View Full Version : depth map blur

06-25-2003, 01:16 PM
hey all

i think this is the correct forum but if not could a mod please move it to the appropiate place.

can anyone tell me how i can blur an image based on a depth map. eg in photoshop how can i tell the gaussian blur filter to blur black pixels 100% and white pixels 0% or vice versa. also i do not want to apply the blur to the depth map layer but another layer. obviously i could isolate objects and place them on a seperate layer and blur that layer but this would not yield the desired effect.

i'm sure people must have wanted to do this before and it appears to be a simple operation, if anyone can help me out i'd be very grateful....

thanks yall..............kane..

06-25-2003, 08:19 PM
as far as i understand your question u could take the basic picture as background layer and then put a blured version of the pic on top of that after that use the depth pass as alpha channel for the blured pic.

Hope it helps


06-26-2003, 01:40 AM
What program you using?
To do depth blur you have to first make a gradient map from the original image. Take your picture and use blank and white to demonstrate which parts you want blurred. So for instance use the white to represent no blur and black to represent allot of blur. Gray in between. Then take it into a composting package like shake and put them together using z-blur.

Ian Jones
06-26-2003, 03:03 AM
In after FX I would use 'compound blur'. You select your z-depth pic and the levels determine the amount of blur in specific areas. I am unsure about exactly what 'compound blur' is though (in comparison to gaussian for example), I use it because it appears to work just perfectly for what I need.

06-26-2003, 03:55 AM
In Photoshop, copy the Depth map to a new channel, load the channel selection, and apply a little feather to it, then go back to the layer you want to blur, and apply your Gaussian blur to it. You may need to invert your Depth pass...to get the DOF effect to point in the right direction for your scene.

Feel free to tweak the levels of your Depth Map if you want to exploit it a bit more. I usually copy the Depth Map several times into new channels and tweak the levels to get a nice gradation for when I am blurring to simulate DOF effects in Photoshop.

Hope that helps.

06-26-2003, 07:44 AM
hey ppl

thanks for the responce..i use photoshop, i dont have access to any specific comp soft like ae or shake, but z-blur sounds exactly what i'm after....

policarpo..this is a nice option, i have tried this before but didn't get the results i wanted, but i'm sure by adjusting the levels and using several layers you can achieve a cool effect, though for animantion it's a bit hectic..

EvilE..duplicate the layer, blur and use depth map as alpha..brilliant why didn't i think of that....

i've just finished a scene with rendered dof, but the rendertimes (however nice the dof simulation is) have really put me off using it again.. i will do some tests with both suggestions and work out how i'm going to do it in the future......

thanks for your help....word oUt..

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