Photography / Masking Tip replacing backgrounds

Started May 12, 2010 | Discussions thread
aka_den Regular Member • Posts: 237
Thanks Mike... I was able to use your images and...

...Picture Window Pro 5 with the following workflow:
(1) download the OP's 'backgound_only' and 'pineapple-bkg' jpegs.

(2) click on the 'pineapple-bkg' image, open Composite-AbsoluteDifference, set Overlay = the 'background_only' image, click OK.

Creates an 'AbsoluteDifference' image where the background image areas are black with some isolated black in the main subject image areas.

(3) click on the resulting (2) image, open Mask Tool - BrightnessCurve, form, 'lower-left' Apply Add, OK a BrokenLine curve = [0,0], [10,100], [100,100].

Masks the backgound image areas surrounding the main subject with a slight outline edge gradient.

(4) click on the resulting (3) mask image, open the Mask Tool - BrightnessCurve; form and 'lower-left' Apply Add the default [0,0], [100,100] diagonal curve; and then form, 'lower-left' Apply Subtract, OK a BrokenLine curve [0,100], [50,100], [100,0].

Subtracts the black [0%] to 50% toned outline edge gradient from the mask.

(5) click on the resulting (4) mask image, open the Mask Tool - FloodFill; select large background areas [black] as needed to isolate the main subject [white with gray mix]; Invert; OK.

Eliminates the main subject non-white mask image areas inside its outline.

The resulting (5) mask image is sharp edged and will require further preferential feathering and/or blur when used to Composite-Blend the main subject with its new background...

The resulting (5) mask was feathered -2, then +1 and the new background has a 0 to 100% toned colored gradient with 3.5% guassian HSV-V noise, and a 'drop shadow' was added to the main subject...

I am going to have to try this with actual working images. I can see that (1) the background needs to remain static between the two shots; (2) the camera's auto settings need to be switched to manual, so that the background only shot has the same exposure, focus, and aperature as the first shot; (3) main subject shadowing into the background may need to be taken into account; and (4) a rock steady tripod...

...looking forward to some trials and again Mike... thanks!!!

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