Automatic background removing
Albertin
Registered Users Posts: 4 Beginner grinner
Please excuse my poor english, I am french. Here is my question:
I am shooting a person outside at f stop 2.8 and the background is blurred because out of focus. I take a second picture without the person and without changing the focus. I take a third picture without the person but with the background in focus. All this is done on a tripod without moving the camera between the shots. I then want to cut out the person from the blrred background and put it on the one which is in focus. There must be a way to do it automaticly. May be by using a blend mode such as difference or apply image with soustraction? Any suggestions would be welcome.
Thanks in advance
Albertin
I am shooting a person outside at f stop 2.8 and the background is blurred because out of focus. I take a second picture without the person and without changing the focus. I take a third picture without the person but with the background in focus. All this is done on a tripod without moving the camera between the shots. I then want to cut out the person from the blrred background and put it on the one which is in focus. There must be a way to do it automaticly. May be by using a blend mode such as difference or apply image with soustraction? Any suggestions would be welcome.
Thanks in advance
Albertin
0
Comments
Masks are your friend here...place the image with the person on top of the sharp background and then just mask out the background.
There is not enough light to use a higher f-stop. I thought of using masks, but I would like to find some automatic way to create the mask by using the difference betwen the sharp pixels and the blurred ones. It would avoid to spend a lot of time to mask for exemple hair on foliage.
Albertin
Masking really wouldn't be that hard (particularly if you have a graphics tablet)...just do a hard brush rough outline of the entire grassy area, then go smaller and smaller, outlining more and more detail. If you're good at using masks, this can be done in 5-15 minutes depending on how complex the photo is.
In theory, I know what you're saying...you want a way for Photoshop to say "these pixels from this photo (original) are the same as these pixels in this photo (blurry background only)" and remove just the pixels that are the same, revealing the sharp background. It's sounds like something that COULD happen, but I just don't know if it can. Maybe somebody else knows something I don't.
I agree I could do a mask. As I am not very fast, it would take about 30 minutes. But this is supposed to be done on a big serie I'll take in Africa next december.
The idea of an automatic way using calculation came from a technic I read here: http://www.graficaobscura.com/depth/index.html
May be there is a way to adapt it to my problem. I just don't get it.
Albertin
Thanks for the link. Looks interesting, though I don't exactly understand how to implement it in Photoshop. Have you tried it? It seems to address exactly the problem you are trying to solve.
I don't understand enough about Apply Image or Calculation in Psd
In the Multifocus Method for Controlling Depth of Field only the focus changes; the objects in the image don't move. In my case, the camera doesn't move, neither the focus, but the person (or the object) is removed in the second image. My intuition tells me there is a way like soustracting the blurred image from the one in focus to create a mask, but I don't know how to do it. To automate the procedure later on would be easy by creating an action.
Albertin