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B/w with vibrant colour in one area. How to?

  • 04-01-2010 6:07pm
    #1
    Jackobyte
    Registered Users, Registered Users 2 Posts: 6,321 ✭✭✭


    I have seen this in a few pictures and I really like the effect. It is used on colour pictures (i think?) and makes all the picture, except a selected spot, B&W, leaving one area with a vibrant colour.

    I believe it is done using Adobe Photoshop CS4, which I have access to, but I do not know how to do it. Any help?



    EDIT: I worked out how to do it by just playing around with it for a while.


Comments

  • #2
    CabanSail
    Moderators, Category Moderators, Arts Moderators, Entertainment Moderators Posts: 9,047 CMod ✭✭✭✭CabanSail


    It's called "Selective Colour" It is an effect which is sometimes used and more often abused.

    [Carl Sagan] Imagine the grains of sand on a beach .... well there are probably as many ways to do it as that. [/Carl Sagan]

    Probably an exageration (only a bit) but there are quite a few ways to do this. Probably best to have a layer for the Mono & another for the colour & that way you can adjust the properties of each seperately.


  • #3
    Jackobyte
    Registered Users, Registered Users 2 Posts: 6,321 ✭✭✭Jackobyte


    CabanSail wrote: »
    It's called "Selective Colour" It is an effect which is sometimes used and more often abused.

    [Carl Sagan] Imagine the grains of sand on a beach .... well there are probably as many ways to do it as that. [/Carl Sagan]

    Probably an exageration (only a bit) but there are quite a few ways to do this. Probably best to have a layer for the Mono & another for the colour & that way you can adjust the properties of each seperately.
    I found the easiest way to do it was to add a black and white layer and then using the eraser tool on this layer, erase the parts you wish to see the original colours. Thanks for your help.

    J.


  • #4
    Heebie
    Registered Users, Registered Users 2 Posts: 1,302 ✭✭✭Heebie


    This is similar to the method I'd use. (Photoshop only for this one.. GIMP doesn't have "adjustment layers" the way Photoshop does..making this difficult.)

    I would first edit the photo, in color, until I decide the color was as garish as I wanted in the color section of the image.

    Then.. add a "color mixer" layer, and choose to "mix to greyscale".. which allows you to "blend" the R,G and B to get the contrastiness that you want. (Think of R, G and B as being three separate black & white photos.. but one of them being red, one of them being green, and one blue. each of those "photos" was exposed ONLY to light of the corresponding colour.. and how they interact with each other is akin to using magenta & yellow filters in a darkroom.) The Red layer should look very similar contrast-wise to what the color image looks like. The green (the opposite of magenta - thus it's relationship to the magenta filter in the darkroom.) layer should be VERY contrasty, and the blue (which is the opposite of yellow, which is why it corresponds to a yellow filter) will be very low-contrast.
    By "mixing" the three, you have VERY fine control over the resulting black & white portion of the image.
    I start with a mix of 50% on red, 40% on green, and 10% on blue, then adjust them from there.. generally keeping the overall mix to a total of around 100%. (so.. the three numbers will always sum up to around 100)

    Once I'm satisfied that I have the color I want for the color section, and the black & white I want for the black & white section (in this case the REST of the image) I then add a transparency mask to the adjustment layer. (This is an "alpha" layer.. that gives you VERY fine control over the transparency of the image.. as it gives you 256 shades [in 8-bit colour mode.. more in 16-bit colour mode] of "blend" so you can get a nice smooth transition (or a very sharp one) between the colour & B&W sections of the image.

    Now.. when you're editing the mask.. "painting" in "normal mode" with black will make the layer transparent where you pain. (the lighter shade of grey you use.. the less affected it is.) I will generally use an airbrush tool, with about 80% flow, and some feathering. I'll use a large brush size to do the centre of the area that I want to "show through", and around it's edges I'll make the brush smaller to I can follow contours of things in the image more easily.

    When painting in a mask.. it's really a good idea to make sure that masking is shown in red. (this is the default.. but you can shut it off.. and it'll make it really difficult to see what you're doing.)

    One should definitely play with this.. as there's a lot of "personal taste" involved.



    Jackobyte wrote: »
    I found the easiest way to do it was to add a black and white layer and then using the eraser tool on this layer, erase the parts you wish to see the original colours. Thanks for your help.

    J.


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