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craigm53606442
Participant
August 5, 2017
Question

Selecting the differences between two photos

  • August 5, 2017
  • 5 replies
  • 4438 views

I have searched high and low and cannot find a solution to this problem.

I am using photoshop CC and have two images taken on a tripod. One image is a background and the other is the same with an object in it.

I am trying to select the object and extract it.

Any help is much apprecaited.

    This topic has been closed for replies.

    5 replies

    C
    craigm53606442Author
    Participant
    August 5, 2017

    They are as similar as possible considering the constraints.

    My challenge is that A most images are more complex than this piece of wood and B I need the process to be fast and consistent.

    Chuck Uebele
    Community Expert
    Chuck UebeleCommunity Expert
    Community Expert
    August 5, 2017

    If you're other subjects are roughly the same size, get a roll of colored paper, plain white is acually better for eliminating unwanted color cast, that you can place your subject on and make the selection process easier.

    C
    craigm53606442Author
    Participant
    August 5, 2017

    Unfortunetly that is not an option in this case.

    JJMack
    Community Expert
    JJMackCommunity Expert
    Community Expert
    August 5, 2017

    You are joking right!   A Phone in automatic camera mode will never produce two image with the exactly same exposures you can see the difference with you eyes and difference blending mode shows differences are all over the images,.

    JJMack
    C
    craigm53606442Author
    Participant
    August 5, 2017

    Here is an example of the photos:

    https://flic.kr/p/Xe8tDX

    https://flic.kr/p/Xe8tTV

    In this scenario, I would be trying to extract the wooden frame.

    Semaphoric
    Community Expert
    SemaphoricCommunity Expert
    Community Expert
    August 5, 2017

    I would use the Pen tool to make a path around the frame, and then make a selection from it.

        

    JJMack
    Community Expert
    JJMackCommunity Expert
    Community Expert
    August 5, 2017

    That would only be helpful if the two image backgrounds were exactly the same and the object borders have nothing that matches the background it is on. Same exposure no shadows or lighting changes. You could stack the images and auto-align the layers. The backgrounds should be aligned if there was no tripod camera movement.  You could set the blending mode to difference then select the magic wand set sample point like 3px x 3px tolerance low contiguous mode and select the black background. Save the selection to mask the object.

    JJMack
    C
    craigm53606442Author
    Participant
    August 5, 2017

    Everything is the same. Lighting, exposure, no camera movement, etc.

    The background is a room, not a solid color.

    I have tried setting the blending mode to difference, but have not been able to just select the object.

    JJMack
    Community Expert
    JJMackCommunity Expert
    Community Expert
    August 5, 2017

    Do any of the object borders match anything in the background room?  When you set the top layer to difference the room should turn 100% black.  The Magic wand in contiguous mode should  be able to select the room.  Inverting the selection select the object.

    JJMack
    Chuck Uebele
    Community Expert
    Chuck UebeleCommunity Expert
    Community Expert
    August 5, 2017

    You can try to use difference blend mode to help make a selection, but if the subject is close to the same color as the background, it might not help much.

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