, but will not solve it. If you want to do a really, really good job, it takes a lot more time. Here is what needs to be done:
1) duplicate the Backgrouind Layer twice. Lable the top copy Subject, and the middle copy blurred.
2) on the top copy, do as good a job as you can to extract the subject from the background to be blurred. I either use the Extract filter or the magnetic lasso for this. SOmetimes I have just carefully used a mask to erase out all but the subject. This is essential, and the hardest part of the process. There is no getting around it. Once you've got this done, click the eyeball to make this layer invisible.
3) Next, you have to prepare the middle layer for blurring. One of the problems with the techniques outlined above is that if the subject gets included at all in the blur, it will show up. If not, you can almost always see the boundaries of the blur easily. In order to prepare this layer for bluring we have to (at least partially) remove the subject by cloning in around the edges. Depending upon the nature of the background, this can be either an easy task or more difficult. How much to clone in depends upon how much you will blur the bkg. Better to err on the side of overdoing it. The object here is to allow the blur of this layer to proceed as though there was no subject. If you try this you will see what I mean.
4) once the Blur layer is prepared, blur this using Lens Blur as suggested above (if you have CS or CS2), or use Gaussian Blur. The amount of blur depends on a number of issues, but if you want to be safe, duplicate the blur layer before you blur it and click the eyeball to make it invisible. If the amount of blur you used is not correct, you can always go back and redo it on the "saved" copy.
5) Now if your background actually shows the transition from near to far, you can add a mask layer to the Blur Layer, and, using the gradient tool, create a gradient mask to reduce the blur as the bacground approaches the intended in-focus DOF.
6) finally, reveal the subject layer. You will usually see some rough edges around the subject depending upon how careful you were with your extraction in step 2. These can be address by careful pixel editing, or sometimes by adding a mask layer and erasing with a low opacity eraser around the edges of the subject to ease the transition. Using a mask here instead of erasing the image itself, makes it easy to go back and rework areas.
I have an example that I did for someone else on this forum a while ago, but I'm hesitant to post another individual's work without permission. If you are interested I could email the original and the final copies to you.
Edward beat me to it but that is by far the best method. So many times I see blurred backgrounds that haven't taken into consideration dof for the blur. Blurred grass at the feet of the subject being a classic. As Edward says the most time consuming part is the extraction of the subject from the background,
but the extra time spent is well worth it. If you have a high contrast of foreground and background by far the fastest way of extracting the subject is to use channels.
Find the channel with the most separation of foreground subject from background and duplicate this channel, use the dodge and burn tools until you have a pure black and white channel, ctrl-click on channel and hey presto your subject is now selected to delete the background. This only works on sharp focus subjects...
Here's an exaple of one using channels technique, I used this to save having to painstaking draw around flowers in hair!...
I have a slighty different method using the lens blur in CS.
1. First duplicate your image layer, just so you have a back up.
2. Add a layer mask to the duplicate.
3. The aim is to recreate the different visual planes in the image on the layer mask, using the gradient tool where necessary to create a smooth transition an angled planes. Remember that you can alt+click the layer mask to see how your work is progressing.
4. Once you have this 'map' of the visual planes in the layer mask you can use it to guide photoshop's blurring with the lens blur filter by selecting 'layer mask' from the source menu at the top of the lens blur filter dialogue.
5. When your blur is done disable the layer mask to see the finished effect.
I used blurring on this image to exaggerate the depth of field and create a more dynamic look. Here is the layer mask I used for the above image (alt+click the layer mask to see this state)
You can see from the mask that the solid black areas will be in focus and the white blurred. All the grey areas inbetween are blurred less as photoshop uses your guide to determine the amount of blur to apply. Obviously, the better you are able to separate out the visual planes the better your blur will look.
I usually use this method to exaggerate blurring beyond what is realistic for effect, here are some others I've done using this technique:
The advantage of this method is that, with careful masking, you never see a halo from a part of the image that should be in focus because photoshop doesn't touch those parts of the image at all.
Edited by miles mute on Aug 17, 2005 at 09:57 PM GMT
No worries, I was in the same situation before I got a DSLR too, my G5 had a frustrating lack of blur so I went to all lengths to duplicate it and usually got carried away!
Can you expund a bit on using channels to separate out? thanks!
stevenbernard wrote:
Edward beat me to it but that is by far the best method.
SNIP
Find the channel with the most separation of foreground subject from background and duplicate this channel, use the dodge and burn tools until you have a pure black and white channel, ctrl-click on channel and hey presto your subject is now selected to delete the background. This only works on sharp focus subjects...
sorry Jamie I typed in a whole big explanantion then when I clicked on post I got a network error message and I really can't bring myself to type it all again sorry
stevenbernard wrote:
sorry Jamie I typed in a whole big explanantion then when I clicked on post I got a network error message and I really can't bring myself to type it all again sorry
saxmc wrote:
richardj7, do you feather wright on the model or you leave a space between the model and the selection. Do you know what I mean? I dont know the lens blur but I'll try it for sure.
Martin
Your method usually works quite well and is very quick for a solid background, just feather your selections before making a new layer from the selection.
You can then erase any of the feathered blur that touches the model.
If you have a detailed background you usually have to use the more elaborate, time consuming methods listed.
