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Thread: Invisible Backgrounds

  1. #1
    Join Date
    Oct 2004
    Location
    UK - Milton Keynes
    Posts
    807

    Question Invisible Backgrounds

    Got some static images (jpeg + tiff) that I need to float over a video clip, playing in the background?

    I can do the transparent white or black (depending upon the static image background) but it also takes out some of the objects' white and black (obviously!)

    Though I could do it using an alpha channel - but I cant seem to?..

    Any chance of a step by step guide on how to take an object in an image (jpeg or tiff or psd) and make the background (whatever colour) transparent - without affecting the object? It?s late, and I think I'm missing something somewhere?. (probably brain cells?.)

    Thanks

    S

  2. #2
    can you send me your image, or post it here.
    So I can check it?

    only tiff's get transparency correct, but in photoshop - when you save - there are 3 different settings dialogs that have 'transparent' settings, its a bit confusing.

  3. #3
    i just changed the attachment file size limits and added the 'tiff' extension

  4. #4
    Looks like there are a couple of issues here,

    The main one seems to be photoshop files import with pre-multiplied alpha - which means they look a little wierd.
    But tiff files dont which means they composite OK in catalyst.

    I have created and tested a few files.

    1. Transparent text in photoshop - you have to remove any pixels in the background layer.
    2. Transparent text in photoshop saved as a tiff with the setting in the last attachment
    3. A blob or brush painting saved as a photoshop file
    4. A blob saved as a tiff
    5. text photoshop composite in pixelmad shows fringing meaning its pre-multiplied - not quite right
    6. text tif composite doesnt show fringing
    7. blob photoshop comp shows fringing
    8 blob/tif comp doesnt.
    9. tiff settings i used, showing transparency setting.
    Attached Images Attached Images
    Attached Files Attached Files

  5. #5
    Quote Originally Posted by Mr_P
    (jpeg + tiff)
    S
    I dont know anyway of making a transparent jpeg - but i could be wrong.
    Maybe jpeg 2000? but the performance of jpeg 2000 used to be terrible in quicktime

    http://www.jpeg.org/

    http://www.jpeg.org/jpeg2000/index.html

  6. #6
    To take a pre-existing object or photograph which has a background you want to remove -use the extract filter in photoshop.

    The extract filter takes quite a bit of experimentation.
    You are going to have to read the manual on how to use this

    But i took this image of some flowers and made the blue sky transparent.
    You have to hand draw around the edges to help the filter, the 'smart hilighting' check box helps enormously. i used a big brush size to outline the edges. your brush size will depend on the resolution of the images.

    the nicest thing about extract is that you dont have to be too accurate! just broad brush strokes, in close to the right place.
    Attached Files Attached Files

  7. #7
    Join Date
    Oct 2004
    Location
    UK - Milton Keynes
    Posts
    807

    it works

    Richard -

    thanks for the info - I've got it working now...

    I created a blank document in photoshop with a transparent background.
    Then used the magic mask tool to select the white areas in my graphic, then inverted the mask to select my object and copied it in to my new transparent document.
    Saved it as a tiff, with the settings suggested - and it works brilliantly, with no need for transparent colour effects. - Object floats over background with no noticeable distortion

    One of the issues I had was that I was using coreldraw (PC) to create the tiffs - and it doesn't save transparent backgrounds, although tiff format supports them... Basically it was merging the transparent with white... hence no transparency seen.

    Got a bit of work to do converting all the relevant tiffs - will try your second method mentioned.

    However, I can still use transparent white or tint colour effects for making simple text graphics on white backgrounds transparent

    Thanks for the help

    S

  8. #8
    If you have a lot of images a mac program like graphic convertor will batch convert an entire folder - if setup correctly.

    ( there may be other programs that do this... )

    http://versiontracker.com/dyn/moreinfo/macosx/11559

  9. #9
    Quote Originally Posted by Mr_P
    Then used the magic mask tool to select the white areas in my graphic, then inverted the mask to select my object and copied it in to my new transparent document.

    S
    when you have a complex image to separate with complex edges and ambiguous boundaries, using the extract filter is much better than using the magic mask.

  10. #10
    Join Date
    Mar 2004
    Location
    Stockholm
    Posts
    54
    Quote Originally Posted by samsc
    when you have a complex image to separate with complex edges and ambiguous boundaries, using the extract filter is much better than using the magic mask.
    There are several nice apps if you spend some money to give you very good result when extracting or masking you pictures.Timesavers!

    Extensis Mask Pro is cool:
    http://www.extensis.com/en/products/...=en_US&id=1018
    Peppe Tannemyr
    Beacon DigiGobos®
    www.digigobos.com / www.gobogroup.com

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